The horse is a prey animal, the human a predator. Our shared trust and athleticism is a neurobiological miracle
Janet Jones – 14 January 2022
Horse-and-human teams perform complex manoeuvres in competitions of all sorts. Together, we can gallop up to obstacles standing 8 feet (2.4 metres) high, leave the ground, and fly blind – neither party able to see over the top until after the leap has been initiated. Adopting a flatter trajectory with greater speed, horse and human sail over broad jumps up to 27 feet (more than 8 metres) long. We run as one at speeds of 44 miles per hour (nearly 70 km/h), the fastest velocity any land mammal carrying a rider can achieve. In freestyle dressage events, we dance in place to the rhythm of music, trot sideways across the centre of an arena with huge leg-crossing steps, and canter in pirouettes with the horse’s front feet circling her hindquarters. Galloping again, the best horse-and-human teams can slide 65 feet (nearly 20 metres) to a halt while resting all their combined weight on the horse’s hind legs. Endurance races over extremely rugged terrain test horses and riders in journeys that traverse up to 500 miles (805 km) of high-risk adventure.
No one disputes the athleticism fuelling these triumphs, but few people comprehend the mutual cross-species interaction that is required to accomplish them. The average horse weighs 1,200 pounds (more than 540 kg), makes instantaneous movements, and can become hysterical in a heartbeat. Even the strongest human is unable to force a horse to do anything she doesn’t want to do. Nor do good riders allow the use of force in training our magnificent animals. Instead, we hold ourselves to the higher standard of motivating horses to cooperate freely with us in achieving the goals of elite sports as well as mundane chores. Under these conditions, the horse trained with kindness, expertise and encouragement is a willing, equal participant in the action.
That action is rooted in embodied perception and the brain. In mounted teams, horses, with prey brains, and humans, with predator brains, share largely invisible signals via mutual body language. These signals are received and transmitted through peripheral nerves leading to each party’s spinal cord. Upon arrival in each brain, they are interpreted, and a learned response is generated. It, too, is transmitted through the spinal cord and nerves. This collaborative neural action forms a feedback loop, allowing communication from brain to brain in real time. Such conversations allow horse and human to achieve their immediate goals in athletic performance and everyday life. In a very real sense, each species’ mind is extended beyond its own skin into the mind of another, with physical interaction becoming a kind of neural dance.
Horses in nature display certain behaviours that tempt observers to wonder whether competitive manoeuvres truly require mutual communication with human riders. For example, the feral horse occasionally hops over a stream to reach good food or scrambles up a slope of granite to escape predators. These manoeuvres might be thought the precursors to jumping or rugged trail riding. If so, we might imagine that the performance horse’s extreme athletic feats are innate, with the rider merely a passenger steering from above. If that were the case, little requirement would exist for real-time communication between horse and human brains.
In fact, though, the feral hop is nothing like the trained leap over a competition jump, usually commenced from short distances at high speed. Today’s Grand Prix jump course comprises about 15 obstacles set at sharp angles to each other, each more than 5 feet high and more than 6 feet wide (1.5 x 1.8 metres). The horse-and-human team must complete this course in 80 or 90 seconds, a time allowance that makes for acute turns, diagonal flight paths and high-speed exits. Comparing the wilderness hop with the show jump is like associating a flintstone with a nuclear bomb. Horses and riders undergo many years of daily training to achieve this level of performance, and their brains share neural impulses throughout each experience.
These examples originate in elite levels of horse sport, but the same sort of interaction occurs in pastures, arenas and on simple trails all over the world. Any horse-and-human team can develop deep bonds of mutual trust, and learn to communicate using body language, knowledge and empathy.
Like it or not, we are the horse’s evolutionary enemy, yet they behave toward us as if inclined to become a friend
The critical component of the horse in nature, and her ability to learn how to interact so precisely with a human rider, is not her physical athleticism but her brain. The first precise magnetic resonance image of a horse’s brain appeared only in 2019, allowing veterinary neurologists far greater insight into the anatomy underlying equine mental function. As this new information is disseminated to horse trainers and riders for practical application, we see the beginnings of a revolution in brain-based horsemanship. Not only will this revolution drive competition to higher summits of success, and animal welfare to more humane levels of understanding, it will also motivate scientists to research the unique compatibility between prey and predator brains. Nowhere else in nature do we see such intense and intimate collaboration between two such disparate minds.
Three natural features of the equine brain are especially important when it comes to mind-melding with humans. First, the horse’s brain provides astounding touch detection. Receptor cells in the horse’s skin and muscles transduce – or convert – external pressure, temperature and body position to neural impulses that the horse’s brain can understand. They accomplish this with exquisite sensitivity: the average horse can detect less pressure against her skin than even a human fingertip can.
Second, horses in nature use body language as a primary medium of daily communication with each other. An alpha mare has only to flick an ear toward a subordinate to get him to move away from her food. A younger subordinate, untutored in the ear flick, receives stronger body language – two flattened ears and a bite that draws blood. The notion of animals in nature as kind, gentle creatures who never hurt each other is a myth.
Third, by nature, the equine brain is a learning machine. Untrammelled by the social and cognitive baggage that human brains carry, horses learn in a rapid, pure form that allows them to be taught the meanings of various human cues that shape equine behaviour in the moment. Taken together, the horse’s exceptional touch sensitivity, natural reliance on body language, and purity of learning form the tripod of support for brain-to-brain communication that is so critical in extreme performance.
One of the reasons for budding scientific fascination with neural horse-and-human communication is the horse’s status as a prey animal. Their brains and bodies evolved to survive completely different pressures than our human physiologies. For example, horse eyes are set on either side of their head for a panoramic view of the world, and their horizontal pupils allow clear sight along the horizon but fuzzy vision above and below. Their eyes rotate to maintain clarity along the horizon when their heads lie sideways to reach grass in odd locations. Equine brains are also hardwired to stream commands directly from the perception of environmental danger to the motor cortex where instant evasion is carried out. All of these features evolved to allow the horse to survive predators.
Conversely, human brains evolved in part for the purpose of predation – hunting, chasing, planning… yes, even killing – with front-facing eyes, superb depth perception, and a prefrontal cortex for strategy and reason. Like it or not, we are the horse’s evolutionary enemy, yet they behave toward us as if inclined to become a friend.
The fact that horses and humans can communicate neurally without the external mediation of language or equipment is critical to our ability to initiate the cellular dance between brains. Saddles and bridles are used for comfort and safety, but bareback and bridleless competitions prove they aren’t necessary for highly trained brain-to-brain communication. Scientific efforts to communicate with predators such as dogs and apes have often been hobbled by the use of artificial media including human speech, sign language or symbolic lexigram. By contrast, horses allow us to apply a medium of communication that is completely natural to their lives in the wild and in captivity.
The horse’s prey brain is designed to notice and evade predators. How ironic, and how riveting, then, that this prey brain is the only one today that shares neural communication with a predator brain. It offers humanity a rare view into a prey animal’s world, almost as if we were wolves riding elk or coyotes mind-melding with cottontail bunnies.
Highly trained horses and riders send and receive neural signals using subtle body language. For example, a rider can apply invisible pressure with her left inner calf muscle to move the horse laterally to the right. That pressure is felt on the horse’s side, in his skin and muscle, via proprioceptive receptor cells that detect body position and movement. Then the signal is transduced from mechanical pressure to electrochemical impulse, and conducted up peripheral nerves to the horse’s spinal cord. Finally, it reaches the somatosensory cortex, the region of the brain responsible for interpreting sensory information.
Riders can sometimes guess that an invisible object exists by detecting subtle equine reactions
This interpretation is dependent on the horse’s knowledge that a particular body signal – for example, inward pressure from a rider’s left calf – is associated with a specific equine behaviour. Horse trainers spend years teaching their mounts these associations. In the present example, the horse has learned that this particular amount of pressure, at this speed and location, under these circumstances, means ‘move sideways to the right’. If the horse is properly trained, his motor cortex causes exactly that movement to occur.
By means of our human motion and position sensors, the rider’s brain now senses that the horse has changed his path rightward. Depending on the manoeuvre our rider plans to complete, she will then execute invisible cues to extend or collect the horse’s stride as he approaches a jump that is now centred in his vision, plant his right hind leg and spin in a tight fast circle, push hard off his hindquarters to chase a cow, or any number of other movements. These cues are combined to form that mutual neural dance, occurring in real time, and dependent on natural body language alone.
The example of a horse moving a few steps rightward off the rider’s left leg is extremely simplistic. When you imagine a horse and rider clearing a puissance wall of 7.5 feet (2.4 metres), think of the countless receptor cells transmitting bodily cues between both brains during approach, flight and exit. That is mutual brain-to-brain communication. Horse and human converse via body language to such an extreme degree that they are able to accomplish amazing acts of understanding and athleticism. Each of their minds has extended into the other’s, sending and receiving signals as if one united brain were controlling both bodies.
Analysis of brain-to-brain communication between horses and humans elicits several new ideas worthy of scientific notice. Because our minds interact so well using neural networks, horses and humans might learn to borrow neural signals from the party whose brain offers the highest function. For example, horses have a 340-degree range of view when holding their heads still, compared with a paltry 90-degree range in humans. Therefore, horses can see many objects that are invisible to their riders. Yet riders can sometimes guess that an invisible object exists by detecting subtle equine reactions.
Specifically, neural signals from the horse’s eyes carry the shape of an object to his brain. Those signals are transferred to the rider’s brain by a well-established route: equine receptor cells in the retina lead to equine detector cells in the visual cortex, which elicits an equine motor reaction that is then sensed by the rider’s human body. From there, the horse’s neural signals are transmitted up the rider’s spinal cord to the rider’s brain, and a perceptual communication loop is born. The rider’s brain can now respond neurally to something it is incapable of seeing, by borrowing the horse’s superior range of vision.
These brain-to-brain transfers are mutual, so the learning equine brain should also be able to borrow the rider’s vision, with its superior depth perception and focal acuity. This kind of neural interaction results in a horse-and-human team that can sense far more together than either party can detect alone. In effect, they share effort by assigning labour to the party whose skills are superior at a given task.
There is another type of skillset that requires a particularly nuanced cellular dance: sharing attention and focus. Equine vigilance allowed horses to survive 56 million years of evolution – they had to notice slight movements in tall grasses or risk becoming some predator’s dinner. Consequently, today it’s difficult to slip even a tiny change past a horse, especially a young or inexperienced animal who has not yet been taught to ignore certain sights, sounds and smells.
By contrast, humans are much better at concentration than vigilance. The predator brain does not need to notice and react instantly to every stimulus in the environment. In fact, it would be hampered by prey vigilance. While reading this essay, your brain sorts away the sound of traffic past your window, the touch of clothing against your skin, the sight of the masthead that says ‘Aeon’ at the top of this page. Ignoring these distractions allows you to focus on the content of this essay.
Horses and humans frequently share their respective attentional capacities during a performance. A puissance horse galloping toward an enormous wall cannot waste vigilance by noticing the faces of each person in the audience. Likewise, the rider cannot afford to miss a loose dog that runs into the arena outside her narrow range of vision and focus. Each party helps the other through their primary strengths.
Such sharing becomes automatic with practice. With innumerable neural contacts over time, the human brain learns to heed signals sent by the equine brain that say, in effect: ‘Hey, what’s that over there?’ Likewise, the equine brain learns to sense human neural signals that counter: ‘Let’s focus on this gigantic wall right here.’ Each party sends these messages by body language and receives them by body awareness through two spinal cords, then interprets them inside two brains, millisecond by millisecond.
The rider’s physical cues are transmitted by neural activation from the horse’s surface receptors to the horse’s brain
Finally, it is conceivable that horse and rider can learn to share features of executive function – the human brain’s ability to set goals, plan steps to achieve them, assess alternatives, make decisions and evaluate outcomes. Executive function occurs in the prefrontal cortex, an area that does not exist in the equine brain. Horses are excellent at learning, remembering and communicating – but they do not assess, decide, evaluate or judge as humans do.
Shying is a prominent equine behaviour that might be mediated by human executive function in well-trained mounts. When a horse of average size shies away from an unexpected stimulus, riders are sitting on top of 1,200 pounds of muscle that suddenly leaps sideways off all four feet and lands five yards away. It’s a frightening experience, and often results in falls that lead to injury or even death. The horse’s brain causes this reaction automatically by direct connection between his sensory and motor cortices.
Though this possibility must still be studied by rigorous science, brain-to-brain communication suggests that horses might learn to borrow small glimmers of executive function through neural interaction with the human’s prefrontal cortex. Suppose that a horse shies from an umbrella that suddenly opens. By breathing steadily, relaxing her muscles, and flexing her body in rhythm with the horse’s gait, the rider calms the animal using body language. Her physical cues are transmitted by neural activation from his surface receptors to his brain. He responds with body language in which his muscles relax, his head lowers, and his frightened eyes return to their normal size. The rider feels these changes with her body, which transmits the horse’s neural signals to the rider’s brain.
From this point, it’s only a very short step – but an important one – to the transmission and reception of neural signals between the rider’s prefrontal cortex (which evaluates the unexpected umbrella) and the horse’s brain (which instigates the leap away from that umbrella). In practice, to reduce shying, horse trainers teach their young charges to slow their reactions and seek human guidance.
Brain-to-brain communication between horses and riders is an intricate neural dance. These two species, one prey and one predator, are living temporarily in each other’s brains, sharing neural information back and forth in real time without linguistic or mechanical mediation. It is a partnership like no other. Together, a horse-and-human team experiences a richer perceptual and attentional understanding of the world than either member can achieve alone. And, ironically, this extended interspecies mind operates well not because the two brains are similar to each other, but because they are so different.
Janet Jones applies brain research to training horses and riders. She has a PhD from the University of California, Los Angeles, and for 23 years taught the neuroscience of perception, language, memory, and thought. She trained horses at a large stable early in her career, and later ran a successful horse-training business of her own. Her most recent book, Horse Brain, Human Brain (2020), is currently being translated into seven languages.
Edited by Pam Weintraub
Aug. 25, 2008
Crows and their relatives among them ravens, magpies and jays are renowned for their intelligence and for their ability to flourish in human-dominated landscapes. That ability may have to do with cross-species social skills. In the Seattle area, where rapid suburban growth has attracted a thriving crow population, researchers have found that the birds can recognize individual human faces.
John M. Marzluff, a wildlife biologist at the University of Washington, has studied crows and ravens for more than 20 years and has long wondered if the birds could identify individual researchers. Previously trapped birds seemed more wary of particular scientists, and often were harder to catch. “I thought, ‘Well, it’s an annoyance, but it’s not really hampering our work,’ ” Dr. Marzluff said. “But then I thought we should test it directly.”
To test the birds’ recognition of faces separately from that of clothing, gait and other individual human characteristics, Dr. Marzluff and two students wore rubber masks. He designated a caveman mask as “dangerous” and, in a deliberate gesture of civic generosity, a Dick Cheney mask as “neutral.” Researchers in the dangerous mask then trapped and banded seven crows on the university’s campus in Seattle.
In the months that followed, the researchers and volunteers donned the masks on campus, this time walking prescribed routes and not bothering crows.
The crows had not forgotten. They scolded people in the dangerous mask significantly more than they did before they were trapped, even when the mask was disguised with a hat or worn upside down. The neutral mask provoked little reaction. The effect has not only persisted, but also multiplied over the past two years. Wearing the dangerous mask on one recent walk through campus, Dr. Marzluff said, he was scolded by 47 of the 53 crows he encountered, many more than had experienced or witnessed the initial trapping. The researchers hypothesize that crows learn to recognize threatening humans from both parents and others in their flock.
After their experiments on campus, Dr. Marzluff and his students tested the effect with more realistic masks. Using a half-dozen students as models, they enlisted a professional mask maker, then wore the new masks while trapping crows at several sites in and around Seattle. The researchers then gave a mix of neutral and dangerous masks to volunteer observers who, unaware of the masks’ histories, wore them at the trapping sites and recorded the crows’ responses.
The reaction to one of the dangerous masks was “quite spectacular,” said one volunteer, Bill Pochmerski, a retired telephone company manager who lives near Snohomish, Wash. “The birds were really raucous, screaming persistently,” he said, “and it was clear they weren’t upset about something in general. They were upset with me.”
Again, crows were significantly more likely to scold observers who wore a dangerous mask, and when confronted simultaneously by observers in dangerous and neutral masks, the birds almost unerringly chose to persecute the dangerous face. In downtown Seattle, where most passersby ignore crows, angry birds nearly touched their human foes. In rural areas, where crows are more likely to be viewed as noisy “flying rats” and shot, the birds expressed their displeasure from a distance.
Though Dr. Marzluff’s is the first formal study of human face recognition in wild birds, his preliminary findings confirm the suspicions of many other researchers who have observed similar abilities in crows, ravens, gulls and other species. The pioneering animal behaviorist Konrad Lorenz was so convinced of the perceptive capacities of crows and their relatives that he wore a devil costume when handling jackdaws. Stacia Backensto, a master’s student at the University of Alaska Fairbanks who studies ravens in the oil fields on Alaska’s North Slope, has assembled an elaborate costume including a fake beard and a potbelly made of pillows because she believes her face and body are familiar to previously captured birds.
Kevin J. McGowan, an ornithologist at the Cornell Laboratory of Ornithology who has trapped and banded crows in upstate New York for 20 years, said he was regularly followed by birds who have benefited from his handouts of peanuts and harassed by others he has trapped in the past.
Why crows and similar species are so closely attuned to humans is a matter of debate. Bernd Heinrich, a professor emeritus at the University of Vermont known for his books on raven behavior, suggested that crows’ apparent ability to distinguish among human faces is a “byproduct of their acuity,” an outgrowth of their unusually keen ability to recognize one another, even after many months of separation.
Dr. McGowan and Dr. Marzluff believe that this ability gives crows and their brethren an evolutionary edge. “If you can learn who to avoid and who to seek out, that’s a lot easier than continually getting hurt,” Dr. Marzluff said. “I think it allows these animals to survive with us and take advantage of us in a much safer, more effective way.”
Neuropsych — September 29, 2020
Crows have their own version of the human cerebral cortex.
Robby Berman Share Crows are self-aware just like us, says new study on Facebook Share Crows are self-aware just like us, says new study on Twitter Share Crows are self-aware just like us, says new study on LinkedIn Crows and the rest of the corvid family keep turning out to be smarter and smarter. New research observes them thinking about what they’ve just seen and associating it with an appropriate response. A corvid’s pallium is packed with more neurons than a great ape’s.
It’s no surprise that corvids — the “crow family” of birds that also includes ravens, jays, magpies, and nutcrackers — are smart. They use tools, recognize faces, leave gifts for people they like, and there’s even a video on Facebook showing a crow nudging a stubborn little hedgehog out of traffic. Corvids will also drop rocks into water to push floating food their way.
What is perhaps surprising is what the authors of a new study published last week in the journal Science have found: Crows are capable of thinking about their own thoughts as they work out problems. This is a level of self-awareness previously believed to signify the kind of higher intelligence that only humans and possibly a few other mammals possess. A crow knows what a crow knows, and if this brings the word sentience to your mind, you may be right.
It’s long been assumed that higher intellectual functioning is strictly the product of a layered cerebral cortex. But bird brains are different. The authors of the study found crows’ unlayered but neuron-dense pallium may play a similar role for the avians. Supporting this possibility, another study published last week in Science finds that the neuroanatomy of pigeons and barn owls may also support higher intelligence.
“It has been a good week for bird brains!” crow expert John Marzluff of the University of Washington tells Stat. (He was not involved in either study.)
Corvids are known to be as mentally capable as monkeys and great apes. However, bird neurons are so much smaller that their palliums actually contain more of them than would be found in an equivalent-sized primate cortex. This may constitute a clue regarding their expansive mental capabilities.
In any event, there appears to be a general correspondence between the number of neurons an animal has in its pallium and its intelligence, says Suzana Herculano-Houzel in her commentary on both new studies for Science. Humans, she says, sit “satisfyingly” atop this comparative chart, having even more neurons there than elephants, despite our much smaller body size. It’s estimated that crow brains have about 1.5 billion neurons.
The kind of higher intelligence crows exhibited in the new research is similar to the way we solve problems. We catalog relevant knowledge and then explore different combinations of what we know to arrive at an action or solution.
The researchers, led by neurobiologist Andreas Nieder of the University of Tübingen in Germany, trained two carrion crows (Corvus corone), Ozzie and Glenn.
