Arquivo da tag: Evolução

Fossil analysis pushes back human split from other primates by 2 million years (Los Alamos National Laboratory)

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16-FEB-2016

Nature paper places human evolution in Africa, not Eurasia

DOE/Los Alamos National Laboratory

IMAGEIMAGE: TEAM ANALYSIS OF THESE 8-MILLION-YEAR-OLD CHORORAPITHECUS TEETH FOSSILS PROVIDED INSIGHTS INTO THE HUMAN-GORILLA EVOLUTIONARY SPLIT. CREDIT: GEN SUWA

LOS ALAMOS, N.M., February 16, 2015–A paper in the latest issue of the journal Nature suggests a common ancestor of apes and humans, Chororapithecus abyssinicus, evolved in Africa, not Eurasia, two million years earlier than previously thought.

“Our new research supports early divergence: 10 million years ago for the human-gorilla split and 8 million years ago for our split from chimpanzees,” said Los Alamos National Laboratory geologist and senior team member Giday WoldeGabriel. “That’s at least 2 million years earlier than previous estimates, which were based on genetic science that lacked fossil evidence.”

“Our analysis of C. abyssinicus fossils reveals the ape to be only 8 million years old, younger than previously thought. This is the time period when human and African ape lines were thought to have split, but no fossils from this period had been found until now,” WoldeGabriel said.

Chimpanzees, gorillas, orangutans and humans compose the biological family Hominidae. Our knowledge of hominid evolution–that is, when and how humans evolved away from the great ape family tree–has significantly increased in recent years, aided by unearthed fossils from Ethiopia, including the C. abyssinicus, a species of great ape.

The renowned international team that discovered the extinct gorilla-like species C. abyssinicus(reported in the journal Nature in 2007) reports new field observations and geological techniques that the authors say revise the age-constraint of the human split from their brethren.

The authors’ new paper, “New geological and palaeontological age constraint for the gorilla-human lineage split,” was published this week in Nature. WoldeGabriel coauthored the paper and his role was to characterize the volcanic ash and provide chemistry for local and regional correlation of the ashes sandwiching the fossils from Ethiopia’s Chorora area, a region where copious volcanic eruptions and earthquakes entombed fossils recently uplifted via ground motion and erosion.

Filling Gaps in the Fossil Record

Most of the senior members of the Chorora research team also belong to the Middle Awash project team that has recovered the fossil remains of at least eight hominid species, including some of the earliest hominids, spanning nearly 6 million years.

In the 1990s, before this team excavated the gorilla-like C. abyssinicus, they discovered the nearly intact skeleton of the 4.4-million-year-old species Ardipithecus ramidus (nicknamed “Ardi”) and its relative, the million-year-older species Ardipithecus kadabba. These Ardipithecusfossils were the earliest ancestor of humans after they diverged from the main ape lineage of the primate family tree, neither ape-like nor chimp-like, yet not human either. Notably, both were bipedal–they walked upright.

While the team was still investigating Ardi and Kadabba, they published their results about C. abyssinicus. From the collection of nine fossilized teeth from multiple C. abyssinicus individuals, the team surmised that these teeth were gorilla-like, adapted for a fibrous diet. Based on their research from the Chorora, Kadabba and Ardi finds, the team says the common ancestor of chimps and humans lived earlier than had been evidenced by genetic and molecular studies, which placed the split about 5 million years ago.

According to the paper, C. abyssinicus revealed answers about gorilla lineage but also provided fossil evidence that our common ancestor migrated from Africa, not Eurasia, where fossils were more prolific prior to this discovery of multiple skeletons. While some skeptics say that more fossil evidence is needed before they accept this team’s conclusions, many agree that the discovery of a fossil ape from this time period is important since only one other had been found.