The crows were trained to watch for a flash — which didn’t always appear — and then peck at a red or blue target to register whether or not a flash of light was seen. Ozzie and Glenn were also taught to understand a changing “rule key” that specified whether red or blue signified the presence of a flash with the other color signifying that no flash occurred.
In each round of a test, after a flash did or didn’t appear, the crows were presented a rule key describing the current meaning of the red and blue targets, after which they pecked their response.
This sequence prevented the crows from simply rehearsing their response on auto-pilot, so to speak. In each test, they had to take the entire process from the top, seeing a flash or no flash, and then figuring out which target to peck.
As all this occurred, the researchers monitored their neuronal activity. When Ozzie or Glenn saw a flash, sensory neurons fired and then stopped as the bird worked out which target to peck. When there was no flash, no firing of the sensory neurons was observed before the crow paused to figure out the correct target.
Nieder’s interpretation of this sequence is that Ozzie or Glenn had to see or not see a flash, deliberately note that there had or hadn’t been a flash — exhibiting self-awareness of what had just been experienced — and then, in a few moments, connect that recollection to their knowledge of the current rule key before pecking the correct target.
During those few moments after the sensory neuron activity had died down, Nieder reported activity among a large population of neurons as the crows put the pieces together preparing to report what they’d seen. Among the busy areas in the crows’ brains during this phase of the sequence was, not surprisingly, the pallium.
Overall, the study may eliminate the layered cerebral cortex as a requirement for higher intelligence. As we learn more about the intelligence of crows, we can at least say with some certainty that it would be wise to avoid angering one.
Leão Serva, 2 de julho de 2021
Primatologista Frans De Waal fala sobre a inteligência e as emoções dos macacos
O encontro entre a chimpanzé idosa, dias antes de morrer, e seu amigo da vida toda, cientista também idoso, é uma cena inesquecível: a alegria irradiante de Mama, 59, ao abraçar o primatologista Jan Van Hooff, já octogenário, é um gesto reconhecível por milhões de espectadores do Youtube, em todos os cantos do planeta.
O ensaísta Frans de Waal, autor de best-sellers como “A Era da Empatia” e outros estudos sobre comportamentos e emoções dos macacos, usou a cena como mote e título de seu novo livro, “O Último Abraço da Matriarca” (Zahar, 452 págs.).
De Waal foi aluno de Van Hoof e conhecia muito bem Mama, a quem ele estudou e acompanhou por meio século de estudos do comportamento animal.
Como em seus outros livros, o conteúdo é um permanente diálogo entre o comportamento animal e o dos homens. Os chimpanzés e bonobos, que ele define como nossos “parentes” mais próximos, são usados para entender comportamentos humanos e destacar aquelas características que perdemos ou esquecemos ao longo do processo evolutivo.
Algumas delas, qualidades essenciais, atualíssimas, como a tolerância com os indivíduos que tem comportamentos diferentes.
Nesta entrevista, ele antecipa que seu novo livro terá como tema a questão de gêneros nas sociedades de primatas. E antecipa uma conclusão: “Creio que nós humanos podemos aprender muito sobre tolerância com eles”.
A revista “National Geographic” recentemente publicou uma capa sobre os chimpanzés cujo título era: ‘Sapiens?’, com uma interrogação. O senhor crê que os grandes primatas são sapiens?
Eles são muito inteligentes e nós, humanos, nos orgulhamos de nossa inteligência também. Mas quanto mais estudamos e aprendemos sobre os chimpanzés ao longo dos últimos 25 anos, mais encontramos manifestações do mesmo tipo de inteligência. Por exemplo, os chimpanzés são capazes de pensar adiante, podem pensar no futuro, podem planejar o futuro. Também pensam no passado, se lembram de eventos específicos do passado. Eles testar coisas, criar ferramentas e podem se reconhecer no espelho. Então, existem muitos sinais de que eles têm alto nível de inteligência, que os diferencia dos outros animais.
Em seus livros, o senhor descreve vários rituais e formas de mediação de conflitos entre chimpanzés, como fazer cafuné após uma briga. Quais são as formas similares com que os humanos fazem isso?
Por exemplo, depois de uma briga, eles se beijam e se abraçam. Normalmente, depois de 10 minutos eles se aproximam e têm algum contato e depois disso eles fazem carinhos como cafunés. Nós humanos normalmente somos menos físicos: pedimos desculpas, dizemos alguma coisa ou fazemos algo gentil, como trazer um café, como forma de reconciliação. Mas é claro que se for em uma família, pode ter também uma dimensão física, pode ser até sexual, como acontece em certas espécies de primatas. E abraçar e beijar são comportamentos muito humanos e os humanos também fazem isso.
Então, qual é a principal diferença entre os humanos e os outros primatas?
Há muitas semelhanças entre os pontos básicos de nossa inteligência humana e a desses animais. Há uma área em que temos uma diferença, que é a linguagem. É claro que os macacos se comunicam, como outros animais também, eles têm sinais que fazem uns para os outros. Mas, a comunicação simbólica, que pode se desenvolver, mudar, variar, pois o homem tem tantas linguagens diferentes, essa é uma propriedade unicamente humana. E é uma capacidade muito importante, porque podemos nos comunicar com pessoas que estão à distância, como estávamos fazendo agora, sobre coisas que não estão nem aqui e nem aí, isso é algo impossível para outros animais.
Pensando no caso da gorila Koko, que tinha domínio da língua de sinais e com ela se comunicava com humanos, o senhor diria que ela tinha um domínio humano da linguagem?
Não, eu não diria isso. Veja, existem hoje muitos macacos treinados para compreender as línguas de sinais e gestos com as mãos, inclusive comunicação simbólica. Mas os resultados são realmente desapontadores. Eles podem fazer algumas coisas, podem aprender uma centena de símbolos, mas a comunicação com eles continua sendo muito limitada. É mais limitada do que aquela que você pode ter com uma criança de dois anos, aproximadamente. Então, os experimentos de linguagem com macacos já não são muito populares, porque não apresentaram bons resultados.
Suponha que um casal humano tenha um filho e no mesmo momento adote um bebê chimpanzé e decida criar os dois juntos como filhos e irmãos. Até quando o desenvolvimento deles será idêntico?
Essa é uma pergunta interessante, porque pessoas já tentaram isso. Houve famílias nas décadas de 1950 e 1960 que tentaram criar seus filhos na companhia de bebês chimpanzés. O curioso é que esses projetos foram interrompidos porque as crianças humanas começaram a imitar os macacos, ao invés do contrário. As crianças começaram a se comportar como chimpanzés, pulando pra cima e pra baixo e grunhindo como macacos, por isso o programa foi interrompido. Mas os filhotes de macacos, se criados em uma família de humanos, eles fazem muitas das mesmas coisas: eles vêm televisão, gostam de jogar jogos. Algumas vezes eles se comportam fora das regras humanas, escalam as cortinas, sobem no telhado, coisa que as pessoas não gostam nada. Mas, em geral, quando são novos, eles se comportaram como crianças e brincam como crianças.
É correto dizer que só os humanos matam por razões como vingança, ódio, rancor, ambição, inveja e outras razões que não estão ligadas à alimentação ou ao instinto de sobrevivência?
Eu creio que isso seja verdade, porque chimpanzés são animais muito agressivos e eles podem algumas vezes matar uns aos outros por poder, por exemplo, disputa de comando sobre o grupo ou por território, quando eles defendem seus territórios contra outros. Nós temos um outro parente próximo, o bonobo. Eles são tão próximos de nós quanto os chimpanzés. Eles são muito mais amigáveis, não são tão agressivos. Mas há espécies de primatas que matam por outras questões que não só por alimento, sobrevivência ou coisas como essas.
Eu entendo que os chimpanzés tendem a resolver seus conflitos brigando, enquanto os bonobos têm uma diplomacia mais relacionada à sexualidade e à afetividade. O senhor diria que os homens têm um lado chimpanzé mais desenvolvido ou temos características desses dois parentes, dessas duas tendências?
Nós temos os dois lados: nós podemos ser eróticos e sexuais como os bonobos mas também podemos nos tornar violentos como os chimpanzés. Entre os chimpanzés, os homens são os dominantes enquanto os bonobos são dominados pelas mulheres. Por isso algumas pessoas dizem que somos mais parecidos com os chimpanzés. Eu não tenho essa certeza, eu acredito que temos muito da empatia e da sexualidade dos bonobos. Então, eu creio que somos uma mistura das duas espécies. Além disso, nós temos nossa própria evolução, a evolução humana, que se desenvolve há muito tempo. Nós desenvolvemos coisas novas, como a linguagem e o modelo de famílias, formadas por Pai, Mãe e crianças. Isso não vemos em nenhum outro macaco.
Em seus livros o senhor mostra que os macacos são capazes de entender a linguagem corporal dos outros, muito mais do que nós humanos conseguimos. O senhor acredita que o predomínio da linguagem verbal deteriorou nossa capacidade de entender as expressões do corpo?
É uma questão interessante: nós humanos confiamos tanto na linguagem verbal, prestamos tanta atenção ao que uma pessoa diz que muitas vezes esquecemos o quanto somos sensíveis a questões como a expressão facial, o tom de voz, o corpo. Nós somos de fato muito bons na leitura da linguagem corporal mas muitas vezes esquecemos isso. Por exemplo: quando eu vejo debates entre políticos na TV, frequentemente tiro o som, não quero ouvir o que eles dizem porque eles estão sempre mentindo, quero apenas ver sua linguagem corporal, que ela é muito mais informativa do que a linguagem verbal.
E ao observá-lo, o senhor diria que Donald Trump é um macho alfa, se comporta como um líder chimpanzé?
O problema com isso é que eu usei a expressão “macho alfa” para definir machos chimpanzés e muitos dos “machos alfa” que eu conheço são bons líderes: eles mantêm o grupo unido, eles unem as partes quando se dividem, garantem a preservação da ordem na sociedade, eles têm empatia pelos outros. Essas são qualidades que muitos líderes do mundo humano não têm. Nós os chamamos algumas vezes de “alfa” porque eles são dominantes, eles comandam a cena política mas não agem como “machos alfa” em termos de liderança. Liderança, e isso vale também para as mulheres, que podem ser líderes também, é juntar as partes, mantê-las unidas, preservar a ordem na sociedade e nem todos os “machos alfa” são bons nisso.
Seus livros costumam tratar das emoções dos animais e suas relações com as emoções e comportamentos humanos. Quanto nós podemos aprender com os macacos e com isso obter um comportamento melhor de nossa sociedade?
Meus livros não dizem como organizar uma sociedade humana, porque eu falo sobre bonobos, chimpanzés e outros primatas. Eu não sinto que podemos tomar lições diretamente daí. Mas o que eu posso dizer é que a psicologia humana é muito antiga. Nós costumamos pensar que inventamos tudo. De fato nós inventamos muitas coisas de tecnologia: o telefone celular, o avião etc. Mas nosso comportamento e nossa psicologia são muito antigos. Então, a mensagem dos meus livros é que muitas das tendências que nós temos são ancestrais, elas são como as dos primatas. E nesse sentido é que podemos aprender com os primatas. Podemos aprender que em suas comunidades eles resolvem conflitos, são muito bons em se reconciliar depois, em dividir alimentos… Essas são coisas que podemos aprender com os animais.
Seu livro “A Era da Empatia” me deixou a impressão de que o senhor tem o desejo de empoderar o lado bonobo que temos dentro de nós humanos. Estou certo?
Empatia é uma característica muito antiga dos mamíferos. Muitos mamíferos têm empatia, seu cachorro tem empatia. Os cientistas fizeram experiências: pediram para os adultos em uma família chorarem, para observar como os cachorros e as crianças reagem. E ambos reagem procurando se aproximar da pessoa que está chorando para consolá-la e dar conforto. Essa é uma atitude de empatia que podemos observar em todos os mamíferos. Nós humanos temos uma enorme capacidade de exercer a empatia, mas às vezes nos esquecemos disso. Especialmente, com estranhos, com gente de fora de nosso círculo, nós às vezes não revelamos esse tipo de empatia.
Falando da cena que serve de título a seu livro, o abraço final da chimpanzé Mama e do cientista que ela conheceu a vida toda: ela sabia que estava morrendo, que iria morrer em duas semanas? Os chimpanzés enfrentam a morte?
Nesta cena, meu professor, Jan van Hooff, com oitenta anos, se aproximou da chimpanzé Mama, que estava com 59 anos e estava morrendo. Ele entrou em sua jaula; ela vivia em uma área grande, com um grande grupo de chimpanzés, mas dormia em uma jaula. Ele entrou na jaula, o que nós nunca, nunca fazemos porque os macacos são muito mais fortes do que nós. Mas ele fez isso, porque ela estava morrendo. E ela o cumprimentou com um abraço. Ele sabia que ela iria morrer, estava muito fraca, e nós a conhecíamos muito bem. E ela logo o acolheu, o abraçou. O professor Van Hooff entrou lá sabendo que ela estava morrendo, mas não sabemos se ela sabia que ia morrer. Nós não sabemos se os animais têm um senso de mortalidade. Ela evidentemente sabia que estava fraca, mas não podemos afirmar que ela tinha consciência da morte. O encontro era uma oportunidade do professor se despedir dela, não sabemos se ela via aquele momento do mesmo jeito. O motivo de eu trazer esse encontro para o título do livro foi porque aquele momento, além de deixar as pessoas muito emocionadas, nos deixa muito surpresos: como os gestos são parecidos com gestos humanos, como suas expressões são parecidas com humanas. E essa reação das pessoas me surpreendeu. Nós estamos dizendo há cerca de 50 anos que os bonobos e chimpanzés são muito próximos dos seres humanos; então por que as pessoas ainda se surpreendem com suas emoções e suas expressões que parece humanas? Então por isso decidi tomar essa cena para explicar que todas as expressões faciais que nós humanos temos bem como todas as emoções que temos podem ser encontradas em nossos parentes próximos, os primatas.
Em seu livro você narra a história de uma mãe chimpanzé cujo filhote morre e ela segue carregando seu corpo por um longo período. Ela achava que ele estava vivo ou fingia que ele estava vivo?
Isso acontece com frequência. Os laços entre mãe e filho são muito fortes. Então, quando a criança morre, as mães não os abandonam. Isso é verdade com humanos, com orcas e golfinhos, ocorre com os primatas. As mães carregam os corpos de seus bebês mortos com elas. Eu penso que para elas é uma forma de manter o contato com eles. Eu acho que sim, elas sabem que seus filhos morreram, elas sabem que ele está morto, mesmo assim querem mantê-los juntos. Creio que isso é se deve à força dos laços fortíssimos entre eles e essa é uma forma de tornar gradual o processo de separação.
Podemos dizer que humanos demonstram isso com fotos e outros objetos?
Entre humanos, nós esperamos que a mãe, quando o filho morre, se separe do corpo. Mas muitas mães têm a tendência de segurá-lo e provavelmente elas manifestam isso mantendo as memórias vivas. Nunca é uma separação completa. Quando perdemos uma pessoa, nunca nos separamos completamente dela.
O senhor tem um livro inédito no Brasil cujo título é uma pergunta: “Somos Inteligentes o Suficiente para Entender Como os Animais são Inteligentes” (Are We Smart Enough to Know How Smart Animals Are, 2016)? Qual é sua resposta: somos?
Há um longo tempo nas pesquisas em inteligência animal durante a qual nós, humanos, apresentamos desafios muito simples para os animais. Tipo: colocamos um rato em uma caixa e o rato tem que apertar várias vezes uma alavanca para receber recompensas por isso e essa é a forma como testamos sua inteligência. Mas o rato é um animal muito mais inteligente do que isso, ele pode fazer muito mais coisas do que apertar uma alavanca. Então, nós não temos sido muito inteligentes no jeito de testar a inteligência animal. Especialmente com os macacos, os elefantes, os golfinhos, esses animais muito inteligentes, nós não devemos submetê-los a testes simples, devemos fazer testes apropriados para suas capacidades. Algumas vezes é muito difícil; por exemplo, a capacidade do olfato de um elefante é cem vezes maior do que a de um cachorro, que é cem vezes melhor do que nós somos. Então, temos que fazer testes que desafiem o olfato do elefante, mas isso é muito difícil criarmos, porque somos uma espécie muito visual. É complicado para os humanos trabalharem no mesmo nível das capacidades desses animais.
O sermos visuais e verbais reduz as outras dimensões de nossa inteligência?
Sim. Por exemplo, o senso de localização dos morcegos, que permite que eles voem no escuro e capturem insetos, é uma capacidade muito complexa, mas nós humanos não somos muito interessados nisso. Nós somos interessados no uso de ferramentas, em linguagens, porque somos muito bons nisso. As coisas que os morcegos fazem não nos interessam muito, porque não temos essas capacidades. Nós humanos somos muito antropocêntricos, temos viés humanos, admiramos como somos inteligentes. Então, pesquisamos o uso de ferramentas e as linguagens dos outros animais, porque somos bons nisso.
O senso comum criado pela influência das religiões diz que a linguagem é um monopólio do homem, um dom concedido unicamente ao homem. O senhor diria que nos próximos 25 anos poderemos ter surpresas nesse campo, quanto à capacidade de comunicação dos outros seres vivos?
Os animais nos têm surpreendido ao longo dos últimos 25 anos. Todos os tipos de domínios, todos os estudos têm demonstrado isso. E há animais que têm formas de comunicação muito complexas, mesmo que não sejam como a nossa linguagem, mas tipos diferentes. Por exemplo: golfinhos têm muitos sons, embaixo d’água, que nós humanos temos dificuldade de ouvir, mas com sensores temos condições de ouvir e gravar, que revelam uma comunicação complexa. E quem consegue entender o que está acontecendo ali? Por isso, eu creio que sim, vamos nos surpreender com as descobertas que faremos sobre a sofisticação da comunicação de outros animais, que pode não ser exatamente como a linguagem humana mas ser muito complexa. Então, eu não creio que sejamos os únicos animais com capacidade de comunicar coisas complicadas uns para os outros.
O senhor tem um vídeo muito popular no Youtube que mostra um macaco que se irrita por ter recebido uma recompensa pior que outro indivíduo ao realizar a mesma tarefa. Lutar por justiça é uma característica primata, antes de ser humana?
Nesse vídeo há dois macacos-prego, que é uma espécie que existe no Brasil, um recebe passas ao realizar a tarefa e o outro recebe pedaços de pepino cortado. Normalmente, se você dá pepinos aos dois macacos, eles vão achar ótimo. Mas se você dá passas a um e pepino para o outro, o que recebe o pepino vai ficar muito bravo. Nós chamamos isso de aversão pela desigualdade mas você pode chamar de senso de justiça. Eles são sensíveis quanto ao que recebem pelo que realizam, em comparação com o que outra pessoa recebe. Eu creio que isso é a raiz do senso de justiça na sociedade humana. Nós também ficamos irritados se alguém ganha um pagamento maior pelo mesmo trabalho.
O senhor já está trabalhando em um novo livro?
Sim, estou trabalhando em um livro sobre gênero, as diferenças entre os sexos. Em todos os primatas vemos diferenças, como nas sociedades humanas. Eu estou estudando isso.
Há outras espécies de primatas em que se pode encontrar mais de dois gêneros?
Sim, há sempre indivíduos em sociedades primatas que são diferentes dos outros. Por exemplo: fêmeas que agem mais como machos ou machos que agem mais como fêmeas; há também indivíduos que não se encaixam em nenhum desses estereótipos. Então, de fato, tipos de diferenças que observamos na sociedade humana aparecem também em outros animais.
Então podemos aprender também com os outros primatas sobre respeito aos transgêneros?
Eu também escrevi sobre homossexualidade entre os primatas. O mais interessante para mim é que eles toleram qualquer comportamento, sem qualquer problema. Eles não criam agitação em torno do assunto, não é uma questão importante. Se você tem um indivíduo em uma sociedade que não se comporta como outros machos do grupo, ninguém vai se perturbar por isso. Creio que nós humanos podemos aprender muito sobre tolerância com eles, sim.
Could the way drosophila use antennae to sense heat help us teach self-driving cars make decisions?
Date: April 6, 2021
Source: Northwestern University
Summary: With over 70% of respondents to a AAA annual survey on autonomous driving reporting they would fear being in a fully self-driving car, makers like Tesla may be back to the drawing board before rolling out fully autonomous self-driving systems. But new research shows us we may be better off putting fruit flies behind the wheel instead of robots.
With over 70% of respondents to a AAA annual survey on autonomous driving reporting they would fear being in a fully self-driving car, makers like Tesla may be back to the drawing board before rolling out fully autonomous self-driving systems. But new research from Northwestern University shows us we may be better off putting fruit flies behind the wheel instead of robots.
Drosophila have been subjects of science as long as humans have been running experiments in labs. But given their size, it’s easy to wonder what can be learned by observing them. Research published today in the journal Nature Communications demonstrates that fruit flies use decision-making, learning and memory to perform simple functions like escaping heat. And researchers are using this understanding to challenge the way we think about self-driving cars.
“The discovery that flexible decision-making, learning and memory are used by flies during such a simple navigational task is both novel and surprising,” said Marco Gallio, the corresponding author on the study. “It may make us rethink what we need to do to program safe and flexible self-driving vehicles.”
According to Gallio, an associate professor of neurobiology in the Weinberg College of Arts and Sciences, the questions behind this study are similar to those vexing engineers building cars that move on their own. How does a fruit fly (or a car) cope with novelty? How can we build a car that is flexibly able to adapt to new conditions?
This discovery reveals brain functions in the household pest that are typically associated with more complex brains like those of mice and humans.
“Animal behavior, especially that of insects, is often considered largely fixed and hard-wired — like machines,” Gallio said. “Most people have a hard time imagining that animals as different from us as a fruit fly may possess complex brain functions, such as the ability to learn, remember or make decisions.”
To study how fruit flies tend to escape heat, the Gallio lab built a tiny plastic chamber with four floor tiles whose temperatures could be independently controlled and confined flies inside. They then used high-resolution video recordings to map how a fly reacted when it encountered a boundary between a warm tile and a cool tile. They found flies were remarkably good at treating heat boundaries as invisible barriers to avoid pain or harm.
Using real measurements, the team created a 3D model to estimate the exact temperature of each part of the fly’s tiny body throughout the experiment. During other trials, they opened a window in the fly’s head and recorded brain activity in neurons that process external temperature signals.
Miguel Simões, a postdoctoral fellow in the Gallio lab and co-first author of the study, said flies are able to determine with remarkable accuracy if the best path to thermal safety is to the left or right. Mapping the direction of escape, Simões said flies “nearly always” escape left when they approach from the right, “like a tennis ball bouncing off a wall.”
“When flies encounter heat, they have to make a rapid decision,” Simões said. “Is it safe to continue, or should it turn back? This decision is highly dependent on how dangerous the temperature is on the other side.”
Observing the simple response reminded the scientists of one of the classic concepts in early robotics.
“In his famous book, the cyberneticist Valentino Braitenberg imagined simple models made of sensors and motors that could come close to reproducing animal behavior,” said Josh Levy, an applied math graduate student and a member of the labs of Gallio and applied math professor William Kath. “The vehicles are a combination of simple wires, but the resulting behavior appears complex and even intelligent.”
Braitenberg argued that much of animal behavior could be explained by the same principles. But does that mean fly behavior is as predictable as that of one of Braitenberg’s imagined robots?
The Northwestern team built a vehicle using a computer simulation of fly behavior with the same wiring and algorithm as a Braitenberg vehicle to see how closely they could replicate animal behavior. After running model race simulations, the team ran a natural selection process of sorts, choosing the cars that did best and mutating them slightly before recombining them with other high-performing vehicles. Levy ran 500 generations of evolution in the powerful NU computing cluster, building cars they ultimately hoped would do as well as flies at escaping the virtual heat.
This simulation demonstrated that “hard-wired” vehicles eventually evolved to perform nearly as well as flies. But while real flies continued to improve performance over time and learn to adopt better strategies to become more efficient, the vehicles remain “dumb” and inflexible. The researchers also discovered that even as flies performed the simple task of escaping the heat, fly behavior remains somewhat unpredictable, leaving space for individual decisions. Finally, the scientists observed that while flies missing an antenna adapt and figure out new strategies to escape heat, vehicles “damaged” in the same way are unable to cope with the new situation and turn in the direction of the missing part, eventually getting trapped in a spin like a dog chasing its tail.
Gallio said the idea that simple navigation contains such complexity provides fodder for future work in this area.
Work in the Gallio lab is supported by the NIH (Award No. R01NS086859 and R21EY031849), a Pew Scholars Program in the Biomedical Sciences and a McKnight Technological Innovation in Neuroscience Awards.
- José Miguel Simões, Joshua I. Levy, Emanuela E. Zaharieva, Leah T. Vinson, Peixiong Zhao, Michael H. Alpert, William L. Kath, Alessia Para, Marco Gallio. Robustness and plasticity in Drosophila heat avoidance. Nature Communications, 2021; 12 (1) DOI: 10.1038/s41467-021-22322-w
Whalers’ logbooks show rapid drop in strike rate in north Pacific due to changes in cetacean behaviour
Wed 17 Mar 2021 07.01 GMT Last modified on Thu 18 Mar 2021 14.38 GMT
A remarkable new study on how whales behaved when attacked by humans in the 19th century has implications for the way they react to changes wreaked by humans in the 21st century.
The paper, published by the Royal Society on Wednesday, is authored by Hal Whitehead and Luke Rendell, pre-eminent scientists working with cetaceans, and Tim D Smith, a data scientist, and their research addresses an age-old question: if whales are so smart, why did they hang around to be killed? The answer? They didn’t.
Using newly digitised logbooks detailing the hunting of sperm whales in the north Pacific, the authors discovered that within just a few years, the strike rate of the whalers’ harpoons fell by 58%. This simple fact leads to an astonishing conclusion: that information about what was happening to them was being collectively shared among the whales, who made vital changes to their behaviour. As their culture made fatal first contact with ours, they learned quickly from their mistakes.
“Sperm whales have a traditional way of reacting to attacks from orca,” notes Hal Whitehead, who spoke to the Guardian from his house overlooking the ocean in Halifax, Nova Scotia, where he teaches at Dalhousie University. Before humans, orca were their only predators, against whom sperm whales form defensive circles, their powerful tails held outwards to keep their assailants at bay. But such techniques “just made it easier for the whalers to slaughter them”, says Whitehead.
It was a frighteningly rapid killing, and it accompanied other threats to the ironically named Pacific. From whaling and sealing stations to missionary bases, western culture was imported to an ocean that had remained largely untouched. As Herman Melville, himself a whaler in the Pacific in 1841, would write in Moby-Dick (1851): “The moot point is, whether Leviathan can long endure so wide a chase, and so remorseless a havoc.”
Sperm whales are highly socialised animals, able to communicate over great distances. They associate in clans defined by the dialect pattern of their sonar clicks. Their culture is matrilinear, and information about the new dangers may have been passed on in the same way whale matriarchs share knowledge about feeding grounds. Sperm whales also possess the largest brain on the planet. It is not hard to imagine that they understood what was happening to them.
The hunters themselves realised the whales’ efforts to escape. They saw that the animals appeared to communicate the threat within their attacked groups. Abandoning their usual defensive formations, the whales swam upwind to escape the hunters’ ships, themselves wind-powered. ‘This was cultural evolution, much too fast for genetic evolution,’ says Whitehead.
And in turn, it evokes another irony. Now, just as whales are beginning to recover from the industrial destruction by 20th-century whaling fleets – whose steamships and grenade harpoons no whale could evade – they face new threats created by our technology. ‘They’re having to learn not to get hit by ships, cope with the depredations of longline fishing, the changing source of their food due to climate change,’ says Whitehead. Perhaps the greatest modern peril is noise pollution, one they can do nothing to evade.
Whitehead and Randall have written persuasively of whale culture, expressed in localised feeding techniques as whales adapt to shifting sources, or in subtle changes in humpback song whose meaning remains mysterious. The same sort of urgent social learning the animals experienced in the whale wars of two centuries ago is reflected in the way they negotiate today’s uncertain world and what we’ve done to it.
As Whitehead observes, whale culture is many millions of years older than ours. Perhaps we need to learn from them as they learned from us. After all, it was the whales that provoked Melville to his prophesies in Moby-Dick. “We account the whale immortal in his species, however perishable in individuality,” he wrote, “and if ever the world is to be again flooded … then the eternal whale will still survive, and … spout his frothed defiance to the skies.”
• This article was amended on 18 March 2021 to make clear the status of “Dalhousie” as a university, not a placename.
Andreas Nieder, September 7, 2020
(Credit: Press Association)
Humans as a species are adept at using numbers, but our mathematical ability is something we share with a surprising array of other creatures.
One of the key findings over the past decades is that our number faculty is deeply rooted in our biological ancestry, and not based on our ability to use language. Considering the multitude of situations in which we humans use numerical information, life without numbers is inconceivable.
But what was the benefit of numerical competence for our ancestors, before they became Homo sapiens? Why would animals crunch numbers in the first place?
It turns out that processing numbers offers a significant benefit for survival, which is why this behavioural trait is present in many animal populations. Several studies examining animals in their ecological environments suggest that representing numbers enhances an animal’s ability to exploit food sources, hunt prey, avoid predation, navigate its habitat, and persist in social interactions.
Before numerically competent animals evolved on the planet, single-celled microscopic bacteria – the oldest living organisms on Earth – already exploited quantitative information. The way bacteria make a living is through their consumption of nutrients from their environment. Mostly, they grow and divide themselves to multiply. However, in recent years, microbiologists have discovered they also have a social life and are able to sense the presence or absence of other bacteria. In other words, they can sense the number of bacteria.
Take, for example, the marine bacterium Vibrio fischeri. It has a special property that allows it to produce light through a process called bioluminescence, similar to how fireflies give off light. If these bacteria are in dilute water solutions (where they are essentially alone), they make no light. But when they grow to a certain cell number of bacteria, all of them produce light simultaneously. Therefore, Vibrio fischeri can distinguish when they are alone and when they are together.
Sometimes the numbers don’t add up when predators are trying to work out which prey to target (Credit: Alamy)
It turns out they do this using a chemical language. They secrete communication molecules, and the concentration of these molecules in the water increases in proportion to the cell number. And when this molecule hits a certain amount, called a “quorum”, it tells the other bacteria how many neighbours there are, and all the bacteria glow.
This behaviour is called “quorum sensing” – the bacteria vote with signalling molecules, the vote gets counted, and if a certain threshold (the quorum) is reached, every bacterium responds. This behaviour is not just an anomaly of Vibrio fischeri – all bacteria use this sort of quorum sensing to communicate their cell number in an indirect way via signalling molecules.
Remarkably, quorum sensing is not confined to bacteria – animals use it to get around, too. Japanese ants (Myrmecina nipponica), for example, decide to move their colony to a new location if they sense a quorum. In this form of consensus decision making, ants start to transport their brood together with the entire colony to a new site only if a defined number of ants are present at the destination site. Only then, they decide, is it safe to move the colony.
Numerical cognition also plays a vital role when it comes to both navigation and developing efficient foraging strategies. In 2008, biologists Marie Dacke and Mandyam Srinivasan performed an elegant and thoroughly controlled experiment in which they found that bees are able to estimate the number of landmarks in a flight tunnel to reach a food source – even when the spatial layout is changed. Honeybees rely on landmarks to measure the distance of a food source to the hive. Assessing numbers is vital to their survival.
When it comes to optimal foraging, “going for more” is a good rule of thumb in most cases, and seems obvious when you think about it, but sometimes the opposite strategy is favourable. The field mouse loves live ants, but ants are dangerous prey because they bite when threatened. When a field mouse is placed into an arena together with two ant groups of different quantities, then, it surprisingly “goes for less”. In one study, mice that could choose between five versus 15, five versus 30, and 10 versus 30 ants always preferred the smaller quantity of ants. The field mice seem to pick the smaller ant group in order to ensure comfortable hunting and to avoid getting bitten frequently.
Numerical cues play a significant role when it comes to hunting prey in groups, as well. The probability, for example, that wolves capture elk or bison varies with the group size of a hunting party. Wolves often hunt large prey, such as elk and bison, but large prey can kick, gore, and stomp wolves to death. Therefore, there is incentive to “hold back” and let others go in for the kill, particularly in larger hunting parties. As a consequence, wolves have an optimal group size for hunting different prey. For elks, capture success levels off at two to six wolves. However, for bison, the most formidable prey, nine to 13 wolves are the best guarantor of success. Therefore, for wolves, there is “strength in numbers” during hunting, but only up to a certain number that is dependent on the toughness of their prey.
Animals that are more or less defenceless often seek shelter among large groups of social companions – the strength-in-numbers survival strategy hardly needs explaining. But hiding out in large groups is not the only anti-predation strategy involving numerical competence.
In 2005, a team of biologists at the University of Washington found that black-capped chickadees in Europe developed a surprising way to announce the presence and dangerousness of a predator. Like many other animals, chickadees produce alarm calls when they detect a potential predator, such as a hawk, to warn their fellow chickadees. For stationary predators, these little songbirds use their namesake “chick-a-dee” alarm call. It has been shown that the number of “dee” notes at the end of this alarm call indicates the danger level of a predator.
Chickadees produce different numbers of “dee” notes at the end of their call depending on danger they have spotted (Credit: Getty Images)
A call such as “chick-a-dee-dee” with only two “dee” notes may indicate a rather harmless great grey owl. Great grey owls are too big to manoeuvre and follow the agile chickadees in woodland, so they aren’t a serious threat. In contrast, manoeuvring between trees is no problem for the small pygmy owl, which is why it is one of the most dangerous predators for these small birds. When chickadees see a pygmy owl, they increase the number of “dee” notes and call “chick-a-dee-dee-dee-dee.” Here, the number of sounds serves as an active anti-predation strategy.
Groups and group size also matter if resources cannot be defended by individuals alone – and the ability to assess the number of individuals in one’s own group relative to the opponent party is of clear adaptive value.
Several mammalian species have been investigated in the wild, and the common finding is that numerical advantage determines the outcome of such fights. In a pioneering study, zoologist Karen McComb and co-workers at the University of Sussex investigated the spontaneous behaviour of female lions at the Serengeti National Park when facing intruders. The authors exploited the fact that wild animals respond to vocalisations played through a speaker as though real individuals were present. If the playback sounds like a foreign lion that poses a threat, the lionesses would aggressively approach the speaker as the source of the enemy. In this acoustic playback study, the authors mimicked hostile intrusion by playing the roaring of unfamiliar lionesses to residents.
Two conditions were presented to subjects: either the recordings of single female lions roaring, or of groups of three females roaring together. The researchers were curious to see if the number of attackers and the number of defenders would have an impact on the defender’s strategy. Interestingly, a single defending female was very hesitant to approach the playbacks of a single or three intruders. However, three defenders readily approached the roaring of a single intruder, but not the roaring of three intruders together.
Obviously, the risk of getting hurt when entering a fight with three opponents was foreboding. Only if the number of the residents was five or more did the lionesses approach the roars of three intruders. In other words, lionesses decide to approach intruders aggressively only if they outnumber the latter – another clear example of an animal’s ability to take quantitative information into account.
Our closest cousins in the animal kingdom, the chimpanzees, show a very similar pattern of behaviour. Using a similar playback approach, Michael Wilson and colleagues from Harvard University found that the chimpanzees behaved like military strategists. They intuitively follow equations used by military forces to calculate the relative strengths of opponent parties. In particular, chimpanzees follow predictions made in Lanchester’s “square law” model of combat. This model predicts that, in contests with multiple individuals on each side, chimpanzees in this population should be willing to enter a contest only if they outnumber the opposing side by a factor of at least 1.5. And that is precisely what wild chimps do.
Lionesses judge how many intruders they may be facing before approaching them (Credit: Alamy)
Staying alive – from a biological stance – is a means to an end, and the aim is the transmission of genes. In mealworm beetles (Tenebrio molitor), many males mate with many females, and competition is intense. Therefore, a male beetle will always go for more females in order to maximise his mating opportunities. After mating, males even guard females for some time to prevent further mating acts from other males. The more rivals a male has encountered before mating, the longer he will guard the female after mating.
It is obvious that such behaviour plays an important role in reproduction and therefore has a high adaptive value. Being able to estimate quantity has improved males’ sexual competitiveness. This may in turn be a driving force for more sophisticated cognitive quantity estimation throughout evolution.
One may think that everything is won by successful copulation. But that is far from the truth for some animals, for whom the real prize is fertilising an egg. Once the individual male mating partners have accomplished their part in the play, the sperm continues to compete for the fertilisation of the egg. Since reproduction is of paramount importance in biology, sperm competition causes a variety of adaptations at the behavioural level.
In both insects and vertebrates, the males’ ability to estimate the magnitude of competition determines the size and composition of the ejaculate. In the pseudoscorpion, Cordylochernes scorpioides, for example, it is common that several males copulate with a single female. Obviously, the first male has the best chances of fertilising this female’s egg, whereas the following males face slimmer and slimmer chances of fathering offspring. However, the production of sperm is costly, so the allocation of sperm is weighed considering the chances of fertilising an egg.
Males smell the number of competitor males that have copulated with a female and adjust by progressively decreasing sperm allocation as the number of different male olfactory cues increases from zero to three.
Some bird species, meanwhile, have invented a whole arsenal of trickery to get rid of the burden of parenthood and let others do the job. Breeding a clutch and raising young are costly endeavours, after all. They become brood parasites by laying their eggs in other birds’ nests and letting the host do all the hard work of incubating eggs and feeding hatchlings. Naturally, the potential hosts are not pleased and do everything to avoid being exploited. And one of the defence strategies the potential host has at its disposal is the usage of numerical cues.
American coots, for example, sneak eggs into their neighbours’ nests and hope to trick them into raising the chicks. Of course, their neighbours try to avoid being exploited. A study in the coots’ natural habitat suggests that potential coot hosts can count their own eggs, which helps them to reject parasitic eggs. They typically lay an average-sized clutch of their own eggs, and later reject any surplus parasitic egg. Coots therefore seem to assess the number of their own eggs and ignore any others.
An even more sophisticated type of brood parasitism is found in cowbirds, a songbird species that lives in North America. In this species, females also deposit their eggs in the nests of a variety of host species, from birds as small as kinglets to those as large as meadowlarks, and they have to be smart in order to guarantee that their future young have a bright future.
Cowbird eggs hatch after exactly 12 days of incubation; if incubation is only 11 days, the chicks do not hatch and are lost. It is therefore not an accident that the incubation times for the eggs of the most common hosts range from 11 to 16 days, with an average of 12 days. Host birds usually lay one egg per day – once one day elapses with no egg added by the host to the nest, the host has begun incubation. This means the chicks start to develop in the eggs, and the clock begins ticking. For a cowbird female, it is therefore not only important to find a suitable host, but also to precisely time their egg laying appropriately. If the cowbird lays her egg too early in the host nest, she risks her egg being discovered and destroyed. But if she lays her egg too late, incubation time will have expired before her cowbird chick can hatch.
Female cowbirds perform some incredible mental arithmetic to know when she should lay her eggs in the next of a host bird (Credit: Alamy)
Clever experiments by David J White and Grace Freed-Brown from the University of Pennsylvania suggest that cowbird females carefully monitor the host’s clutch to synchronise their parasitism with a potential host’s incubation. The cowbird females watch out for host nests in which the number of eggs has increased since her first visit. This guarantees that the host is still in the laying process and incubation has not yet started. In addition, the cowbird is looking out for nests that contain exactly one additional egg per number of days that have elapsed since her initial visit.
For instance, if the cowbird female visited a nest on the first day and found one host egg in the nest, she will only deposit her own egg if the host nest contains three eggs on the third day. If the nest contains fewer additional eggs than the number of days that have passed since the last visit, she knows that incubation has already started and it is useless for her to lay her own egg. It is incredibly cognitively demanding, since the female cowbird needs to visit a nest over multiple days, remember the clutch size from one day to the next, evaluate the change in the number of eggs in the nest from a past visit to the present, assess the number of days that have passed, and then compare these values to make a decision to lay her egg or not.
But this is not all. Cowbird mothers also have sinister reinforcement strategies. They keep watch on the nests where they’ve laid their eggs. In an attempt to protect their egg, the cowbirds act like mafia gangsters. If the cowbird finds that her egg has been destroyed or removed from the host’s nest, she retaliates by destroying the host bird’s eggs, pecking holes in them or carrying them out of the nest and dropping them on the ground. The host birds better raise the cowbird nestling, or else they have to pay dearly. For the host parents, it may therefore be worth to go through all the trouble of raising a foster chick from an adaptive point of view.
The cowbird is an astounding example of how far evolution has driven some species to stay in the business of passing on their genes. The existing selection pressures, whether imposed by the inanimate environment or by other animals, force populations of species to maintain or increase adaptive traits caused by specific genes. If assessing numbers helps in this struggle to survive and reproduce, it surely is appreciated and relied on.