Extensive Analysis Provides New Evidence

WoldeGabriel and the research team used a variety of methods to determine the age of teeth they found at the Chorora Formation. They estimated the age of the volcanic rocks and sediments that encased the fossils with argon-dating and paleomagnetic methods. The team investigated patterns of magnetic reversals–another method to determine age based on knowledge about an era’s magnetic orientation–and calibrated the sediments containing the fossils using Geomagnetic Polarity Time Scale (GPTS).

Through fieldwork, volcanic ash chemistry and geochronology, WoldeGabriel helped nail down the age of the fossils to approximately 8 million years old. Based on this new fossil evidence and analysis, the team suggests that the human branch of the tree (shared with chimpanzees) split away from gorillas about 10 million years ago–at least 2 million years earlier than previously claimed.

New appreciation for human micro biome leads to greater understanding of human health (Science Daily)

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Date: February 14, 2016

Source: University of Oklahoma

Summary: Anthropologists are studying the ancient and modern human micro biome and the role it plays in human health and disease. By applying genomic and proteomic sequencing technologies to ancient human microbiomes, such as coprolites and dental calculus, as well as to contemporary microbiomes in traditional and industrialized societies, Researchers are advancing the understanding of the evolutionary history of our microbial self and its impact on human health today.

University of Oklahoma anthropologists are studying the ancient and modern human microbiome and the role it plays in human health and disease. By applying genomic and proteomic sequencing technologies to ancient human microbiomes, such as coprolites and dental calculus, as well as to contemporary microbiomes in traditional and industrialized societies, OU researchers are advancing the understanding of the evolutionary history of our microbial self and its impact on human health today.

Christina Warinner, professor in the Department of Anthropology, OU College of Arts and Sciences, will present, “The Evolution and Ecology of Our Microbial Self,” during the American Association for the Advancement of Science panel on Evolutionary Biology Impacts on Medicine and Public Health, at 1:30 pm, Sunday, Feb. 14, 2016 in the Marriott Marshall Ballroom West, Washington, DC. Warinner will discuss how major events, such as the invention of agriculture and the advent of industrialization, have affected the human microbiome.

“We don’t have a complete picture of the microbiome,” Warinner said. “OU research indicates human behavior over the past 2000 years has impacted the gut microbiome. Microbial communities have become disturbed, but before we can improve our health, we have to understand our ancestral microbiome. We cannot make targeted or informed interventions until we know that. Ancient samples allow us to directly measure changes in the human microbiome at specific times and places in the past.”

Warinner and colleague, Cecil M. Lewis, Jr., co-direct OU’s Laboratories of Molecular Anthropology and Microbiome Research and the research focused on reconstructing the ancestral human oral and gut microbiome, addressing questions concerning how the relationship between humans and microbes has changed through time and how our microbiomes influence health and disease in diverse populations, both today and in the past. Warinner and Lewis are leaders in the field of paleogenomics, and the OU laboratories house the largest ancient DNA laboratory in the United States.

Warinner is pioneering the study of ancient human microbiomes, and in 2014 she published the first detailed metagenomics and metaproteomic characterization of the ancient oral microbiome in the journal Nature Genetics. In 2015, she published a study on the identification of milk proteins in ancient dental calculus and the reconstruction of prehistoric European dairying practices. In the same year, she was part of an international team that published the first South American hunter-gatherer gut microbiome and identified Treponema as a key missing ancestral microbe in industrialized societies.

The Big Search to Find Out Where Dogs Come From (New York Times)

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An ancient canine skull at the Royal Belgian Institute of Natural Sciences. Scientists are still debating exactly when and where the ancient human-canine bond originated. ANDREW TESTA FOR THE NEW YORK TIMES

By JAMES GORMAN

JANUARY 18, 2016

OXFORD, England — Before humans milked cows, herded goats or raised hogs, before they invented agriculture, or written language, before they had permanent homes, and most certainly before they had cats, they had dogs.

Or dogs had them, depending on how you view the human-canine arrangement. But scientists are still debating exactly when and where the ancient bond originated. And a large new study being run out of the University of Oxford here, with collaborators around the world, may soon provide some answers.