This explains why numerical competence is so widespread in the animal kingdom: it evolved either because it was discovered by a previous common ancestor and passed on to all descendants, or because it was invented across different branches of the animal tree of life.
Irrespective of its evolutionary origin, one thing is certain – numerical competence is most certainly an adaptive trait.
* This article originally appeared in The MIT Press Reader, and is republished under a Creative Commons licence. Andreas Nieder is Professor of Animal Physiology and Director of the Institute of Neurobiology at the University of Tübingen and the author of A Brain for Numbers, from which this article is adapted.
Arctic people have been communicating with cetaceans for centuries—and scientists are finally taking note.
Harry Brower Sr. was lying in a hospital bed in Anchorage, Alaska, close to death, when he was visited by a baby whale.
Although Brower’s body remained in Anchorage, the young bowhead took him more than 1,000 kilometers north to Barrow (now Utqiaġvik), where Brower’s family lived. They traveled together through the town and past the indistinct edge where the tundra gives way to the Arctic Ocean. There, in the ice-blue underwater world, Brower saw Iñupiat hunters in a sealskin boat closing in on the calf’s mother.
Brower felt the shuddering harpoon enter the whale’s body. He looked at the faces of the men in the umiak, including those of his own sons. When he awoke in his hospital bed as if from a trance, he knew precisely which man had made the kill, how the whale had died, and whose ice cellar the meat was stored in. He turned out to be right on all three counts.
Brower lived six years after the episode, dying in 1992 at the age of 67. In his final years, he discussed what he had witnessed with Christian ministers and Utqiaġvik’s whaling captains. The conversations ultimately led him to hand down new rules to govern hunting female whales with offspring, meant to communicate respect to whales and signal that people were aware of their feelings and needs. “[The whale] talked to me,” Brower recalls in a collection of his stories, The Whales, They Give Themselves. “He told me all the stories about where they had all this trouble out there on the ice.”
Not long ago, non-Indigenous scientists might have dismissed Brower’s experience as a dream or the inchoate ramblings of a sick man. But he and other Iñupiat are part of a deep history of Arctic and subarctic peoples who believe humans and whales can talk and share a reciprocal relationship that goes far beyond that of predator and prey. Today, as Western scientists try to better understand Indigenous peoples’ relationships with animals—as well as animals’ own capacity for thoughts and feelings—such beliefs are gaining wider recognition, giving archaeologists a better understanding of ancient northern cultures.
“If you start looking at the relationship between humans and animals from the perspective that Indigenous people themselves may have had, it reveals a rich new universe,” says Matthew Betts, an archaeologist with the Canadian Museum of History who studies Paleo-Eskimo cultures in the Canadian Arctic. “What a beautiful way to view the world.”
It’s not clear exactly when people developed the technology that allowed them to begin hunting whales, but scholars generally believe Arctic whaling developed off the coast of Alaska sometime between 600 and 800 CE. For thousands of years before then, Arctic people survived by hunting seals, caribou, and walruses at the edge of the sea ice.
One such group, the Dorset—known in Inuit oral tradition as the Tunit—were rumored to have been so strong the men could outrun caribou and drag a 1,700-kilogram walrus across the ice. The women were said to have fermented raw seal meat against the warmth of their skin, leaving it in their pants for days at a time. But despite their legendary survival skills, the Tunit died out 1,000 years ago.
An Inuit hunter sits on a whale that’s been hauled to shore for butchering in Point Hope, Alaska, in 1900. Photo by Hulton Deutsch/Getty Images
One theory for their mysterious disappearance is that they were outcompeted by people who had begun to move east into the Canadian Arctic—migrants from Alaska who brought sealskin boats allowing them to push off from shore and hunt whales. Each spring, bowhead whales weighing up to 54,000 kilograms pass through the leads of water that open into the sea ice, and with skill and luck, the ancestors of today’s Inuit and Iñupiat people could spear a cetacean as it surfaced to breathe.
The advent of whaling changed the North. For the first time, hunters could bring in enough meat to feed an entire village. Permanent settlements began springing up in places like Utqiaġvik that were reliably visited by bowheads—places still inhabited today. Social organizations shifted as successful whale hunters amassed wealth, became captains, and positioned themselves at the top of a developing social hierarchy. Before long, the whale hunt became the center of cultural, spiritual, and day-to-day life, and whales the cornerstone of many Arctic and subarctic cosmologies.
When agricultural Europeans began visiting and writing about the North in the 10th century, they were mesmerized by Aboriginal peoples’ relationships with whales. Medieval literature depicted the Arctic as a land of malevolent “monstrous fishes” and people who could summon them to shore through magical powers and mumbled spells. Even as explorers and missionaries brought back straightforward accounts of how individual whaling cultures went about hunting, butchering, and sharing a whale, it was hard to shake the sense of mysticism. In 1938, American anthropologist Margaret Lantis analyzed these scattered ethnographic accounts and concluded that Iñupiat, Inuit, and other northern peoples belonged to a circumpolar “whale cult.”
Lantis found evidence of this in widespread taboos and rituals meant to cement the relationship between people and whales. In many places, a recently killed whale was given a drink of fresh water, a meal, and even traveling bags to ensure a safe journey back to its spiritual home. Individual whalers had their own songs to call the whales to them. Sometimes shamans performed religious ceremonies inside circles made of whale bones. Stashes of whaling amulets—an ambiguous word used to describe everything from carved, jewelry-like charms to feathers or skulls—were passed from father to son in whaling families.
To non-Indigenous observers, it was all so mysterious. So unknowable. And for archaeologists and biologists especially, it was at odds with Western scientific values, which prohibited anything that smacked of anthropomorphism.
A whaler waits for the bowhead whales from shore in Utqiaġvik, Alaska, during whaling season in the Chukchi Sea. Photo by Steven J. Kazlowski/Alamy Stock Photo
In archaeology, such attitudes have limited our understanding of Arctic prehistory, says Erica Hill, a zooarchaeologist with the University of Alaska Southeast. Whaling amulets and bone circles were written off as ritualistic or supernatural with little exploration of what they actually meant to the people who created them. Instead, archaeologists who studied animal artifacts often focused on the tangible information they revealed about what ancient people ate, how many calories they consumed, and how they survived.
Hill is part of a burgeoning branch of archaeology that uses ethnographic accounts and oral histories to re-examine animal artifacts with fresh eyes—and interpret the past in new, non-Western ways. “I’m interested in this as part of our prehistory as humans,” Hill says, “but also in what it tells us about alternative ways of being.”
The idea that Indigenous people have spiritual relationships with animals is so well established in popular culture it’s cliché. Yet constricted by Western science and culture, few archaeologists have examined the record of human history with the perspective that animals feel emotions and can express those emotions to humans.
Hill’s interest in doing so was piqued in 2007, when she was excavating in Chukotka, Russia, just across the Bering Strait from Alaska. The site was estimated to be 1,000 to 2,000 years old, predating the dawn of whaling in the region, and was situated at the top of a large hill. As her team dug through the tundra, they uncovered six or seven intact walrus skulls deliberately arranged in a circle.
Like many archaeologists, Hill had been taught that ancient humans in harsh northern climates conserved calories and rarely expended energy doing things with no direct physical benefit. That people were hauling walrus skulls to a hilltop where there were plenty of similar-sized rocks for building seemed strange. “If you’ve ever picked up a walrus skull, they’re really, really heavy,” Hill says. So she started wondering: did the skulls serve a purpose that wasn’t strictly practical that justified the effort of carrying them uphill?
When Hill returned home, she began looking for other cases of “people doing funky stuff” with animal remains. There was no shortage of examples: shrines packed with sheep skulls, ceremonial burials of wolves and dogs, walrus-skull rings on both sides of the Bering Strait. To Hill, though, some of the most compelling artifacts came from whaling cultures.
Museum collections across North America, for instance, include a dazzling array of objects categorized as whaling amulets. From this grab bag, Hill identified 20 carved wooden objects. Many served as the seats of whaling boats. In the Iñupiaq language, they’re called either iktuġat or aqutim aksivautana, depending on dialect.
One in particular stands out. Hill was looking for Alaskan artifacts in a massive climate-controlled warehouse belonging to Smithsonian’s National Museum of Natural History in Washington, DC. The artifacts were housed in hundreds of floor-to-ceiling drawers, row after row of them, with little indication of what was inside. She pulled open one drawer and there it was—the perfect likeness of a bowhead whale staring back at her.
The object, likely from the late 19th century, probably functioned as a crosspiece. It was hewn from a hunk of driftwood into a crescent shape 21 centimeters long. Carved on one side was a bowhead, looking as it would look if you were gazing down on a whale from above, perhaps from a raven’s-eye perspective. A precious bead of obsidian was embedded in the blowhole. “It’s so elegant and simple but so completely whale,” Hill says. “It’s this perfect balance of minimalism and form.”
Sometime in the late 19th century, an Iñupiaq carver fashioned this amulet for an umiak out of driftwood, carving the likeness of a bowhead whale, its blowhole symbolized with a piece of obsidian. As with other whaling amulets Erica Hill has examined, this object may have also functioned as part of the boat’s structure. Photo by Department of Anthropology, Smithsonian Institute (Cat. A347918)
Using Iñupiat oral histories and ethnographies recorded in the 19th and 20th centuries, Hill now knows that such amulets were meant to be placed in a boat with the likeness of the whale facing down, toward the ocean. The meticulously rendered art was thus meant not for humans, but for whales—to flatter them, Hill says, and call them to the hunters. “The idea is that the whale will be attracted to its own likeness, so obviously you want to depict the whale in the most positive way possible,” she explains.
Yupik stories from St. Lawrence Island tell of whales who might spend an hour swimming directly under an umiak, positioning themselves so they could check out the carvings and the men occupying the boat. If the umiak was clean, the carvings beautiful, and the men respectful, the whale might reposition itself to be harpooned. If the art portrayed the whale in an unflattering light or the boat was dirty, it indicated that the hunters were lazy and wouldn’t treat the whale’s body properly. Then the whale might swim away.
In “Sounding a Sea-Change: Acoustic Ecology and Arctic Ocean Governance” published in Thinking with Water, Shirley Roburn quotes Point Hope, Alaska, resident Kirk Oviok: “Like my aunt said, the whales have ears and are more like people,” he says. “The first batch of whales seen would show up to check which ones in the whaling crew would be more hospitable. … Then the whales would come back to their pack and tell them about the situation.”
The belief that whales have agency and can communicate their needs to people isn’t unique to the Arctic. Farther south, on Washington’s Olympic Peninsula and British Columbia’s Vancouver Island, Makah and Nuu-chah-nulth whalers observed eight months of rituals meant to communicate respect in the mysterious language of whales. They bathed in special pools, prayed, spoke quietly, and avoided startling movements that might offend whales. Right before the hunt, the whalers sang a song asking the whale to give itself.
In Makah and Nuu-chah-nulth belief, as in many Arctic cultures, whales weren’t just taken—they willingly gave themselves to human communities. A whale that offered its body wasn’t sentencing itself to death. It was choosing to be killed by hunters who had demonstrated, through good behavior and careful adherence to rituals, that they would treat its remains in a way that would allow it to be reborn. Yupik tradition, for example, holds that beluga whales once lived on land and long to return to terra firma. In exchange for offering itself to a Yupik community, a beluga expected to have its bones given the ritualistic treatment that would allow it to complete this transition and return to land, perhaps as one of the wolves that would gnaw on the whale’s bones.
According to Hill, many of the objects aiding this reciprocity—vessels used to offer whales a drink of fresh water, amulets that hunters used to negotiate relationships with animal spirits—weren’t just reserved for shamanistic ceremonies. They were part of everyday life; the physical manifestation of an ongoing, daily dialogue between the human and animal worlds.
While Westerners domesticated and eventually industrialized the animals we eat—and thus came to view them as dumb and inferior—Arctic cultures saw whale hunting as a match between equals. Bipedal humans with rudimentary technology faced off against animals as much as 1,000 times their size that were emotional, thoughtful, and influenced by the same social expectations that governed human communities. In fact, whales were thought to live in an underwater society paralleling that above the sea.
It’s difficult to assess populations of animals that swim under the ice, far from view, like bowhead whales. But experienced Iñupiat whalers are good at it. Photo by Steven Kazlowski/Minden Pictures
Throughout history, similar beliefs have guided other human-animal relationships, especially in hunter-gatherer cultures that shared their environment with big, potentially dangerous animals. Carvings left behind by the Tunit, for example, suggest a belief that polar bears possessed a kind of personhood allowing them to communicate with humans; while some Inuit believed walruses could listen to humans talking about them and react accordingly.
Whether or not those beliefs are demonstrably true, says Hill, they “make room for animal intelligence and feelings and agency in ways that our traditional scientific thinking has not.”
Today, as archaeologists like Hill and Matthew Betts shift their interpretation of the past to better reflect Indigenous worldviews, biologists too are shedding new light on whale behavior and biology that seems to confirm the traits Indigenous people have attributed to whales for more than 1,000 years. Among them is Hal Whitehead, a professor at Dalhousie University in Nova Scotia who argues that cetaceans have their own culture—a word typically reserved for human societies.
By this definition, culture is social learning that’s passed down from one generation to the next. Whitehead finds evidence for his theory in numerous recent studies, including one that shows bowhead whales in the North Pacific, off the Alaskan coast, and in the Atlantic Ocean near Greenland sing different songs, the way human groups might have different styles of music or linguistic dialects. Similarly, pods of resident killer whales living in the waters off south Vancouver Island greet each other with different behaviors than killer whales living off north Vancouver Island, despite the fact that the groups are genetically almost identical and have overlapping territories.
Plus, calves spend years with their mothers, developing the strong mother-offspring bonds that serve to transfer cultural information, and bowhead whales live long enough to accumulate the kind of environmental knowledge that would be beneficial to pass on to younger generations. We know this largely because of a harpoon tip that was found embedded in a bowhead in northern Alaska in 2007. This particular harpoon was only manufactured between 1879 and 1885 and wasn’t used for long after, meaning that the whale had sustained its injury at least 117 years before it finally died.
Other beliefs, too, are proving less farfetched than they once sounded. For years, scientists believed whales couldn’t smell, despite the fact that Iñupiat hunters claimed the smell of woodsmoke would drive a whale away from their camp. Eventually, a Dutch scientist dissecting whale skulls proved the animals did, indeed, have the capacity to smell. Even the Yupik belief that beluga whales were once land-dwelling creatures is rooted in reality: some 50 million years ago, the ancestor of modern-day whales walked on land. As if recalling this, whale fetuses briefly develop legs before losing them again.
None of this suggests that whales freely give themselves to humans. But once you understand the biological and intellectual capabilities of whales—as whaling cultures surely did—it’s less of a leap to conclude that cetaceans live in their own underwater society, and can communicate their needs and wishes to humans willing to listen.
With the dawn of the 20th century and the encroachment of Euro-Americans into the North, Indigenous whaling changed drastically. Whaling in the Makah and Nuu-chah-nulth Nations essentially ended in the 1920s after commercial whalers hunted the gray whale to near extinction. In Chukotka, Russian authorities in the 1950s replaced community-based whaling with state-run whaling.
Even the whaling strongholds of Alaska’s Iñupiat villages weren’t immune. In the 1970s, the International Whaling Commission ordered a halt to subsistence bowhead whaling because US government scientists feared there were just 1,300 of the animals left. Harry Brower Sr. and other whaling captains who’d amassed lifetimes of knowledge knew that figure was wrong.
But unlike other whaling cultures, Iñupiat whalers had the means to fight back, thanks to taxes they had collected from a nearby oil boom. With the money, communities hired Western-trained scientists to corroborate traditional knowledge. The scientists developed a new methodology that used hydrophones to count bowhead whales beneath the ice, rather than extrapolating the population based on a count of the visible bowheads passing by a single, ice-free locale. Their findings proved bowheads were far more numerous than the government had previously thought, and subsistence whaling was allowed to continue.
Elsewhere, too, whaling traditions have slowly come back to life. In 1999, the Makah harvested their first whale in over 70 years. The Chukchi were allowed to hunt again in the 1990s.
Yet few modern men knew whales as intimately as Brower. Although he eschewed some traditions—he said he never wanted his own whaling song to call a harpooned whale to the umiak, for example—Brower had other ways of communicating with whales. He believed that whales listened, and that if a whaler was selfish or disrespectful, whales would avoid him. He believed that the natural world was alive with animals’ spirits, and that the inexplicable connection he’d felt with whales could only be explained by the presence of such spirits.
And he believed that in 1986, a baby whale visited him in an Anchorage hospital to show him how future generations could maintain the centuries-long relationship between humans and whales. Before he died, he told his biographer Karen Brewster that although he believed in a Christian heaven, he personally thought he would go elsewhere. “I’m going to go join the whales,” he said. “That’s the best place, I think. … You could feed all the people for the last time.”
Perhaps Brower did become a whale and feed his people one last time. Or perhaps, through his deep understanding of whale biology and behavior, he passed down the knowledge that enabled his people to feed themselves for generations to come. Today, the spring whaling deadline he proposed based on his conversation with the baby whale is still largely observed, and bowhead whales continue to sustain Iñupiat communities, both physically and culturally.
Correction: This article has been updated to clarify the original purpose of the whaling amulet that caught Erica Hill’s attention in the Smithsonian warehouse.
9 abril 2018
GEZA TELEKI. A eleição de um macaco do norte do Parque Nacional de Gombe como macho alfa causou tensão na comunidade de chimpanzés e, principalmente, com dois rivais, Charlie e Hugh
A única guerra civil documentada entre chimpanzés selvagens começou com um assassinato brutal.
Era janeiro de 1974, e um chimpanzé chamado Godi fazia sua refeição, sozinho, nos galhos de uma árvore no Parque Nacional de Gombe, na Tanzânia.
Mas Godi não reparou que, enquanto comia, oito macacos o rodearam. “Ele pulou da árvore e correu, mas eles o agarraram”, disse o primatologista britânico Richard Wrangham ao documentário da BBC The Demonic Ape (O Macaco Demoníaco, em tradução livre).”Um deles conseguiu agarrar um de seus pés, outro lhe prendeu pela mão. Ele foi imobilizado e surrado. O ataque durou mais de cinco minutos e, quando o deixaram, ele mal conseguia se mover.
“Godi nunca mais foi visto.
O episódio é conhecido como o início do que a famosa primatologista britânica Jane Goodall chamou de “A Guerra dos 4 Anos”, o conflito que dividiu uma comunidade de chimpanzés em Gombe e desatou uma onda de assassinatos e violência que, desde então, nunca mais foi registrada.
Macacos e humanos
Feldblum está há 25 anos arquivando e digitalizando as anotações que Goodall fez durante seus mais de 55 anos vivendo no Parque Nacional de Gombe.
A primatologista, que na última terça-feira completou 84 anos, mudou tudo o que acreditávamos saber sobre os chimpanzés (e sobre os seres humanos) ao descobrir que esses macacos fabricavam e usavam ferramentas, tinham uma linguagem primitiva e eram capazes de entender o que seus pares pensavam.
Mas Goodall também descobriu a crueldade que esses animais podiam demonstrar.
GETTY IMAGES. A primatologista Jane Goodall, que lidera uma fundação de pesquisa e conservação com seu nome, acompanhou toda a guerra dos chimpanzés nos anos 1970
Foram quatro anos documentando saques, surras e assassinatos entre as facções Kasakela e Kahama, que ficavam ao norte e ao sul do parque, respectivamente.
Nesse tempo, por exemplo, um terço das mortes de chimpanzés machos em Gombe foram perpetreadas pelos próprios animais.
A guerra, disse Goodall no documentário da BBC, “só fez com que os chimpanzés se parecessem ainda mais conosco do que se pensava”.
A violência foi tão excessiva e única que alguns investigadores sugeriram que ela foi provocada involuntariamente pela própria Goodall, que montou uma estação de observação no local onde os animais recebiam alimentos.
De acordo com essas teorias, “as duas comunidades de chimpanzés poderiam ter existido o tempo todo ou estavam se dissolvendo quando Goodall começou sua pesquisa, e a estação de alimentação os reuniu em uma trégua temporária até que eles se separaram novamente”, disse o comunicado da Universidade de Duke.
“Mas os novos resultados de uma equipe de Duke e da Universidade Estadual do Arizona sugerem que alguma coisa a mais estava acontecendo.”
Amigos e inimigos
No novo estudo, os pesquisadores analisaram as mudanças nas alianças entre 19 chimpanzés machos durante os sete anos anteriores à guerra.