Scientists have come up with a broad picture of the origins of dogs. First off, researchers agree that they evolved from ancient wolves. Scientists once thought that some visionary hunter-gatherer nabbed a wolf puppy from its den one day and started raising tamer and tamer wolves, taking the first steps on the long road to leashes and flea collars. This is oversimplified, of course, but the essence of the idea is that people actively bred wolves to become dogs just the way they now breed dogs to be tiny or large, or to herd sheep.

The prevailing scientific opinion now, however, is that this origin story does not pass muster. Wolves are hard to tame, even as puppies, and many researchers find it much more plausible that dogs, in effect, invented themselves.

Greger Larson, a biologist in the archeology department at the University of Oxford, hopes a large database of ancient DNA will help determine where and when the domestication of dogs occurred. ANDREW TESTA FOR THE NEW YORK TIMES

Imagine that some ancient wolves were slightly less timid around nomadic hunters and scavenged regularly from their kills and camps, and gradually evolved to become tamer and tamer, producing lots of offspring because of the relatively easy pickings. At some point, they became the tail-wagging beggar now celebrated as man’s best friend.

Some researchers question whether dogs experience feelings like love and loyalty, or whether their winning ways are just a matter of instincts that evolved because being a hanger-on is an easier way to make a living than running down elk. Raymond Coppinger, a professor emeritus of biology at Hampshire College, noted in his landmark 2001 book, “Dogs,” that “best friend” is not an “ecological definition.” And he suggested that “the domestic house dog may have evolved into a parasite.”

Researchers also point out that of the estimated one billion dogs in the world, only a quarter of them are pets. The vast majority of dogs run free in villages, scavenge food at dumps, cadge the odd handout and cause tens of thousands of human deaths each year from rabies. They are sometimes friendly, but not really friends.

Modern dogs are different from modern wolves in numerous ways. They eat comfortably in the presence of people, whereas wolves do not. Their skulls are wider and snouts shorter. They do not live in pack structures when they are on their own, and so some scientists scoff at dog-training approaches that require the human to act as pack leader.

Jawbone and teeth fragments housed at the Oxford Museum of Natural History. ANDREW TESTA FOR THE NEW YORK TIMES

Wolves mate for the long haul and wolf dads help with the young, while dogs are completely promiscuous and the males pay no attention to their offspring. Still, dogs and wolves interbreed easily and some scientists are not convinced that the two are even different species, a skepticism that reflects broader debates in science about how to define a species, and how much the category is a fact of nature as opposed to an arbitrary line drawn by humans.

Tracing the Origins

If current divisions between species are murky, the past lies in deep darkness. Scientists generally agree that there is good evidence that dogs were domesticated around 15,000 years ago. By 14,000 years ago, people were burying dogs, sometimes along with humans. But some biologists argue, based on DNA evidence and the shape of ancient skulls, that dog domestication occurred well over 30,000 years ago.

And as to where the process occurred, researchers studying dog and wolf DNA — most of it modern but some from ancient sources — have argued in recent years that dogs originated in East Asia, Mongolia, Siberia, Europe and Africa.

Arden Hulme-Beaman cutting a piece from an ancient skull for DNA testing at the Royal Belgian Institute of Natural Sciences in Brussels. ANDREW TESTA FOR THE NEW YORK TIMES

One reason for the conflicting theories, according to Greger Larson, a biologist in the archaeology department at the University of Oxford, is that dog genetics are a mess. In an interview at his office here in November, he noted that most dog breeds were invented in the 19th century during a period of dog obsession that he called “the giant whirlwind blender of the European crazy Victorian dog-breeding frenzy.”

That blender, as well as random breeding by dogs themselves, and interbreeding with wolves at different times over at least the last 15,000 years, created a “tomato soup” of dog genetics, for which the ingredients are very hard to identify, Dr. Larson said.