Para isso, elaboraram mapas detalhados das redes sociais dos primatas, nas quais os machos eram considerados amigos se fossem vistos chegando juntos à estação de alimentação com maior frequência.
“Sua análise sugere que, durante os primeiros anos, entre 1967 e 1970, os machos do grupo original estavam misturados”, disse Duke.
Foi aí que a comunidade começou a se dividir: enquanto alguns passavam mais tempo no norte, outros estavam a maior parte do tempo no sul.
Em 1972, a socialização entre os machos já ocorria exclusivamente dentro das facções Kasakela ou Kahama.
Ao se encontrarem, eles começavam a atirar galhos uns nos outros, a gritar ou fazer outras demonstrações de força.
“Escutávamos gritos do sul e dizíamos: ‘Os machos do sul estão vindo!'”, relembra Anne Pusey, professora de antropologia evolutiva da Universidade de Duke que esteve em Gombe com Goodall e é coautora do estudo atual.
“Nessa hora, todos os machos do norte subiam nas árvores e ouvíamos muitos gritos e demonstrações de poder.”
A partir do momento que ocorreu a divisão entre os grupos, os pesquisadores acreditam que o conflito surgiu por causa de “uma luta pelo poder entre três machos de alta categoria”: Humphrey, um macho alfa recém-coroado pelo grupo do norte, e seus rivais do sul, Charlie e Hugh.
“Humphrey era grande e se sabia que ele atirava pedras, o que era assustador. Ele conseguia intimidar Charlie e Hugh separadamente, mas, quando estavam juntos, ele se mantinha fora do caminho”, diz Pussey no comunicado da universidade.
Durante quatro anos, o grupo de Humphrey destruiu o grupo do sul, e diversos machos “rebeldes” morreram ou desapareceram. O maior dos grupos invadia sistemativamente o território alheio e, se encontrasse um chimpanzé rival, o atacava cruelmente e o deixava morrer em decorrência dos ferimentos.
De acordo com a pesquisa, a disponibilidade de fêmeas foi mais baixa do que o normal nesse período, o que provavelmente exacerbou a luta pelo domínio do território.
A violência, por sua vez, não se limitou a esses três machos rivais, mas afetou toda a rede de vínculos sociais dos primatas, sem distinguir idade nem sexo.
Os pesquisadores reconhecem que a falta de outros eventos semelhantes na natureza torna mais difícil comparar os novos resultados, mas o trabalho pode trazer certa paz a Goodall.
“A situação foi terrível”, disse a britânica, reconhecendo que sua estação de observação de fato pode ter “aumentado a violência” entre os primatas.
“Acho que a parte mais triste foi ter observado a sequência de eventos em que uma comunidade maior aniquilou por completo a menor e tomou seu território.”
Abridge in cultures has occurred. A cognitive chasm between intelligent creatures has been crossed. Of all the spectacular times for you to be alive, you happen to have been born in an age when killer whales started talking to the damn dirty apes who were willing to listen. Though this sounds like some sort of sci-fi dream/nightmare, I am here to assure you that this is real. Remain calm, but stay vigilant around all marine mammals at this time. We may be in for a rocky time, as you shall discover.
Let us begin by examining the facts. First, it’s true. As you may have heard by now, a captive killer whale called Wikie, housed at Marineland in Antibes, France, is uttering noises that mimic the human sounds “Hello” and “Bye-bye” as well as “One, two, three” plus, apparently, the haunting word “Amy” – the name of its trainer. Predictably, within hours of the release of the scientific paper, Wikie has become something of an online celebrity.
This week, after the news broke about Wikie’s great feat, a number of vocal animal welfare charities were calling for her release from captivity. This troubled me a little. Really? I thought. Is that really a good idea?
Killer whales (like all dolphins) are adept at horizontal learning, after all. They copy one another. They have sounds for objects, possibly names. They have dialects. They transmit behaviours. In other words, they have culture like we do. Might the once captive Wikie somehow spoil their untamed wildness with her newly learned human vernacular? What if this captive dolphin, somehow released into the wild with a human greeting (“Hello!”) should corrupt the wild dolphins it comes across? What then? I dread to think, but the idea is entertaining to consider so let us do just that.
Let us imagine pods of wild dolphins screaming “Goodbye” at boatloads of tourists that encroach on their hunting grounds each year. Imagine them saying “Bye-bye” to trawlers. Imagine them ruining countless nature documentaries by screaming “Hello” to BBC camera crews while filming.
And what if Wikie and her kind later develop sarcasm? Can you imagine, in an age where our oceans become bereft and depleted of nutrition, the words “So long and thanks for all the fish!”, delivered in a sarcastic tone? In a perverse sort of way, I suspect Douglas Adams would have laughed long and loud at this idea. And then wept.
Listen to killer whales mimicking human voices – audio
But there are positives to this possible cross-species dialogue, and perhaps it is this potential that we should focus on. Imagine a non-human animal that could speak up – in human words – against the degradation of a vast ecosystem like that of the oceans? In such a world, perhaps modern politics would find itself a new enemy in marine mammals like Wikie. One can imagine, for instance, in some alternative universe, a language-endowed Wikie being invited to speak at Davos or some other God-awful international event.
One can imagine the soundbites (“Amy?”); the 7.45am BBC Breakfast interview; the cosy press conferences with Wikie, wide-eyed in a giant blow-up birthing pool in front of the cameras, next to a shady foreign president secretly plotting her kind’s political downfall while sipping imported water from a non-recyclable plastic bottle. (While writing this it strikes me how, in moments like these, just how so many of us would side with these talkative killer whales). But alas, such imaginative scenarios are just that – imaginative.
You knew this bit was coming. It is time to burst the bubble about this female killer whale. Wikie has a kind of magic about her, but it is not yet a two-way conversation. She is a mimic, pure and simple and she is hungry for her fish rewards. In the same way as a 14-year-old can armpit-fart his way through Bach’s Fifth Symphony to achieve 1,000-plus views on YouTube, without ever truly knowing Bach, this killer whale has hit upon a neat trick for reward by exhaling in a measured way that sounds a little like human voice.
But that doesn’t make the science hogwash. Far from it. It’s a beginning. And all scientific journeys have a beginning. We’ll need wild, untainted, unspoiled populations to test ideas on. We need to get away from fish rewards. We need to move away from captive research. This is a start. It’s not the end. They may one day talk with us, but not like this.
And so, in my wildest dreams it won’t be a “bye-bye” or a “hello” that curries favour with an intelligent species such as the killer whale, but a word of more depth: a word like “friend” or “partner” or “respect”. And further down the line maybe we could manage something else. Dialogue. Truth. Meaning.
As of recent times, these are no longer uniquely human concepts when it comes to zoology. Welcome to the brave new world. You happen to be alive in it. But who else is listening? Increasingly, we shall get to decide. Bye-bye, or hello: you and I get to choose.
• Jules Howard is a zoologist and the author of Sex on Earth, and Death on Earth
High-pitched, eerie and yet distinct, the sound of a voice calling the name “Amy” is unmistakable. But this isn’t a human cry – it’s the voice of a killer whale called Wikie.
New research reveals that orcas are able to imitate human speech, in some cases at the first attempt, saying words such as “hello”, “one, two” and “bye bye”.
The study also shows that the creatures are able to copy unfamiliar sounds produced by other orcas – including a sound similar to blowing a raspberry.
Scientists say the discovery helps to shed light on how different pods of wild killer whales have ended up with distinct dialects, adding weight to the idea that they are the result of imitation between orcas. The creatures are already known for their ability to copy the movements of other orcas, with some reports suggesting they can also mimic the sounds of bottlenose dolphins and sea lions.
“We wanted to see how flexible a killer whale can be in copying sounds,” said Josep Call, professor in evolutionary origins of mind at the University of St Andrews and a co-author of the study. “We thought what would be really convincing is to present them with something that is not in their repertoire – and in this case ‘hello’ [is] not what a killer whale would say.”
Wikie is not the first animal to have managed the feat of producing human sounds: dolphins, elephants, parrots, orangutans and even beluga whales have all been captured mimicking our utterances, although they use a range of physical mechanisms to us to do so. Noc, the beluga whale, made novel use of his nasal cavities, while Koshik, an Indian elephant jammed his trunk in his mouth, resulting in the pronouncement of Korean words ranging from “hello” to “sit down” and “no”.
But researchers say only a fraction of the animal kingdom can mimic human speech, with brain pathways and vocal apparatus both thought to determine whether it is possible.
“That is what makes it even more impressive – even though the morphology [of orcas] is so different, they can still produce a sound that comes close to what another species, in this case us, can produce,” said Call.
He poured cold water, however, on the idea that orcas might understand the words they mimic. “We have no evidence that they understand what their ‘hello’ stands for,” he said.
Writing in the journal Proceedings of the Royal Society B: Biological Sciences, researchers from institutions in Germany, UK, Spain and Chile, describe how they carried out the latest research with Wikie, a 14-year-old female orca living in an aquarium in France. She had previously been trained to copy actions performed by another orca when given a human gesture.
After first brushing up Wikie’s grasp of the “copy” command, she was trained to parrot three familiar orca sounds made by her three-year old calf Moana.
Wikie was then additionally exposed to five orca sounds she had never heard before, including noises resembling a creaking door and the blowing a raspberry.
Finally, Wikie was exposed to a human making three of the orca sounds, as well as six human sounds, including “hello”, “Amy”, “ah ha”, “one, two” and “bye bye”.
“You cannot pick a word that is very complicated because then I think you are asking too much – we wanted things that were short but were also distinctive,” said Call.
Throughout the study, Wikie’s success was first judged by her two trainers and then confirmed from recordings by six independent adjudicators who compared them to the original sound, without knowing which was which.
The team found that Wikie was often quickly able to copy the sounds, whether from an orca or a human, with all of the novel noises mimicked within 17 trials. What’s more, two human utterances and all of the human-produced orca sounds were managed on the first attempt – although only one human sound – “hello” – was correctly produced more than 50% of the time on subsequent trials.
The matching was further backed up through an analysis of various acoustic features from the recordings of Wikie’s sounds.
While the sounds were all made and copied when the animals’ heads were out of the water, Call said the study shed light on orca behaviour.
“I think here we have the first evidence that killer whales may be learning sounds by vocal imitation, and this is something that could be the basis of the dialects we observe in the wild – it is plausible,” said Call, noting that to further test the idea, trials would have to be carried out with wild orcas.
Diana Reiss, an expert in dolphin communication and professor of psychology at Hunter College, City University of New York, welcomed the research, noting that it extends our understanding of orcas’ vocal abilities, with Wikie able to apply a “copy” command learned for imitation of actions to imitation of sounds.
Dr Irene Pepperberg, an expert in parrot cognition at Harvard University, also described the study as exciting, but said: “A stronger test would have been whether the various sounds produced could be correctly classified by humans without the models present for comparison.”
Transmissão de práticas de uso de ferramentas por macacos-prego ajuda a repensar o papel das tradições na evolução
Com uma pedra erguida acima da cabeça, o jovem Porthos bate vigorosamente no chão arenoso de modo a abrir um buraco. Seu objetivo: uma aranha, que logo consegue desentocar e rola entre as mãos para tontear a presa que em seguida come. Ele é um macaco-prego da espécie Sapajus libidinosus, habitante do Parque Nacional Serra da Capivara, no Piauí, e objeto de estudo de pesquisadores do Instituto de Psicologia da Universidade de São Paulo (IP-USP). O biólogo Tiago Falótico tem caracterizado o uso de ferramentas por esses animais (ver Pesquisa FAPESP nº 196) e mostrou, em artigo publicado em julho na revista Scientific Reports, que a ação do jovem macho envolve conhecimento, aprendizado e transmissão de práticas culturais – ou tradições, como alguns preferem chamar quando os sujeitos não são humanos – dentro de grupos sociais. A pesquisa está no bojo de um corpo teórico que busca entrelaçar biologia, ciências sociais e humanas e recém-desembocou na formação da Sociedade de Evolução Cultural. Sua reunião inaugural acaba de acontecer na Alemanha, entre 13 e 15 de setembro.
Até agora, o uso de pedras como ferramentas para cavar só foi documentado nessa população. Especialmente quando se trata de desentocar aranhas, é preciso experiência. O estudo, resultado de observações feitas durante o doutorado de Falótico, encerrado em 2011 sob orientação do biólogo Eduardo Ottoni, mostra que quase 60% dos adultos e jovens (como Porthos) têm sucesso na tarefa. Macacos juvenis (o correspondente a crianças), por outro lado, só conseguem em pouco mais de 30% dos casos. Isso acontece porque é preciso reconhecer o revestimento de seda que fecha a toca do aracnídeo, sinal de que o habitante está lá dentro. “Os juvenis às vezes cavam uma toca que acabou de ser aberta por outro macaco”, conta Falótico. Estruturas subterrâneas, parecidas com batatas, da planta conhecida como farinha-seca (Thiloa glaucocarpa), também são desenterradas com mais eficiência pelos adultos. Já as raízes de louro (Ocotea), outro alimento desses primatas, apesar de envolverem o uso de pedras maiores, não parecem apresentar um desafio especial para os aprendizes. Macacos dos dois sexos se mostraram igualmente capazes de cavar com pedras, com uma taxa de sucesso equivalente, embora eles pareçam ter mais interesse pela atividade: entre as 1.702 situações observadas, 77% envolviam machos e apenas 23%, fêmeas.
“Esperávamos encontrar uma correlação entre o uso de ferramentas e a escassez de alimentos, mas não foi o que vimos”, conta Falótico. Se os macacos da serra da Capivara encontram algo comestível que exija o uso de ferramentas, recorrem a elas. Seu modo de vida, em que passam metade do tempo no chão rodeados de pedras e gravetos, parece ser propício ao desenvolvimento das habilidades. Mas não é só isso. Embora não haja diferença entre os sexos nos hábitos alimentares, as fêmeas nunca usam gravetos – que seus companheiros masculinos utilizam para desentocar lagartos de frestas e retirar insetos de troncos, por exemplo. Há diferença apenas, aparentemente, no interesse. “Quando um macho vê outro usar uma vareta, ele observa atento; já uma fêmea, mesmo que esteja ao lado daquele usando a ferramenta, não se interessa e olha para o outro lado!”
Os macacos da mesma espécie que habitam a fazenda Boa Vista, em Gilbués, cerca de 300 quilômetros (km) para sudoeste, têm tradições distintas no uso de ferramentas. Ali, uma área com mais influência de Cerrado do que Caatinga, as pedras são menos abundantes, mas necessárias (e usadas) para quebrar cocos. Gravetos estão por toda parte, mas não têm uso. Essa diferença cultural entre grupos de macacos foi explorada em um experimento feito pelo psicólogo Raphael Moura Cardoso durante o doutorado, orientado por Eduardo Ottoni, e relatado em artigo de 2016 na Biology Letters. Eles puseram – tanto na fazenda Boa Vista como na serra da Capivara – caixas de acrílico recheadas de melado de cana. O único jeito de retirar a guloseima era por meio de uma fenda no alto com largura suficiente apenas para varetas. “Na serra da Capivara, um macho logo acertou uma pedrada na caixa”, lembra Ottoni, que, previdente, tinha planejado o aparato “à prova de macaco-prego”. “Quando nada aconteceu, ele largou a pedra, coçou a cabeça e pegou um graveto.” Ele brinca que nem precisou editar o vídeo para mostrar em um congresso – foi uma ação contínua e imediata. Ao longo de cinco dias de exposição à caixa, 10 dos 14 machos usaram o graveto logo na primeira sessão, e apenas os três mais jovens não foram bem-sucedidos. Os demais conseguiram um sucesso de 90% na empreitada. As fêmeas não tentaram, assim como os macacos da fazenda Boa Vista. Lá, os pesquisadores até tentaram ajudar: depois de seis horas expostos à tarefa, os macacos deparavam com um graveto já fincado na fenda. Mesmo tirando e lambendo o melado da ponta, nenhum deles voltou a inserir a ferramenta na caixa ao longo de 13 dias de experimento. Uma surpresa foi que os macacos da Boa Vista, exímios quebradores de coco, não tentaram partir a caixa. “Eu esperava isso deles, não dos outros”, diz Ottoni.
Os resultados, surpreendentes, podem reforçar a importância da transmissão de tradições entre os macacos. A capa da edição de 25 de julho deste ano da revista PNAS traz justamente a foto de um macaco-prego da fazenda Boa Vista comendo uma castanha que conseguiu quebrar com a ajuda de uma grande pedra redonda, observado de perto por um jovem. A imagem anuncia a coletânea especial sobre como a cultura se conecta à biologia, da qual faz parte um artigo do grupo liderado pelas primatólogas Patrícia Izar, do IP-USP, Dorothy Fragaszy, da Universidade da Georgia, nos Estados Unidos, e Elisabetta Visalberghi, do Instituto de Ciências e Tecnologias Cognitivas, na Itália, sobre os macacos da fazenda Boa Vista, que estudam sistematicamente desde 2006. Nas observações recolhidas ao longo desse tempo, chama a atenção a tolerância dos adultos em relação aos jovens aprendizes que olham de perto e até comem pedaços dos cocos partidos. “Os adultos competem pelos recursos e os imaturos podem ficar perto”, conta Patrícia. As análises publicadas no artigo recente mostram muito mais do que proximidade: os quebradores de coco influenciam a atividade dos outros, sobretudo os jovens, que também começam a manipular pedras e cocos. Isso dura alguns minutos. “A tradição canaliza a atividade para o mesmo tipo de ação importante para essa tradição”, define.
Patrícia ressalta que os macacos nascem nesse contexto. “Muitas vezes vemos filhotes nas costas das mães enquanto elas quebram”, conta. Com esse aprendizado contínuo, acabam se tornando especialistas na tarefa. Mas não basta observar, e daí a importância de os filhotes serem atraídos pela ação dos adultos – principalmente os mais eficazes. “O sucesso passa pela percepção da tarefa e das propriedades da ferramenta”, detalha, descrevendo um complexo corpo-ferramenta em que é constantemente necessário ajustar força, gestos e postura. Quando quebram tucum, um coquinho menos resistente, os macacos ajustam a força das pancadas depois de ouvirem o som da superfície rachando, o grupo mostrou em artigo do ano passado na Animal Behaviour. Para cocos mais difíceis, eles escolhem pedras que podem chegar a ser mais pesadas do que o próprio corpo. E a seleção da pedra é criteriosa, conforme mostrou um experimento em que Patrícia e seu grupo forneceram pedras artificiais com diferentes tamanhos, pesos e densidades. As pedras grandes logo atraíam a atenção dos macacos, mas se fossem pouco densas – mais leves do que aparentavam – eram abandonadas. “Eles têm a percepção de que o peso é importante na quebra”, diz Patrícia.
Tolerância: macho adulto da fazenda Boa Vista come castanha partida observado de perto por jovem
Essas sociedades primatas alteram o ambiente. Macacos escolhem pedras ou troncos achatados como base para quebrar coco, e para lá carregam as raras pedras grandes e duras que encontram no ambiente. Essa conformação é importante não só por criar oficinas de quebra, mas por canalizar a possibilidade de aprendizado, já que todos sabem onde a atividade acontece e pode ser observada. “Não faz sentido pensar em maturação motora independente do contexto social, alimentar”, afirma a bióloga Briseida Resende, também do IP-USP e coautora do artigo da PNAS. O desenvolvimento individual depende das experiências de cada um, de suas capacidades físicas e do acervo acumulado pelo grupo, no qual uma inovação criada pode se disseminar, perpetuar-se e fazer parte da cultura mantida por gerações. Resende defende que indivíduo e sociedade são indissociáveis, embora historicamente tenham sido vistos como entidades distintas.
Reunir a evolução cultural e a biológica é justamente o foco da síntese estendida, agora sedimentada com a fundação, em 2016, da Sociedade de Evolução Cultural – o primeiro presidente é o zoólogo Peter Richerson, da Universidade da Califórnia em Davis, cujo grupo privilegia a estatística. Essa visão conjunta amplia o olhar evolutivo, já que a transmissão de ideias ou inovações não se dá apenas de pais para filhos e pode trazer vantagens seletivas favorecendo as capacidades cognitivas e sociais relevantes. Considera também que a cultura pode influenciar aspectos físicos, como a conformação e o tamanho do cérebro, ou o desenvolvimento de habilidades que por sua vez sedimentam o comportamento. Os genes e a cultura, duas vias de transmissão de informação, relacionam-se, portanto, por uma via de mão dupla.
Jovens aprendizes tentam tirar proveito de escavação feita por fêmea
A oportunidade de ver comportamentos surgirem e se espalhar é rara, e por isso abordagens experimentais que provocam inovações são um acréscimo importante aos comportamentos diversos dos macacos-prego do Piauí. Ferramentas estatísticas recentes podem ajudar a aprofundar essa compreensão, como a Análise de Difusão Baseada em Redes (Network-Based Diffusion Analysis) que o grupo de Ottoni começa a usar. “O programa monta uma rede social aleatória e compara à real”, explica o pesquisador, que torna as análises mais robustas inserindo características medidas nos sujeitos em causa. Em agosto de 2016 ele apresentou, no congresso da Sociedade Primatológica Internacional, em Chicago, resultados do experimento feito pela bióloga Camila Coelho durante doutorado orientado por ele com um período passado na Universidade de Durham, no Reino Unido, para aprender o método. Os resultados indicam que, no caso dos macacos-prego, o aprendizado social prevê a difusão de informação na espécie.
Até meio século atrás, o uso de ferramentas era considerado privilégio humano. Ao observar chimpanzés na Tanzânia, a inglesa Jane Goodall derrubou essa exclusividade e, de certa maneira, causou a redefinição das fronteiras entre gente e bicho. Muito se descobriu de lá para cá, mas falar em cultura animal ainda esbarra em certo desconforto. Talvez não por muito mais tempo.
O uso de pedras para escavar só foi descrito na serra da Capivara
Sob o comando de hormônios
O cuidado com os filhotes está ligado ao hormônio oxitocina em mamíferos. O grupo liderado por Maria Cátira Bortolini, da Universidade Federal do Rio Grande do Sul, descreveu há poucos anos as variações na molécula de oxitocina em espécies de macacos nas quais há bons pais (ver Pesquisa FAPESP nº 228). Ensaios farmacológicos feitos no laboratório do bioquímico Claudio Costa-Neto, da Faculdade de Medicina de Ribeirão Preto da USP, agora desvendaram o caminho da oxitocina dentro das células e verificaram que os receptores das formas alteradas ficam mais expostos nas membranas das células, de maneira que o sistema não se dessensibiliza. “É como se o macaco recebesse constantemente a instrução ‘tenho que cuidar dos filhotes’”, explica Cátira. Faz diferença para a sobrevivência de saguis, que frequentemente têm filhotes gêmeos, por exemplo.
O resultado está em artigo publicado em agosto na PNAS, que também descreve o resultado da aplicação dessas oxitocinas em ratos por meio de borrifadas nasais, experimento realizado em colaboração com o fisiologista Aldo Lucion, da UFRGS. As fêmeas lactantes, já inundadas de oxitocina, alteraram pouco o comportamento. Mas os machos tratados com o hormônio alteraram radicalmente o hábito de ignorar os filhotes e correram para cheirá-los, uma reação que foi três vezes mais rápida com a oxitocina de sagui.
Os cebídeos, família que inclui os macacos-prego, também têm um tipo de oxitocina que aumenta a propensão à paternidade ativa. Os grupos de Cátira e de Ottoni recentemente iniciaram uma colaboração para investigar as características genéticas em machos mais e menos cuidadores. “Já conseguimos extrair material genético de amostras de fezes e estamos selecionando genes candidatos a serem rastreados”, conta ela, fascinada com a tolerância dos machos e as habilidades cognitivas dos primatas do Piauí. “A capacidade de inovar, por um lado, e a de sentar e observar, por outro, são necessárias para o desenvolvimento e a transmissão de traços culturais adaptativos e certamente há um cenário genético por trás disso.”
3. Desenvolvimento de novos ligantes/drogas com ação agonística seletiva (biased agonism) para receptores dos sistemas renina-angiotensina e calicreínas-cininas: Novas propriedades e novas aplicações biotecnológicas (nº 12/20148-0); ModalidadeProjeto Temático; Pesquisador responsável Claudio Miguel da Costa Neto (USP); Investimento R$ 3.169.674,21.
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June 2, 2016
The first domesticated animals may have been tamed twice.
Tens of thousands of years ago, before the internet, before the Industrial Revolution, before literature and mathematics, bronze and iron, before the advent of agriculture, early humans formed an unlikely partnership with another animal—the grey wolf. The fates of our two species became braided together. The wolves changed in body and temperament. Their skulls, teeth, and paws shrank. Their ears flopped. They gained a docile disposition, becoming both less frightening and less fearful. They learned to read the complex expressions that ripple across human faces. They turned into dogs.
Today, dogs are such familiar parts of our lives—our reputed best friends and subject of many a meme—that it’s easy to take them, and what they represent, for granted. Dogs were the first domesticated animals, and their barks heralded the Anthropocene. We raised puppies well before we raised kittens or chickens; before we herded cows, goats, pigs, and sheep; before we planted rice, wheat, barley, and corn; before we remade the world.
“Remove domestication from the human species, and there’s probably a couple of million of us on the planet, max,” says archaeologist and geneticist Greger Larson. “Instead, what do we have? Seven billion people, climate change, travel, innovation and everything. Domestication has influenced the entire earth. And dogs were the first.” For most of human history, “we’re not dissimilar to any other wild primate. We’re manipulating our environments, but not on a scale bigger than, say, a herd of African elephants. And then, we go into partnership with this group of wolves. They altered our relationship with the natural world.”
Larson wants to pin down their origins. He wants to know when, where, and how they were domesticated from wolves. But after decades of dogged effort, he and his fellow scientists are still arguing about the answers. They agree that all dogs, from low-slung corgis to towering mastiffs, are the tame descendants of wild ancestral wolves. But everything else is up for grabs.
Some say wolves were domesticated around 10,000 years ago, while others say 30,000. Some claim it happened in Europe, others in the Middle East, or East Asia. Some think early human hunter-gatherers actively tamed and bred wolves. Others say wolves domesticated themselves, by scavenging the carcasses left by human hunters, or loitering around campfires, growing tamer with each generation until they became permanent companions.
Dogs were domesticated so long ago, and have cross-bred so often with wolves and each other, that their genes are like “a completely homogenous bowl of soup,” Larson tells me, in his office at the University of Oxford. “Somebody goes: what ingredients were added, in what proportion and in what order, to make that soup?” He shrugs his shoulders. “The patterns we see could have been created by 17 different narrative scenarios, and we have no way of discriminating between them.”
The only way of doing so is to look into the past. Larson, who is fast-talking, eminently likable, and grounded in both archaeology and genetics, has been gathering fossils and collaborators in an attempt to yank the DNA out of as many dog and wolf fossils as he can. Those sequences will show exactly how the ancient canines relate to each other and to modern pooches. They’re the field’s best hope for getting firm answers to questions that have hounded them for decades.
And already, they have yielded a surprising discovery that could radically reframe the debate around dog domestication, so that the big question is no longer when it happened, or where, but how many times.
* * *
On the eastern edge of Ireland lies Newgrange, a 4,800-year-old monument that predates Stonehenge and the pyramids of Giza. Beneath its large circular mound and within its underground chambers lie many fragments of animal bones. And among those fragments, Dan Bradley from Trinity College Dublin found the petrous bone of a dog.
Press your finger behind your ear. That’s the petrous. It’s a bulbous knob of very dense bone that’s exceptionally good at preserving DNA. If you try to pull DNA out of a fossil, most of it will come from contaminating microbes and just a few percent will come from the bone’s actual owner. But if you’ve got a petrous bone, that proportion can be as high as 80 percent. And indeed, Bradley found DNA galore within the bone, enough to sequence the full genome of the long-dead dog.
Larson and his colleague Laurent Frantz then compared the Newgrange sequences with those of almost 700 modern dogs, and built a family tree that revealed the relationships between these individuals. To their surprise, that tree had an obvious fork in its trunk—a deep divide between two doggie dynasties. One includes all the dogs from eastern Eurasia, such as Shar Peis and Tibetan mastiffs. The other includes all the western Eurasian breeds, and the Newgrange dog.
The genomes of the dogs from the western branch suggest that they went through a population bottleneck—a dramatic dwindling of numbers. Larson interprets this as evidence of a long migration. He thinks that the two dog lineages began as a single population in the east, before one branch broke off and headed west. This supports the idea that dogs were domesticated somewhere in China.
But there’s a critical twist.
The team calculated that the two dog dynasties split from each other between 6,400 and 14,000 years ago. But the oldest dog fossils in both western and eastern Eurasia are older than that. Which means that when those eastern dogs migrated west into Europe, there were already dogs there.
Here’s the full story, as he sees it. Many thousands of years ago, somewhere in western Eurasia, humans domesticated grey wolves. The same thing happened independently, far away in the east. So, at this time, there were two distinct and geographically separated groups of dogs. Let’s call them Ancient Western and Ancient Eastern. Around the Bronze Age, some of the Ancient Eastern dogs migrated westward alongside their human partners, separating from their homebound peers and creating the deep split in Larson’s tree. Along their travels, these migrants encountered the indigenous Ancient Western dogs, mated with them (doggy style, presumably), and effectively replaced them.
Today’s eastern dogs are the descendants of the Ancient Eastern ones. But today’s western dogs (and the Newgrange one) trace most of their ancestry to the Ancient Eastern migrants. Less than 10 percent comes from the Ancient Western dogs, which have since gone extinct.
This is a bold story for Larson to endorse, not least because he himself has come down hard on other papers suggesting that cows, sheep, or other species were domesticated twice. “Any claims for more than one need to be substantially backed up by a lot of evidence,” he says. “Pigs were clearly domesticated in Anatolia and in East Asia. Everything else is once.” Well, except maybe dogs.
* * *
Other canine genetics experts think that Larson’s barking up the wrong tree. “I’m somewhat underwhelmed, since it’s based on a single specimen,” says Bob Wayne from the University of California, Los Angeles. He buys that there’s a deep genetic division between modern dogs. But, it’s still possible that dogs were domesticated just once, creating a large, widespread, interbreeding population that only later resolved into two distinct lineages.
In 2013, Wayne’s team compared the mitochondrial genomes (small rings of DNA that sit outside the main set) of 126 modern dogs and wolves, and 18 fossils. They concluded that dogs were domesticated somewhere in Europe or western Siberia, between 18,800 and 32,100 years ago. And genes aside, “the density of fossils from Europe tells us something,” says Wayne. “There are many things that look like dogs, and nothing quite like that in east Asia.”
Peter Savolainen from the KTH Royal Institute of Technology in Stockholm disagrees. By comparing the full genomes of 58 modern wolves and dogs, his team has shown that dogs in southern China are the most genetically diverse in the world. They must have originated there around 33,000 years ago, he says, before a subset of them migrated west 18,000 years later.
That’s essentially the same story that Larson is telling. The key difference is that Savolainen doesn’t buy the existence of an independently domesticated group of western dogs. “That’s stretching the data very much,” he says. Those Ancient Western dogs might have just been wolves, he says. Or perhaps they were an even earlier group of migrants from the east. “I think the picture must seem a bit chaotic,” he says understatedly. “But for me, it’s pretty clear. It must have happened in southern East Asia. You can’t interpret it any other way.”
Except, you totally can. Wayne does (“I’m certainly less dogmatic than Peter,” he says). Adam Boyko from Cornell University does, too: after studying the genes of village dogs—free-ranging mutts that live near human settlements—he argued for a single domestication in Central Asia, somewhere near India or Nepal. And clearly, Larson does as well.
Larson adds that his gene-focused peers are ignoring one crucial line of evidence—bones. If dogs originated just once, there should be a neat gradient of fossils with the oldest ones at the center of domestication and the youngest ones far away from it. That’s not what we have. Instead, archaeologists have found 15,000-year-old dog fossils in western Europe, 12,500-year-old ones in east Asia, and nothing older than 8,000 years in between.
“If we’re wrong, then how on earth do you explain the archaeological data?” says Larson. “Did dogs jump from East Asia to Western Europe in a week, and then go all the way back 4,000 years later?” No. A dual domestication makes more sense. Mietje Genompré, an archaeologist from the Royal Belgian Institute of Natural Sciences, agrees that the bones support Larson’s idea. “For me, it’s very convincing,” she says.
But even Larson is hedging his bets. When I ask him how strong his evidence is, he says, “Like, put a number on it? If was being bold, I’d say it’s a 7 out of 10. We lack the smoking gun.”
Why is this is so hard? Of all the problems that scientists struggle with, why has the origin of dogs been such a bitch to solve?
For starters, the timing is hard to pin down because no one knows exactly how fast dog genomes change. That pace—the mutation rate—underpins a lot of genetic studies. It allows scientists to compare modern dogs and ask: How long ago must these lineages have diverged in order to build up this many differences in their genes? And since individual teams use mutation rate estimates that are wildly different, it’s no wonder they’ve arrive at conflicting answers.
Regardless of the exact date, it’s clear that over thousands of years, dogs have mated with each other, cross-bred with wolves, travelled over the world, and been deliberately bred by humans. The resulting ebb and flow of genes has turned their history into a muddy, turbid mess—the homogeneous soup that Larson envisages.
Wolves provide no clarity. Grey wolves used to live across the entire Northern Hemisphere, so they could have potentially been domesticated anywhere within that vast range (although North America is certainly out). What’s more, genetic studies tell us that no living group of wolves is more closely related to dogs than any other, which means that the wolves that originally gave rise to dogs are now extinct. Sequencing living wolves and dogs will never truly reveal their shrouded past; it’d be, as Larson says, like trying to solve a crime when the culprit isn’t even on the list of suspects.
“The only way to know for sure is to go back in time,” he adds.
* * *
The study informally known as the Big Dog Project was born of frustration. Back in 2011, Larson was working hard on the origin of domestic pigs, and became annoyed that scientists studying dogs were getting less rigorous papers in more prestigious journals, simply because their subjects were that much more charismatic and media-friendly. So he called up his longstanding collaborator Keith Dobney. “Through gritted teeth, I said: We’re fucking doing dogs. And he said: I’m in.”
Right from the start, the duo realized that studying living dogs would never settle the great domestication debate. The only way to do that was to sequence ancient DNA from fossil dogs and wolves, throughout their range and at different points in history. While other scientists were studying the soup of dog genetics by tasting the finished product, Larson would reach back in time to taste it at every step of its creation, allowing him to definitively reconstruct the entire recipe.
In recent decades, scientists have become increasingly successful at extracting and sequencing strands of DNA from fossils. This ancient DNA has done wonders for our understanding of our own evolution. It showed, for example, how Europe was colonized 40,000 years ago by hunter-gatherers moving up from Africa, then 8,000 years ago by Middle Eastern farmers, and 5,000 years ago by horse-riding herders from the Russian steppes. “Everyone in Europe today is a blend of those three populations,” says Larson, who hopes to parse the dog genome in the same way, by slicing it into its constituent ingredients.
Larson originally envisaged a small project—just him and Dobney analyzing a few fossils. But he got more funding, collaborators, and samples than he expected. “It just kind of metastasized out of all proportion,” he says. He and his colleagues would travel the world, drilling into fossils and carting chips of bone back to Oxford. They went to museums and private collections. (“There was a guy up in York who had a ton of stuff in his garage.”) They grabbed bones from archaeological sites.
The pieces of bone come back to a facility in Oxford called the Palaeo-BARN—the Palaeogenomics and Bioarchaeology Research Network. When I toured the facility with Larson, we wore white overalls, surgical masks, oversoles, and purple gloves, to keep our DNA (and that of our skin microbes) away from the precious fossil samples. Larson called them ‘spacesuits.’ I was thinking ‘thrift-store ninja.’
In one room, the team shoves pieces of bone into a machine that pounds it with a small ball bearing, turning solid shards into fine powder. They then send the powder through a gauntlet of chemicals and filters to pull out the DNA and get rid of everything else. The result is a tiny drop of liquid that contains the genetic essence of a long-dead dog or wolf. Larson’s freezer contains 1,500 such drops, and many more are on the way. “It’s truly fantastic the kind of data that he has gathered,” says Savolainen.
True to his roots in archaeology, Larson isn’t ignoring the bones. His team photographed the skulls of some 7,000 prehistoric dogs and wolves at 220 angles each, and rebuilt them in virtual space. They can use a technique called geometric morphometrics to see how different features on the skulls have evolved over time.
The two lines of evidence—DNA and bones—should either support or refute the double domestication idea. It will also help to clear some confusion over a few peculiar fossils, such as a 36,000 year old skull from Goyet cave in Belgium. Genompré thinks it’s a primitive dog. “It falls outside the variability of wolves: it’s smaller and the snout is different,” she says. Others say it’s too dissimilar to modern dogs. Wayne has suggested that it represents an aborted attempt at domestication—a line of dogs that didn’t contribute to modern populations and is now extinct.
Maybe the Goyet hound was part of Larson’s hypothetical Ancient Western group, domesticated shortly after modern humans arrived in Europe. Maybe it represented yet another separate flirtation with domestication. All of these options are on the table, and Larson thinks he has the data to tell them apart. “We can start putting numbers on the difference between dogs and wolves,” he says. “We can say this is what all the wolves at this time period look like; does the Goyet material fall within that realm, or does it look like dogs from later on?”
Larson hopes to have the first big answers within six to twelve months. “I think it’ll clearly show that some things can’t be right, and will narrow down the number of hypotheses,” says Boyko. “It may narrow it down to one but I’m not holding my breath on that.” Wayne is more optimistic. “Ancient DNA will provide much more definitive data than we had in the past,” he says. “[Larson] convinced everyone of that. He’s a great diplomat.”
Indeed, beyond accumulating DNA and virtual skulls, Larson’s greatest skill is in gathering collaborators. In 2013, he rounded up as many dog researchers as he could and flew them to Aberdeen, so he could get them talking. “I won’t say there was no tension,” he says. “You go into a room with someone who has written something that sort of implies you aren’t doing very good science… there will be tension. But it went away very quickly. And, frankly: alcohol.”
“Everyone was like: You know what? If I’m completely wrong and I have to eat crow on this, I don’t give a shit. I just want to know.”
- April 27, 2016
- For the first time, scientists have demonstrated that an organism devoid of a nervous system is capable of learning. Biologists have succeeded in showing that a single-celled organism, the protist, is capable of a type of learning called habituation. This discovery throws light on the origins of learning ability during evolution, even before the appearance of a nervous system and brain. It may also raise questions as to the learning capacities of other extremely simple organisms such as viruses and bacteria.
For the first time, scientists have demonstrated that an organism devoid of a nervous system is capable of learning. A team from the Centre de Recherches sur la Cognition Animale (CNRS/Université Toulouse III — Paul Sabatier) has succeeded in showing that a single-celled organism, the protist Physarum polycephalum, is capable of a type of learning called habituation. This discovery throws light on the origins of learning ability during evolution, even before the appearance of a nervous system and brain. It may also raise questions as to the learning capacities of other extremely simple organisms such as viruses and bacteria. These findings are published in the Proceedings of the Royal Society B on 27 April 2016.
An ability to learn, and memory are key elements in the animal world. Learning from experiences and adapting behavior accordingly are vital for an animal living in a fluctuating and potentially dangerous environment. This faculty is generally considered to be the prerogative of organisms endowed with a brain and nervous system. However, single-celled organisms also need to adapt to change. Do they display an ability to learn? Bacteria certainly show adaptability, but it takes several generations to develop and is more a result of evolution. A team of biologists thus sought to find proof that a single-celled organism could learn. They chose to study the protist, or slime mold, Physarum polycephalum, a giant cell that inhabits shady, cool areas and has proved to be endowed with some astonishing abilities, such as solving a maze, avoiding traps or optimizing its nutrition. But until now very little was known about its ability to learn.
During a nine-day experiment, the scientists thus challenged different groups of this mold with bitter but harmless substances that they needed to pass through in order to reach a food source. Two groups were confronted either by a “bridge” impregnated with quinine, or with caffeine, while the control group only needed to cross a non-impregnated bridge. Initially reluctant to travel through the bitter substances, the molds gradually realized that they were harmless, and crossed them increasingly rapidly — behaving after six days in the same way as the control group. The cell thus learned not to fear a harmless substance after being confronted with it on several occasions, a phenomenon that the scientists refer to as habituation. After two days without contact with the bitter substance, the mold returned to its initial behavior of distrust. Furthermore, a protist habituated to caffeine displayed distrustful behavior towards quinine, and vice versa. Habituation was therefore clearly specific to a given substance.
Habituation is a form of rudimentary learning, which has been characterized in Aplysia (an invertebrate also called sea hare). This form of learning exists in all animals, but had never previously been observed in a non-neural organism. This discovery in a slime mold, a distant cousin of plants, fungi and animals that appeared on Earth some 500 million years before humans, improves existing understanding of the origins of learning, which markedly preceded those of nervous systems. It also offers an opportunity to study learning types in other very simple organisms, such as viruses or bacteria.