The way to find the recipe, Dr. Larson is convinced, is to create a large database of ancient DNA to add to the soup of modern canine genetics. And with a colleague, Keith Dobney at the University of Aberdeen, he has persuaded the Who’s Who of dog researchers to join a broad project, with about $2.5 million in funding from the Natural Environment Research Council in England and the European Research Council, to analyze ancient bones and their DNA.

Robert Wayne, an evolutionary biologist at U.C.L.A. who studies the origin of dogs and is part of the research, said, “There’s hardly a person working in canine genetics that’s not working on that project.”

A wolf on display at the Oxford Museum of Natural History. ANDREW TESTA FOR THE NEW YORK TIMES

That is something of a triumph, given the many competing theories in this field. “Almost every group has a different origination hypothesis,” he said.

But Dr. Larson has sold them all on the simple notion that the more data they have, the more cooperative the effort is, the better the answers are going to be. His personality has been crucial to promoting the team effort, said Dr. Wayne, who described Dr. Larson as “very outgoing, gregarious.” Also, Dr. Wayne added, “He has managed not to alienate anyone.”

Scientists at museums and universities who are part of the project are opening up their collections. So to gather data, Dr. Larson and his team at Oxford have traveled the world, collecting tiny samples of bone and measurements of teeth, jaws and occasionally nearly complete skulls from old and recent dogs, wolves and canids that could fall into either category. The collection phase is almost done, said Dr. Larson, who expects to end up with DNA from about 1,500 samples, and photographs and detailed measurements of several thousand.

Scientific papers will start to emerge this year from the work, some originating in Oxford, and some from other institutions, all the work of many collaborators.

Dr. Larson is gambling that the project will be able to determine whether the domestication process occurred closer to 15,000 or 30,000 years ago, and in what region it took place. That’s not quite the date, GPS location and name of the ancient hunter that some dog lovers might hope for.

But it would be a major achievement in the world of canine science, and a landmark in the analysis of ancient DNA to show evolution, migrations and descent, much as studies of ancient hominid DNA have shown how ancient humans populated the globe and interbred with Neanderthals.

And why care about the domestication of dogs, beyond the obsessive interest so many people have in their pets? The emergence of dogs may have been a watershed.

“Maybe dog domestication on some level kicks off this whole change in the way that humans are involved and responding to and interacting with their environment,” he added. “I don’t think that’s outlandish.”

Shepherding the Research

Dr. Larson is no stranger to widely varying points of view. He is an American, but recently became a British citizen as well. His parents are American and he visited the United States often as a child, but he was born in Bahrain and grew up in Turkey and Japan, places where his parents were teaching in schools on American military bases.

He graduated from Claremont McKenna College in California and received his Ph.D. at Oxford. In between college and graduate studies, he spent a year searching for the bed of an ancient river in Turkmenistan, and another couple of years setting up an environmental consulting office in Azerbaijan. He had an interest in science as an undergraduate, and some background from a college major in environment, economics and politics, but no set career plans. Instead, his career grew out of intense curiosity, a knack for making friends and a willingness to jump at an opportunity, like the time he managed to tag along on an archaeological dig.

He was staying in Ashgabat, Turkmenistan, and a local man who had helped him rent an old Soviet truck to explore the desert told him some Westerners were arriving to go on a dig, so he wangled his way onto one of the trucks.

“I think everybody there thought I was with somebody else,” Dr. Larson said.

By the time the group stopped to rest and someone asked him who he was, it was too late to question whether he really belonged. “I was a complete stowaway,” he said.

But he could move dirt and speak Russian, and he had some recently acquired expertise — in college drinking games — that he said was in great demand at night. By luck, he said, the researchers on the dig turned out to be “the great and the good of British neolithic archaeology.” One of them was Chris Gosden, the chairman of European Archaeology at Oxford, who later invited him to do a one-year master’s degree in archaeology at Oxford. That eventually led to a Ph.D. program after he spent some time in graduate school in the United States.