 This single cell, which contains thousands of nuclei, can cover an area of around a square meter and moves within its environment at speeds that can reach 5 cm per hour.
 See “Even single-celled organisms feed themselves in a ‘smart’ manner.” https://www.sciencedaily.com/releases/2010/02/100210164712.htm
 Mild tactile stimulation of the animal’s siphon normally causes the defensive reflex of withdrawing the branchiae. If the harmless tactile stimulation is repeated, this reflex diminishes and finally disappears, thus indicating habituation.
- Romain P. Boisseau, David Vogel, Audrey Dussutour. Habituation in non-neural organisms: evidence from slime moulds. Proceedings of the Royal Society B: Biological Sciences, 2016; 283 (1829): 20160446 DOI: 10.1098/rspb.2016.0446
Laughter? Now wait a minute! A real scientist should avoid any and all anthropomorphism, which is why hard-nosed colleagues often ask us to change our terminology. Why not call the ape’s reaction something neutral, like, say, vocalized panting? That way we avoid confusion between the human and the animal.
The term anthropomorphism, which means “human form,” comes from the Greek philosopher Xenophanes, who protested in the fifth century B.C. against Homer’s poetry because it described the gods as though they looked human. Xenophanes mocked this assumption, reportedly saying that if horses had hands they would “draw their gods like horses.” Nowadays the term has a broader meaning. It is typically used to censure the attribution of humanlike traits and experiences to other species. Animals don’t have “sex,” but engage in breeding behavior. They don’t have “friends,” but favorite affiliation partners.
Given how partial our species is to intellectual distinctions, we apply such linguistic castrations even more vigorously in the cognitive domain. By explaining the smartness of animals either as a product of instinct or simple learning, we have kept human cognition on its pedestal under the guise of being scientific. Everything boiled down to genes and reinforcement. To think otherwise opened you up to ridicule, which is what happened to Wolfgang Köhler, the German psychologist who, a century ago, was the first to demonstrate flashes of insight in chimpanzees.
Köhler would put a banana outside the enclosure of his star performer, Sultan, while giving him sticks that were too short to reach the fruit through the bars. Or he would hang a banana high up and spread boxes around, none of which were tall enough to reach the fruit. At first, Sultan would jump or throw things at the banana or drag a human by the hand toward it, hoping to use him as a footstool. If this failed, he would sit around without doing anything, pondering the situation, until he might hit on a solution. He’d jump up suddenly to put one bamboo stick inside another, making a longer stick. He’d also stack boxes to build a tower tall enough to attain his reward. Köhler described this moment as the “aha! experience,” not unlike Archimedes running through the streets shouting “Eureka!”
According to Köhler, Sultan showed insight by combining what he knew about boxes and sticks to produce a brand-new action sequence to take care of his problem. It all took place in his head, without prior rewards for his eventual solution. That animals may show mental processes closer to thinking than learning was so unsettling, though, that still today Köhler’s name is hissed rather than spoken in some circles. Naturally, one of his critics argued that the attribution of reasoning to animals was an “overswing of the theoretical pendulum” back “toward anthropomorphism.”
We still hear this argument, not so much for tendencies that we consider animalistic (everyone is free to speak of aggression, violence and territoriality in animals) but rather for traits that we like in ourselves. Accusations of anthropomorphism are about as big a spoiler in cognitive science as suggestions of doping are of athletic success. The indiscriminate nature of these accusations has been detrimental to cognitive science, as it has kept us from developing a truly evolutionary view. In our haste to argue that animals are not people, we have forgotten that people are animals, too.
This doesn’t mean that anything goes. Humans are incredibly eager to project feelings and experiences onto animals, often doing so uncritically. We go to beach hotels to swim with dolphins, convinced that the animals must love it as much as we do. We think that our dog feels guilt or that our cat is embarrassed when she misses a jump. Lately, people have fallen for the suggestion that Koko, the signing gorilla in California, is worried about climate change, or that chimpanzees have religion. As soon as I hear such claims, I contract my corrugator muscles (causing a frown) and ask for the evidence. Yes, dolphins have smiley faces, but since this is an immutable part of their visage, it fails to tell us anything about how they feel. Yes, dogs hide under the table when they have done something wrong, yet the most likely explanation is that they fear trouble.
Gratuitous anthropomorphism is distinctly unhelpful. However, when experienced field workers who follow apes around in the tropical forest tell me about the concern chimpanzees show for an injured companion, bringing her food or slowing down their walking pace, or report how adult male orangutans in the treetops vocally announce which way they expect to travel the next morning, I am not averse to speculations about empathy or planning. Given everything we know from controlled experiments in captivity, such as the ones I conduct myself, these speculations are not far-fetched.
To understand the resistance to cognitive explanations, I need to mention a third ancient Greek: Aristotle. The great philosopher put all living creatures on a vertical Scala Naturae, which runs from humans (closest to the gods) down toward other mammals, with birds, fish, insects and mollusks near the bottom. Comparisons up and down this vast ladder have been a popular scientific pastime, but all we have learned from them is how to measure other species by our standards. Keeping Aristotle’s scale intact, with humans on top, has been the unfailing goal.
But think about it: How likely is it that the immense richness of nature fits on a single dimension? Isn’t it more likely that each animal has its own cognition, adapted to its own senses and natural history? It makes no sense to compare our cognition with one that is distributed over eight independently moving arms, each with its own neural supply, or one that enables a flying organism to catch mobile prey by picking up the echoes of its own shrieks. Clark’s nutcrackers (members of the crow family) recall the location of thousands of seeds that they have hidden half a year before, while I can’t even remember where I parked my car a few hours ago. Anyone who knows animals can come up with a few more cognitive comparisons that are not in our favor. Instead of a ladder, we are facing an enormous plurality of cognitions with many peaks of specialization. Somewhat paradoxically, these peaks have been called “magic wells” because the more scientists learn about them, the deeper the mystery gets.
We now know, for example, that some crows excel at tool use. In an aviary at Oxford University in 2002, a New Caledonian crow named Betty tried to pull a little bucket with a piece of meat out of a transparent vertical pipe. All she had to work with was a straight metal wire, which didn’t do the trick. Undeterred, Betty used her beak to bend the straight wire into a hook to pull up the bucket. Since no one had taught Betty to do so, it was seen as an example of insight. Apart from dispelling the “birdbrain” notion with which birds are saddled, Betty achieved instant fame by offering proof of tool making outside the primate order. Since this capacity has by now been confirmed by other studies, including one on a cockatoo, we can safely do away with the 1949 book “Man the Tool-Maker” by the British anthropologist Kenneth Oakley, which declared tool fabrication humanity’s defining characteristic. Corvids are a technologically advanced branch on the tree of life with skills that often match those of primates like us.
Convergent evolution (when similar traits, like the wings of birds, bats and insects, appear independently in separate evolutionary branches) allows cognitive capacities to pop up at the most unexpected places, such as face recognition in paper wasps or deceptive tactics in cephalopods. When the males of some cuttlefish species are interrupted by a rival during courtship, they may trick the latter into thinking there is nothing to worry about. On the side of his body that faces his rival, the male adopts the coloring of a female, so that the other believes he is looking at two females. But the courting male keeps his original coloring on the female’s side of his body in order to keep her attention. This two-faced tactic, known as dual-gender signaling, suggests tactical skills of an order no one had ever suspected in a species so low on the natural scale. But of course, talk of “high” and “low” is anathema to biologists, who see every single organism as exquisitely adapted to its own environment.
Now let us return to the accusation of anthropomorphism that we hear every time a new discovery comes along. This accusation works only because of the premise of human exceptionalism. Rooted in religion but also permeating large areas of science, this premise is out of line with modern evolutionary biology and neuroscience. Our brains share the same basic structure with other mammals — no different parts, the same old neurotransmitters.
Brains are in fact so similar across the board that we study fear in the rat’s amygdala to treat human phobias. This doesn’t mean that the planning by an orangutan is of the same order as me announcing an exam in class and my students preparing for it, but deep down there is continuity between both processes. This applies even more to emotional traits.
This is why science nowadays often starts from the opposite end, assuming continuity between humans and animals, while shifting the burden of proof to those who insist on differences. Anyone who asks me to believe that a tickled ape, who almost chokes on his hoarse giggles, is in a different state of mind than a tickled human child has his work cut out for him.
In order to drive this point home, I invented the term “anthropodenial,” which refers to the a priori rejection of humanlike traits in other animals or animallike traits in us. Anthropomorphism and anthropodenial are inversely related: The closer another species is to us, the more anthropomorphism assists our understanding of this species and the greater will be the danger of anthropodenial. Conversely, the more distant a species is from us, the greater the risk that anthropomorphism proposes questionable similarities that have come about independently. Saying that ants have “queens,” “soldiers” and “slaves” is mere anthropomorphic shorthand without much of a connection to the way human societies create these roles.
THE key point is that anthropomorphism is not nearly as bad as people think. With species like the apes — aptly known as “anthropoids” (humanlike) — anthropomorphism is in fact a logical choice. After a lifetime of working with chimpanzees, bonobos and other primates, I feel that denial of the similarities is a greater problem than accepting them. Relabeling a chimpanzee kiss “mouth-to-mouth contact” obfuscates the meaning of a behavior that apes show under the same circumstances as humans, such as when they greet one another or reconcile after a fight. It would be like assigning Earth’s gravity a different name than the moon’s, just because we think Earth is special.
Unjustified linguistic barriers fragment the unity with which nature presents us. Apes and humans did not have enough time to independently evolve almost identical behavior under similar circumstances. Think about this the next time you read about ape planning, dog empathy or elephant self-awareness. Instead of denying these phenomena or ridiculing them, we would do better to ask “why not?”
One reason this whole debate is as heated as it is relates to its moral implications. When our ancestors moved from hunting to farming, they lost respect for animals and began to look at themselves as the rulers of nature. In order to justify how they treated other species, they had to play down their intelligence and deny them a soul. It is impossible to reverse this trend without raising questions about human attitudes and practices. We can see this process underway in the halting of biomedical research on chimpanzees and the opposition to the use of killer whales for entertainment.
Increased respect for animal intelligence also has consequences for cognitive science. For too long, we have left the human intellect dangling in empty evolutionary space. How could our species arrive at planning, empathy, consciousness and so on, if we are part of a natural world devoid of any and all steppingstones to such capacities? Wouldn’t this be about as unlikely as us being the only primates with wings?
Evolution is a gradual process of descent with modification, whether we are talking about physical or mental traits. The more we play down animal intelligence, the more we ask science to believe in miracles when it comes to the human mind. Instead of insisting on our superiority in every regard, let’s take pride in the connections.
There is nothing wrong with the recognition that we are apes — smart ones perhaps, but apes nonetheless. As an ape lover, I can’t see this comparison as insulting. We are endowed with the mental powers and imagination to get under the skin of other species. The more we succeed, the more we will realize that we are not the only intelligent life on earth.
Frans de Waal, a primatologist and professor of psychology at Emory University, is the author, most recently, of “Are We Smart Enough to Know How Smart Animals Are?” from which this essay is adapted.
A version of this op-ed appears in print on April 10, 2016, on page SR1 of the New York edition with the headline: What I Learned Tickling Apes.
A ilusão, que desempenhou um papel estrutural na constituição subjetiva da nossa espécie, pode já não estar ao nosso alcance
Talvez o mal-estar do nosso tempo seja o de que já não é possível escolher entre a pílula azul e a vermelha – ou entre continuar cego ou começar a enxergar o que está por trás da trama dos dias. O mal-estar se deve ao fato de que talvez já não exista a pílula azul – ou já não seja mais possível a ilusão, esta que desempenhou um papel estrutural na constituição subjetiva da nossa espécie ao longo dos milênios.
Se fosse um de nós o membro da resistência disposto a trair os companheiros, a negociar a rendição com as máquinas diante de um suculento filé num restaurante, aqui, agora, e não mais no final dos anos 90, o dilema poderia sofrer um deslocamento. O drama não seria enxergar o filé como filé, no sentido de poder acreditar que ele existe, assim como acreditar que o restaurante existe e que o cenário a que chamamos de mundo existe tal qual está diante dos nossos olhos.
Não. O dilema atual pode ser também este, mas só na medida em que também é outro. O drama é que acreditamos no filé, sabemos que ele existe e sabemos que é gostoso. Desejamos o filé, nos lambuzamos dele e temos prazer com ele. Ao olhar para ele, porém, não enxergamos apenas “o deserto do real”, mas algo muito mais encarnado e cada vez mais inescapável: enxergamos o boi.
É terrível enxergar o boi. E, como os mais sensíveis já descobriram, é impossível deixar de enxergá-lo. Nossa superpopulação de humanos extrapolou a lógica dos vivos, matar para comer. E impôs a escravização e a tortura cotidiana de outras espécies. Milhões de bois, galinhas e porcos nascem apenas para nos alimentar em campos de concentração aos quais damos nomes mais palatáveis. São sacrificados em holocaustos diários sem que nem mesmo tenham tido uma vida.
Animais confinados, presos, às vezes sem sequer poder se mover por uma existência inteira. Criamos profissões capazes de reconhecer em segundos se um pinto é macho ou fêmea para separar as fêmeas que viverão espremidas, muitas vezes sem conseguir sequer abrir as asas, botando ovos e depois virando bandejas no supermercado e jogar os machos para serem moídos ainda vivos no triturador de lixo. Escravidão e tortura/sacrifício e lixo, estes são os destinos que determinamos aos frangos.
Somos os nazistas das outras espécies – e produzimos holocaustos cotidianos
Somos os nazistas das outras espécies. E, se antes era possível ignorar, desqualificando a questão como algo menor ou coisa de “adoradores de alface”, a internet e a disseminação de informações tornaram impossível não enxergar o olho do boi. Ao olhar para o filé, o olho do boi nos olha de volta. O olho vidrado de quem está aterrorizado porque pressente que caminha no corredor da morte, o boi que se caga de medo enquanto é obrigado a dar o passo para o sacrifício, o boi que tenta escapar, mas não encontra saída. O olho do boi alcança até gente como eu, que pode ser colocada na categoria “adoradores de churrasco”.
A publicidade do século 20 perdeu a ressonância em tempos de internet. Porque a ilusão já não é possível. Nada era mais puro do que o leite branco tirado de uma vaquinha no pasto. Era fácil acreditar na imagem bucólica do alimento saudável. Nosso leite vinha do paraíso, de nosso passado rural perdido, da vida nos bosques de Walden. Assim como a longa série de produtos dele originados, como queijo, iogurte e manteiga.
Mas a vaca da imagem não existe. A real é a vaca que nasce em cativeiro, filha de outra escrava. A vaca que quase não se move, cuja existência consiste numa longa série de estupros por instrumentos que se enfiam pelo seu corpo para fecundá-la com o sêmen de outro escravo. Então ela engravida e engravida e engravida de bezerros que dela serão sequestrados para virar filés, para que suas tetas sigam dando leite delas tirados por outras máquinas. E, como sabemos disso, o leite que chega à nossa mesa já não pode mais ser branco, mas vermelho do horror da vaca cujo corpo virou um objeto, a vaca para quem cada dia é tortura, estupro e escravidão.
Para não beber sangue procuramos nas prateleiras leites à base de vegetais. Vegetais não gritam. Soja, apenas um dos tantos exemplos. Bifes de soja, hambúrgueres de soja, linguiças de soja, leite de soja. Mas como ignorar o desmatamento, a destruição de ecossistemas inteiros e com eles toda a vida que lá havia? Como ignorar que a soja pode ter sido plantada em terra indígena e que, enquanto ela vira mercadoria no supermercado, jovens Guarani Kaiowá se enforcam porque já não sabem como viver? Já não é possível fingir que não enxergamos isso. Assim, nem os veganos mais radicais podem se salvar do pecado original.
Os mais sensíveis sentem a textura de suas roupas e sabem que são costuradas com carne humana
Olhamos para nossas roupas e horrorizados sabemos que em algum lugar da linha globalizada de produção há nelas o sangue de crianças, homens e mulheres em regime de trabalho análogo à escravidão. Como o casal que morreu abraçado na fábrica de Bangladesh, gerando a fotografia que comoveu o mundo mas não eliminou o horror que seguiu em escala industrial. Ou mesmo de um imigrante boliviano enfiado num quarto insalubre trabalhando horas e horas por quase nada bem aqui ao lado. Mas os mais sensíveis sentem a textura de suas roupas e sabem que são costuradas com carne humana. E já não sabem como vesti-las. Nem sabem como dar brinquedos para seus filhos porque sabem que os bonecos, os carrinhos, os castelos e os dinossauros contêm neles o sangue das crianças sem infância, ou o de suas mães e pais.
Já não é possível levar crianças a zoológicos ou aquários porque sabemos que a única educação próxima da verdade que receberiam ali é a do horror a que os animais são submetidos para serem exibidos, por melhor que seja a imitação de seu habitat. Lembro uma reportagem que fui fazer num zoológico, planejada para ser divertida, e só pude contar, entre outros horrores, que o babuíno chamado Beto era mantido à custa de Valium, para evitar que arrancasse pedaços do próprio corpo. Mesmo dopado jogava-se contra as grades, atirava fezes nos visitantes e espancava a companheira. Pinky, a elefanta, vivia só. Seus dois companheiros tinham morrido ao cair no fosso tentando escapar do cativeiro. Sabemos hoje que os golfinhos e as baleias dos shows acrobáticos são escravos brutalizados para servir de entretenimento a humanos. E, desde que sabemos, aqueles que gozam com esses espetáculos de morte podem se descobrir não mais como famílias felizes num momento de lazer, como nas imagens dos folhetos publicitários, mas como hordas de sádicos.
No simples ato de acender a luz já existe a consciência de que estamos destruindo o mundo de alguém e de que nada mais será simples. Neste momento, para ficar apenas num exemplo, dezenas de milhares já perderam suas casas no rio Xingu, na Amazônia, para a operação da Hidrelétrica de Belo Monte. Povos indígenas que vivem na região atingida já não conseguem suportar o aumento exponencial de mosquitos desde que o lago da usina começou a encher, alterando o ecossistema e dizimando culturas, no que já foi denunciado pelo Ministério Público Federal como etnocídio. Os impactos mal começaram e, em menos de três meses, mais de 16 toneladas de peixes morreram. E talvez também esteja chegando ao fim o tempo em que ainda é aceitável contar vidas por toneladas, mesmo que seja a vida de peixes. Ou a morte de peixes. Um dedo no interruptor e uma cadeia de mortes. E agora também já sabemos disso.
Ao pedir um café e um pão com manteiga na padaria, nos implicamos numa cadeia de horrores
O tempo das ilusões acabou. Nenhum ato do nosso cotidiano é inocente. Ao pedir um café e um pão com manteiga na padaria, nos implicamos numa cadeia de horrores causados a animais e a humanos envolvidos na produção. Cada ato banal implica uma escolha ética – e também uma escolha política.
A descrição das atrocidades que cometemos rotineiramente pode aqui seguir por milhares de caracteres. Comemos, vestimos, nos entretemos, transportamos e nos transportamos à custa da escravidão, da tortura e do sacrifício de outras espécies e também dos mais frágeis da nossa própria espécie. Somos o que de pior aconteceu ao planeta e a todos que o habitam. A mudança climática já anuncia que não apenas tememos a catástrofe, mas nos tornamos a catástrofe. Desta vez, não só para todos os outros, mas também para nós mesmos.
Já não é possível a pílula azul – ou já não é possível à adesão às ilusões. Há várias implicações profundas numa época em que o conhecimento não liberta, mas condena. A começar, talvez, pela pergunta: quem é o inocente num mundo em que a inocência já não é possível? Seria o inocente o pior humano de todos? Seria o inocente um psicopata?
O que seremos nós, subjetivamente, agora que estamos condenados a enxergar? As redes sociais têm nos dado algumas pistas. O que a internet fez foi arrancar da humanidade as ilusões sobre si mesma. O cotidiano nas redes sociais nos mostrou a verdade que sempre esteve lá, mas era protegida – ou mediada – pelo mundo das aparências. Sobre isso já escrevi um artigo, chamado A boçalidade do mal, que pode ser lido aqui. As implicações de perder este véu tão arduamente tecido são profundas e recém começam a ser investigadas. O impacto sobre a subjetividade estrutural de nossa espécie é tremendo, exatamente porque é estrutural e desabou num espaço de tempo muito curto, quase num soluço.
Já não é mais possível pensar apenas em humanos quando se aborda o tema dos direitos
O que faremos diante da impossibilidade da pílula azul, a que garantia as ilusões? A ridicularização daqueles que levantam esse tema ainda é um caminho, mas convencem menos que no passado. Também a piada se torna anacrônica. As interrogações vêm mudando, e já não é possível afirmar, sem revelar considerável ignorância, inclusive sobre a ciência produzida, que os animais não têm vida mental nem emocional, são “irracionais”. Ou, lembrando um argumento religioso, “que não têm alma”. Toda a ideologia que um dia justificou a escravidão de humanos, até que foi questionada, derrubada e transformada numa mancha de crime e vergonha na história da humanidade, passou a ser confrontada também com relação aos animais.
Cada vez mais as outras espécies começam a ser vistas como diferentes – e não mais como inferiores. Assim, o que se coloca no campo da ética são questões fascinantes e muito mais espinhosas. Mesmo o termo “direitos humanos” passa a ser questionável, porque pensar apenas em “humanos” já não é mais possível. No momento em que nos tornamos a própria definição de catástrofe, o conceito de “espécie”, em sua expressão cultural, se desloca. Outras formas de compreender e nomear o lugar dos humanos ganham espaço no horizonte filosófico e no exercício da política.
Resta o cinismo, sempre o último reduto. Dizer que, diante de mais de 7 bilhões de seres humanos ocupando o planeta e crescendo, não há outra maneira a não ser comer e vestir exploração, escravidão e tortura é a afirmação mais óbvia. É a afirmação expandida usada para todas as desigualdades de direitos. Desde que não seja eu – ou os meus – os sacrificados, tudo bem.
Vale a pena dedicar um parágrafo aos cínicos, essa categoria que prolifera com o ímpeto de um Aedes aegypti no Brasil e no mundo. O cínico é aquele que olha com calculado enfado para todos os outros, porque ele acredita que entende o mundo como ele de fato é. Ele é o que sabe das coisas, o único esperto. Todos os outros são tolinhos com ideias irreais. O cínico é aquele que deixa o mundo como está. Mas talvez, neste momento, o cínico seja justamente o inocente. Sua inocência consiste em acreditar que a pílula azul ainda está disponível.
Como ser ético num mundo sem ilusões, em que cada ato implica na tortura e no sacrifício de um outro?
Há um preço para enxergar e, mesmo assim, assumir o extermínio cotidiano como dado, como parte intrínseca da condição de ser um humano. Nem toda a crescente gourmetização da comida, nem todas as narrativas ficcionais que contam uma história idílica sobre a origem daquele produto, nada ocultará esse preço. E nada reduzirá seu impacto subjetivo. Não é fácil viver na pele do algoz. Não é simples viver sabendo-se. Aquele que se olha no espelho e se enxerga carregará essa autoimagem consigo. E se tornará algo que já não é mais o mesmo.
Há uma imagem recente que pode dar algumas pistas sobre esse caminho. Numa praia da Argentina, um golfinho foi carregado por turistas. Alguns dizem que ainda estava vivo, outros que já estava morto. Vivo ou morto, os turistas preocuparam-se apenas com tirar selfies para postar nas redes sociais. O site de humor Sensacionalista postou: “Golfinho morre ao ser retirado do mar para turistas fazerem selfie e Deus anuncia recall do ser humano”.
Ainda assim, quem se horrorizou com a falta de horror alheia, à noite seguiu diante do olho do boi. O que fazer diante do olho do boi? Como ser ético num mundo sem ilusões, em que cada ato implica na tortura e no sacrifício de um outro, humano e não humano? Se somos os nazistas das outras espécies, quando não da mesma, aceitar que assim é não seria se tornar um Eichmann, o nazista julgado em Jerusalém que alegou apenas cumprir ordens, o homem tão banalmente ordinário que inspirou a filósofa Hannah Arendt a criar o conceito da “banalidade do mal”? Não seríamos, aos olhos do boi, todos Eichmann, justificando-nos pelo senso comum de que assim é e se faz o que é preciso para sobreviver? Se sim, o que implica viver assumidamente nesta pele?
Talvez estejamos, como espécie que se pensa, diante de um dos maiores dilemas éticos da nossa história. Sem poder optar pela pílula azul, a das ilusões, condenados à pílula vermelha, a que nos obriga a enxergar, como construir uma escolha que volte a incluir a ética? Como não paralisar diante do espelho, reduzidos ou ao horror ou ao cinismo, eliminando a possibilidade de transformação? Como nos mover?
Diante do filé que desejamos e do olho boi que nos interroga, há pelo menos uma hipótese cada vez mais forte: o inocente é um assassino.
Date: November 24, 2015
Source: Princeton University
Summary: Researchers report for the first time that the ‘living’ bridges army ants of the species Eciton hamatum build with their bodies are more sophisticated than scientists knew. The ants automatically assemble with a level of collective intelligence that could provide new insights into animal behavior and even help in the development of intuitive robots that can cooperate as a group.
Without any orders or direction, individuals from the rank and file instinctively stretch across the opening, clinging to one another as their comrades-in-arms swarm across their bodies. But this is no force of superhumans. They are army ants of the species Eciton hamatum, which form “living” bridges across breaks and gaps in the forest floor that allow their famously large raiding swarms to travel efficiently.
Researchers from Princeton University and the New Jersey Institute of Technology (NJIT) report for the first time that these structures are more sophisticated than scientists knew. The ants exhibit a level of collective intelligence that could provide new insights into animal behavior and even help in the development of intuitive robots that can cooperate as a group, the researchers said.
Ants of E. hamatum automatically form living bridges without any oversight from a “lead” ant, the researchers report in the journal Proceedings of the National Academy of the Sciences. The action of each individual coalesces into a group unit that can adapt to the terrain and also operates by a clear cost-benefit ratio. The ants will create a path over an open space up to the point when too many workers are being diverted from collecting food and prey.
“These ants are performing a collective computation. At the level of the entire colony, they’re saying they can afford this many ants locked up in this bridge, but no more than that,” said co-first author Matthew Lutz, a graduate student in Princeton’s Department of Ecology and Evolutionary Biology.
“There’s no single ant overseeing the decision, they’re making that calculation as a colony,” Lutz said. “Thinking about this cost-benefit framework might be a new insight that can be applied to other animal structures that people haven’t thought of before.”
The research could help explain how large groups of animals balance cost and benefit, about which little is known, said co-author Iain Couzin, a Princeton visiting senior research scholar in ecology and evolutionary biology, and director of the Max Planck Institute for Ornithology and chair of biodiversity and collective behavior at the University of Konstanz in Germany.
Previous studies have shown that single creatures use “rules of thumb” to weigh cost-and-benefit, said Couzin, who also is Lutz’s graduate adviser. This new work shows that in large groups these same individual guidelines can eventually coordinate group-wide, he said — the ants acted as a unit although each ant only knew its immediate circumstances.
“They don’t know how many other ants are in the bridge, or what the overall traffic situation is. They only know about their local connections to others, and the sense of ants moving over their bodies,” Couzin said. “Yet, they have evolved simple rules that allow them to keep reconfiguring until, collectively, they have made a structure of an appropriate size for the prevailing conditions.
“Finding out how sightless ants can achieve such feats certainly could change the way we think of self-configuring structures in nature — and those made by man,” he said.
Ant-colony behavior has been the basis of algorithms related to telecommunications and vehicle routing, among other areas, explained co-first author Chris Reid, a postdoctoral research associate at the University of Sydney who conducted the work while at NJIT. Ants exemplify “swarm intelligence,” in which individual-level interactions produce coordinated group behavior. E. hamatum crossings assemble when the ants detect congestion along their raiding trail, and disassemble when normal traffic has resumed.
Previously, scientists thought that ant bridges were static structures — their appearance over large gaps that ants clearly could not cross in midair was somewhat of a mystery, Reid said. The researchers found, however, that the ants, when confronted with an open space, start from the narrowest point of the expanse and work toward the widest point, expanding the bridge as they go to shorten the distance their compatriots must travel to get around the expanse.
“The amazing thing is that a very elegant solution to a colony-level problem arises from the individual interactions of a swarm of simple worker ants, each with only local information,” Reid said. “By extracting the rules used by individual ants about whether to initiate, join or leave a living structure, we could program swarms of simple robots to build bridges and other structures by connecting to each other.
“These robot bridges would exhibit the beneficial properties we observe in the ant bridges, such as adaptability to local conditions, real-time optimization of shape and position, and rapid construction and deconstruction without the need for external building materials,” Reid continued. “Such a swarm of robots would be especially useful in dangerous and unpredictable conditions, such as natural disaster zones.”
Radhika Nagpal, a professor of computer science at Harvard University who studies robotics and self-organizing biological systems, said that the findings reveal that there is “something much more fundamental about how complex structures are assembled and adapted in nature, and that it is not through a supervisor or planner making decisions.”
Individual ants adjusted to one another’s choices to create a successful structure, despite the fact that each ant didn’t necessarily know everything about the size of the gap or the traffic flow, said Nagpal, who is familiar with the research but was not involved in it.
“The goal wasn’t known ahead of time, but ‘emerged’ as the collective continually adapted its solution to the environmental factors,” she said. “The study really opens your eyes to new ways of thinking about collective power, and has tremendous potential as a way to think about engineering systems that are more adaptive and able to solve complex cost-benefit ratios at the network level just through peer-to-peer interactions.”
She compared the ant bridges to human-made bridges that automatically widened to accommodate heavy vehicle traffic or a growing population. While self-assembling road bridges may be a ways off, the example illustrates the potential that technologies built with the same self-assembling capabilities seen in E. hamatum could have.
“There’s a deep interest in creating robots that don’t just rely on themselves, but can exploit the group to do more — and self-assembly is the ultimate in doing more,” Nagpal said. “If you could have small simple robots that were able to navigate complex spaces, but could self-assemble into larger structures — bridges, towers, pulling chains, rafts — when they face something they individually did not have the ability to do, that’s a huge increase in power in what robots would be capable of.”
The spaces E. hamatum bridges are not dramatic by human standards — small rifts in the leaf cover, or between the ends of two sticks. Bridges will be the length of 10 to 20 ants, which is only a few centimeters, Lutz said. That said, E. hamatum swarms form several bridges during the course of a day, which can see the back-and-forth of thousands of ants.
“The bridges are something that happen numerous times every day. They’re creating bridges to optimize their traffic flow and maximize their time,” Lutz said.
“When you’re moving hundreds of thousands of ants, creating a little shortcut can save a lot of energy,” he said. “This is such a unique behavior. You have other types of ants forming structures out of their bodies, but it’s not such a huge part of their lives and daily behavior.”
The research also included Scott Powell, an army-ant expert and assistant professor of biology at George Washington University; Albert Kao, a postdoctoral fellow at Harvard who received his doctorate in ecology and evolutionary biology from Princeton in 2015; and Simon Garnier, an assistant professor of biological sciences at NJIT who studies swarm intelligence and was once a postdoctoral researcher in Couzin’s lab at Princeton.
To conduct their field experiments, Lutz and Reid constructed a 1.5-foot-tall apparatus with ramps on both sides and adjustable arms in the center with which they could adjust the size of the gap. They then inserted the apparatus into active E. hamatum raiding trails that they found in the forests of Barro Colorado Island, Panama. Because ants follow one another’s chemical scent, Lutz and Reid used sticks and leaves from the ants’ trail to get them to reform their column across the device.
Lutz and Reid observed how the ants formed bridges across gaps that were set at angles of 12, 20, 40 and 60 degrees. They gauged how much travel-distance the ants saved with their bridge versus the surface area (in centimeters squared) of the bridge itself. Twelve-degree angles shaved off the most distance (around 11 centimeters) while taking up the fewest workers. Sixty-degree angles had the highest cost-to-benefit ratio. Interestingly, the ants were willing to expend members for 20-degree angles, forming bridges up to 8 centimeters squared to decrease their travel time by almost 12 centimeters, indicating that the loss in manpower was worth the distance saved.
Lutz said that future research based on this work might compare these findings to the living bridges of another army ant species, E. burchellii, to determine if the same principles are in action.
The paper, “Army ants dynamically adjust living bridges in response to a cost-benefit trade-off,” was published Nov. 23 by Proceedings of the National Academy of Sciences. The work was supported by the National Science Foundation (grant nos. PHY-0848755, IOS0-1355061 and EAGER IOS-1251585); the Army Research Office (grant nos. W911NG-11-1-0385 and W911NF-14-1-0431); and the Human Frontier Science Program (grant no. RGP0065/2012).
- Chris R. Reid, Matthew J. Lutz, Scott Powell, Albert B. Kao, Iain D. Couzin, Simon Garnier. Army ants dynamically adjust living bridges in response to a cost–benefit trade-off. Proceedings of the National Academy of Sciences, 2015; 201512241 DOI: 10.1073/pnas.1512241112
For centuries it has been thought that culture is what distinguishes humans from other animals, but over the past decade this idea has been repeatedly called into question. Cultural variation has been identified in a growing number of species in recent years, ranging from primates to cetaceans. Chimpanzees, our closest living relatives, show the most diverse cultures aside from humans, most notably, in their use of a wide variety of tools.
The method traditionally used to establish the presence of culture in wild animals compares behavioural variation across populations and excludes all behavioural patterns that can be explained by genetic or environmental differences across sites. Nevertheless, it is impossible to conclusively rule out the influence of genetics and environmental conditions in geographically distant populations.
To circumnavigate this problem, researchers, led by Dr. Kathelijne Koops, took a new approach. “We compared neighbouring chimpanzee groups living under similar environmental conditions, which allows for the investigation of fine scale cultural differences, whilst keeping genetics constant,” said Koops.
She and colleagues from Kyoto University and Freie Universität Berlin compared the length of tools used for ‘ant-dipping’ between two neighbouring chimpanzee communities, M-group and S-group, in the Kalinzu Forest, Uganda. Dipping for army ants is one of the hallmark examples of culture in chimpanzees and involves the use of a stick to extract the highly aggressive army ants from their underground nests.
Previous research has shown that ant-dipping tool length varied across chimpanzee study sites in relation to the army ant species (Dorylus spp.) that were present. So Koops compared the availability of the different species of army ants and the length of dipping tools used in the two adjacent chimpanzee communities.
The researchers found that M-group tools were significantly longer than S-group tools, despite identical army ant species availability. Considering the lack of ecological differences between the two communities, the tool length difference was concluded to be cultural. “Our findings highlight how cultural knowledge can generate small-scale cultural diversification in neighbouring groups,” said Koops.
“Given the close evolutionary relationship between chimpanzees and humans, insights into what drives cultural diversification in our closest living relatives will in turn shed light on how cultural differences emerge and are maintained between adjacent groups in human societies,” said Koops, who conducted the work at Cambridge University’s Division of Biological Anthropology and at Zurich University’s Anthropological Institute and Museum.
The research is published today in the Nature journal Scientific Reports.
Primatas que usam lanças podem fornecer indícios sobre origem das sociedades humanas
Na quente savana senegalesa se encontra o único grupo de chimpanzés que usa lanças para caçar animais com os quais se alimenta. Um ou outro grupo de chimpanzés foi visto portando ferramentas para a captura de pequenos mamíferos, mas esses, na comunidade de Fongoli, caçam regularmente usando ramos afiados. Esse modo de conseguir alimento é um uso cultural consolidado para esse grupo de chimpanzés.
Além dessa inovação tecnológica, em Fongoli ocorre também uma novidade social que os distingue dos demais chimpanzés estudados na África: há mais tolerância, maior paridade dos sexos na caça e os machos mais corpulentos não passam com tanta frequência por cima dos interesses dos demais, valendo-se de sua força. Para os pesquisadores que vêm observando esse comportamento há uma década esses usos poderiam, além disso, oferecer pistas sobre a evolução dos ancestrais humanos.
“São a única população não humana conhecida que caça vertebrados com ferramentas de forma sistemática, por isso constituem uma fonte importante para a hipótese sobre o comportamento dos primeiros hominídeos, com base na analogia”, explicam os pesquisadores do estudo no qual formularam suas conclusões depois de dez anos observando as caçadas de Fongoli. Esse grupo, liderado pela antropóloga Jill Pruetz, considera que esses animais são um bom exemplo do que pode ser a origem dos primeiros primatas eretos sobre duas patas.
Na sociedade Fongoli as fêmeas realizam exatamente a metade das caçadas com lança. Graças à inovação tecnológica que representa a conversão de galhos em pequenas lanças com as quais se ajudam para caçar galagos – pequenos macacos muito comuns nesse entorno –, as fêmeas conseguem certa independência alimentar. Na comunidade de Gombe, que durante muitos anos foi estudada por Jane Goodall, os machos arcam com cerca de 90% do total das presas; em Fongoli, somente 70%. Além disso, em outros grupos de chimpanzés os machos mais fortes roubam uma de cada quatro presas caçadas pelas fêmeas (sem ferramentas): em Fongoli, apenas 5%.
“Em Fongoli, quando uma fêmea ou um macho de baixo escalão captura uma presa, permitem que ele fique com ela e a coma. Em outros lugares, o macho alfa ou outro macho dominante costuma tomar-lhe a presa. Assim, as fêmeas obtêm pouco benefício da caça, se outro chimpanzé lhe tira sua presa”, afirma Pruetz. Ou seja, o respeito dos machos de Fongoli pelas presas obtidas por suas companheiras serviria de incentivo para que elas se decidam a ir à caça com mais frequência do que as de outras comunidades. Durante esses anos de observação, praticamente todos os chimpanzés do grupo – cerca de 30 indivíduos – caçaram com ferramentas,
O clima seco faz com que os macacos mais acessíveis em Fongoli sejam os pequenos galagos, e não os colobos vermelhos – os preferidos dos chimpanzés em outros lugares da África –, que são maiores e difíceis de capturar por outros que não sejam os machos mais rápidos e corpulentos. Quase todos os episódios de caça com lanças observados (três centenas) se deram nos meses úmidos, nos quais outras fontes de alimento são escassas.
A savana senegalesa, com poucas árvores, é um ecossistema que tem uma importante semelhança com o cenário em que evoluíram os ancestrais humanos. Ao contrário de outras comunidades africanas, os chimpanzés de Fongoli passam a maior parte do tempo no chão, e não entre os galhos. A excepcional forma de caça de Fongoli leva os pesquisadores a sugerir em seu estudo que os primeiros hominídeos provavelmente intensificaram o uso de ferramentas tecnológicas para superar as pressões ambientais, e que eram até mesmo “suficientemente sofisticados a ponto de aperfeiçoar ferramentas de caça”.
“Sabemos que o entorno tem um impacto importante no comportamento dos chimpanzés”, afirma o primatólogo Joseph Call, do Instituto Max Planck. “A distribuição das árvores determina o tipo de caça: onde a vegetação é mais frondosa, a caçada é mais cooperativa em relação a outros entornos nos quais é mais fácil seguir a presa, e eles são mais individualistas”, assinala Call.
No entanto, Call põe em dúvida que essas práticas de Fongoli possam ser consideradas caçadas com lança propriamente ditas, já que para ele lembram mais a captura de formigas e cupins usando palitos, algo mais comum entre os primatas. “A definição de caça que os pesquisadores estabelecem em seu estudo não se distingue muito do que fazem colocando um raminho em um orifício para conseguir insetos para comer”, diz Call. Os chimpanzés de Fongoli cutucam com paus os galagos quando eles se escondem em cavidades das árvores para forçá-los a sair e, uma vez fora, lhes arrancam a cabeça com uma mordida. “É algo que fica entre uma coisa e a outra”, argumenta.
Esses antropólogos acreditam que o achado permite pensar que os primeiros hominídeos eretos também usavam lanças
Pruetz responde a esse tipo de crítica dizendo que se trata de uma estratégia para evitar que o macaco os morda ou escape, uma situação muito diferente daquela de colocar um galho em um orifício para capturar bichos. Se for o mesmo, argumentam Pruetz e seus colegas, a pergunta é “por que os chimpanzés de outros grupos não caçam mais”.
Além do caso particular, nem sequer está encerrado o debate sobre se os chimpanzés devem ser considerados modelos do que foram os ancestrais humanos. “Temos de levar em conta que o bonobo não faz nada disso e é tão próximo de nós como o chimpanzé”, defende Call. “Pegamos o chimpanzé por que nos cai bem para assinalar determinadas influências comuns. É preciso ter muito cuidado e não pesquisar a espécie dependendo do que queiramos encontrar”, propõe.