The current project began when he became fed up with the lack of ancient DNA evidence in papers about the origin of dogs. He called Dr. Dobney, of the University of Aberdeen in 2011, and said, “We’re doing dogs.”

After receiving the grant from the council in England, he and Dr. Dobney organized a conference in Aberdeen, Scotland, to gather as many people involved in researching dog origins as they could. His pitch to the group was that despite their different points of view, everyone was interested in the best possible evidence, no matter where it led.

“If we have to eat crow, we eat crow,” he said. “It’s science.”

A 32,000-Year-Old Skull

Mietje Germonpré, a paleontologist at the Royal Belgian Institute of Natural Sciences, is one of the many scientists participating in the dog project. She was one of a number of authors on a 2013 paper in Science that identified a skull about 32,000 years old from a Belgian cave in Goyet as an early dog. Dr. Wayne at U.C.L.A. was the senior author on the paper and Olaf Thalmann from the University of Turku in Finland was the first author.

It is typical of Dr. Larson’s dog project that although he disagreed with the findings of the paper, arguing that the evidence just wasn’t there to call the Goyet skull a dog, all of the authors of the paper are working on the larger project with him.

In November in Brussels, holding the priceless fossil, Dr. Germonpré pointed out the wide skull, crowded teeth and short snout of the ancient skull — all indicators to her that it was not a wolf.

“To me, it’s a dog,” she said. Studies of mitochondrial DNA, passed down from females only, also indicated the skull was not a wolf, according to the 2013 paper.

Dr. Germonpré said she thinks dogs were domesticated some time before this animal died, and she leans toward the idea that humans intentionally bred them from wolves.

She holds up another piece of evidence, a reconstruction of a 30,000-year-old canid skull found near Predmostí, in the Czech Republic, with a bone in its mouth. She reported in 2014 that this was a dog. And she says the bone is part of evidence the animal was buried with care. “We think it was deliberately put there,” she said.

But she recognizes these claims are controversial and is willing, like the rest of the world of canine science, to risk damage to the fossils themselves to get more information on not just the mitochondrial DNA but also the nuclear DNA.

To minimize that risk, she talked with Ardern Hulme-Beaman, a postdoctoral researcher with the Oxford team, about where to cut into it. He was nearing the end of months of traveling to Russia, Turkey, the United States and all over Europe to take samples of canid jaws and skulls.

He and Allowyn Evin, now with the National Center for Scientific Research in Montpelier, France, also took many photographs of each jaw and skull to do geometric morphometrics. Software processes detailed photographs from every angle into 3-D recreations that provide much more information on the shape of a bone than length and width measurements.

Dr. Germonpré and Dr. Hulme-Beaman agreed on a spot in the interior of the skull to cut. In the laboratory, he used a small electric drill with a cutting blade to remove a chunk the size of a bit of chopped walnut. An acrid, burning smell indicated that organic material was intact within the bone — a good sign for the potential retrieval of DNA.

Back in Oxford, researchers will attempt to use the most current techniques to get as much DNA as possible out of the sample. There is no stretch of code that says “wolf” or “dog,” any more than there is a single skull feature that defines a category. What geneticists try to establish is how different the DNA of one animal is from another. Adding ancient DNA gives many more points of reference over a long time span.

Dr. Larson hopes that he and his collaborators will be able to identify a section of DNA in some ancient wolves that was passed on to more doglike descendants and eventually to modern dogs. And he hopes they will be able to identify changes in the skulls or jaws of those wolves that show shifts to more doglike shapes, helping to narrow the origins of domestication.

The usual assumption about domestic animals is that the process of taming and breeding them happened once. But that’s not necessarily so. Dr. Larson and Dr. Dobney showed that pigs were domesticated twice, once in Anatolia and once in China. The same could be true of dogs.

Only the Beginning

Although the gathering of old bones is almost done, Dr. Larson is still negotiating with Chinese researchers for samples from that part of the world, which he says are necessary. But he hopes they will come.

If all goes well, said Dr. Larson, the project will publish a flagship paper from all of the participants describing their general findings. And over the next couple of years, researchers, all using the common data, will continue to publish separate findings.

Other large collaborative efforts are brewing, as well. Dr. Wayne, at U.C.L.A., said that a group in China was forming with the goal of sequencing 10,000 dog genomes. He and Dr. Larson are part of that group.

Last fall, Dr. Larson was becoming more excited with each new bit of data, but not yet ready to tip his hand about what conclusions the data may warrant, or how significant they will be.

But he is growing increasingly confident that they will find what they want, and come close to settling the thorny question of when and where the tearing power of a wolf jaw first gave way to the persuasive force of a nudge from a dog’s cold nose.

“I’m starting to drink my own Kool-Aid,” he said.

Ancient viral molecules essential for human development (Science Daily)

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Date: November 23, 2015

Source: Stanford University Medical Center

Summary: Genetic material from ancient viral infections is critical to human development, according to researchers.

Rendering of a virus among blood cells. Credit: © ysfylmz / Fotolia

Genetic material from ancient viral infections is critical to human development, according to researchers at the Stanford University School of Medicine.

They’ve identified several noncoding RNA molecules of viral origins that are necessary for a fertilized human egg to acquire the ability in early development to become all the cells and tissues of the body. Blocking the production of this RNA molecule stops development in its tracks, they found.

The discovery comes on the heels of a Stanford study earlier this year showing that early human embryos are packed full of what appear to be viral particles arising from similar left-behind genetic material.

“We’re starting to accumulate evidence that these viral sequences, which originally may have threatened the survival of our species, were co-opted by our genomes for their own benefit,” said Vittorio Sebastiano, PhD, an assistant professor of obstetrics and gynecology. “In this manner, they may even have contributed species-specific characteristics and fundamental cell processes, even in humans.”

Sebastiano is a co-lead and co-senior author of the study, which will be published online Nov. 23 in Nature Genetics. Postdoctoral scholar Jens Durruthy-Durruthy, PhD, is the other lead author. The other senior author of the paper is Renee Reijo Pera, PhD, a former professor of obstetrics and gynecology at Stanford who is now on the faculty of Montana State University.

Sebastiano and his colleagues were interested in learning how cells become pluripotent, or able to become any tissue in the body. A human egg becomes pluripotent after fertilization, for example. And scientists have learned how to induce other, fully developed human cells to become pluripotent by exposing them to proteins known to be present in the very early human embryo. But the nitty-gritty molecular details of this transformative process are not well understood in either case.

An ancient infection

The researchers knew that a type of RNA molecules called long-intergenic noncoding, or lincRNAs, have been implicated in many important biological processes, including the acquisition of pluripotency. These molecules are made from DNA in the genome, but they don’t go on to make proteins. Instead they function as RNA molecules to affect the expression of other genes.

Sebastiano and Durruthy-Durruthy used recently developed RNA sequencing techniques to examine which lincRNAs are highly expressed in human embryonic stem cells. Previously, this type of analysis was stymied by the fact that many of the molecules contain highly similar, very repetitive regions that are difficult to sequence accurately.

They identified more than 2,000 previously unknown RNA sequences, and found that 146 are specifically expressed in embryonic stem cells. They homed in on the 23 most highly expressed sequences, which they termed HPAT1-23, for further study. Thirteen of these, they found, were made up almost entirely of genetic material left behind after an eons-ago infection by a virus called HERV-H.

HERV-H is what’s known as a retrovirus. These viruses spread by inserting their genetic material into the genome of an infected cell. In this way, the virus can use the cell’s protein-making machinery to generate viral proteins for assembly into a new viral particle. That particle then goes on to infect other cells. If the infected cell is a sperm or an egg, the retroviral sequence can also be passed to future generations.

HIV is one common retrovirus that currently causes disease in humans. But our genomes are also littered with sequences left behind from long-ago retroviral infections. Unlike HIV, which can go on to infect new cells, these retroviral sequences are thought to be relatively inert; millions of years of evolution and accumulated mutations mean that few maintain the capacity to give instructions for functional proteins.

After identifying HPAT1-23 in embryonic stem cells, Sebastiano and his colleagues studied their expression in human blastocysts — the hollow clump of cells that arises from the egg in the first days after fertilization. They found that HPAT2, HPAT3 and HPAT5 were expressed only in the inner cell mass of the blastocyst, which becomes the developing fetus. Blocking their expression in one cell of a two-celled embryo stopped the affected cell from contributing to the embryo’s inner cell mass. Further studies showed that the expression of the three genes is also required for efficient reprogramming of adult cells into induced pluripotent stem cells.

Sequences found only in primates

“This is the first time that these virally derived RNA molecules have been shown to be directly involved with and necessary for vital steps of human development,” Sebastiano said. “What’s really interesting is that these sequences are found only in primates, raising the possibility that their function may have contributed to unique characteristics that distinguish humans from other animals.”

The researchers are continuing their studies of all the HPAT molecules. They’ve learned that HPAT-5 specifically affects pluripotency by interacting with and sequestering members of another family of RNAs involved in pluripotency called let-7.

“Previously retroviral elements were considered to be a class that all functioned in basically the same way,” said Durruthy-Durruthy. “Now we’re learning that they function as individual elements with very specific and important roles in our cells. It’s fascinating to imagine how, during the course of evolution, primates began to recycle these viral leftovers into something that’s beneficial and necessary to our development.”

Journal Reference:

  1. Jens Durruthy-Durruthy, Vittorio Sebastiano, Mark Wossidlo, Diana Cepeda, Jun Cui, Edward J Grow, Jonathan Davila, Moritz Mall, Wing H Wong, Joanna Wysocka, Kin Fai Au, Renee A Reijo Pera. The primate-specific noncoding RNA HPAT5 regulates pluripotency during human preimplantation development and nuclear reprogramming. Nature Genetics, 2015; DOI: 10.1038/ng.3449

Borboletas estão encolhendo por causa das mudanças climáticas (O Globo)

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Estudo mostra redução no tamanho de duas espécies na Groenlândia

POR O GLOBO

07/10/2015 15:57 / atualizado 07/10/2015 16:23

A Boloria chariclea foi uma das espécies analisadas pelos pesquisadores – Divulgação/Toke T. Hoye

RIO — As mudanças climáticas já provocam impactos sobre a Humanidade, mas também sobre algumas espécies animais. Um estudo publicado ontem na revista científica “Biology Letters” mostra que borboletas na Groenlândia se tornaram menores como resposta ao aumento das temperaturas. Para os pesquisadores, a mudança no tamanho corporal prejudica a mobilidade, que pode causar graves consequências à dinâmica populacional e distribuição geográfica das espécies.

Pesquisadores da Universidade de Aarhus, na Dinamarca, analisaram aproximadamente 4,5 mil borboletas de duas espécies diferentes capturadas entre 1996 e 2013. Os resultados apontaram para uma redução no tamanho das asas, na mesma taxa em ambas as espécies, provocada pelo aumento das temperaturas durante o verão. As espécies estudadas foram a Boloria chariclea e a Colias hecla.

— Nossos estudos mostram que machos e fêmeas seguem o mesmo padrão, que é similar em duas espécies diferentes, o que sugere que o clima exerce um papel importante na determinação do tamanho corporal das borboletas na Groenlândia — explicou Toke T. Hoye, pesquisador da Universidade de Aarhus.Esse é um dos primeiros estudos a acompanhar mudanças no tamanho corporal de uma espécie durante um período de mudanças climáticas, e corrobora pesquisas realizadas em laboratório, mas raramente demonstradas em campo.

A Colias hecla está ficando menor por causa dos verões mais quentes no Ártico – Divulgação/Toke T. Hoye

Experimentos apontam que a mudança no tamanho corporal é uma resposta antecipada às mudanças climáticas, que pode acontecer de duas maneiras. Para algumas espécies, uma temporada maior de alimentação pode resultar no aumento do tamanho, enquanto para outras, alterações metabólicas provocam a perda de energia e consequente redução das dimensões.

— Nós, humanos, usamos mais energia quando está frio, porque precisamos manter a temperatura corporal constante — disse Hoye. — Mas para a larva da borboleta e outros animais de sangue frio, que dependem do ambiente para manter a temperatura, o metabolismo aumenta em temperaturas maiores por causa dos processos bioquímicos que se tornam mais rápidos. Dessa maneira, a larva gasta mais energia do que é capaz de consumir. Nossos resultados indicam que essa mudança é tão significativa que a taxa de crescimento das larvas diminui. E quando as larvas são menores, as borboletas também se tornam menores.

As consequências para as borboletas do Ártico podem ser significativas. Com corpos menores, a mobilidade é reduzida. Como as duas espécies vivem apenas no Norte, a redução no tamanho pode ter graves consequências na dinâmica populacional, e prejudicar a dispersão dos insetos.

— Elas vivem tão ao Norte que não podem se mover para regiões mais frias, e elas provavelmente vão desaparecer da parte mais ao Sul da Groenlândia por causa do aumento da temperatura — disse Hoye. — Além disso, sua capacidade de dispersão está se deteriorando, e corpos menores devem resultar em menor taxa de fecundidade. Então, essas espécies do Ártico devem enfrentar desafios severos causados pela rápida mudança climática.

Leia mais sobre esse assunto em  http://oglobo.globo.com/sociedade/sustentabilidade/borboletas-estao-encolhendo-por-causa-das-mudancas-climaticas-17714284#ixzz3o0Y0gr6z
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Chimpanzés caçadores dão pistas sobre os primeiros humanos (El País)

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Primatas que usam lanças podem fornecer indícios sobre origem das sociedades humanas

 12 MAY 2015 – 18:14 BRT

Um velho chimpanzé bebe água em um lago, em Fongoli, no Senegal. / FRANS LANTING

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.

Os machos mais fortes dessa comunidade respeitam as fêmeas na caça

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%.

Uma fêmea de chimpanzé apanha e examina um galho que usará para capturar sua presa. / J. PRUETZ

“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.

Puppy-Dog Eyes of Science (Savage Minds)

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April 24, 2015 – John Hartigan

“Scientists say…” It’s interesting what natural science research starts making the rounds on social media. Mostly on diet or health broadly, and increasingly concerning climate change. On rare occasion—as over the past few days—some reports surface that offer insight into the circulating clutter itself, as in “cute dog” photos. In this instance, they’re opportunities to glimpse changing understandings of big topics, like domestication and evolution.

Links for two articles recently popped up in my Twitter feed: “The Science of Puppy-Dog Eyes” (NYTimes, 4/21/14) and “The Guilty Looking Companion,” Scientific American(4/20/15), both treating the gazing behavior of dogs and its various effects on humans. The first, by Jan Hoffman, reported on a study published in Science (in a themed-column on evolution), titled, “Dogs hijack the human bonding pathway.” The second, by Julie Hecht, “The Guilty Looking Companion,” builds off an article in Behavioral Processes, on a tangled question: “Are owners’ reports of their dogs’ ‘guilty look’ influenced by the dogs’ action and evidence of the misdeed?” Both suggest a far more agential companion species than many people might’ve suspected, but more importantly they each complicate stock domestication narratives suggesting it was something we simply did to them. They also suggest opportunities for extending social analysis beyond the human.

As the title of the Science article suggests, dogs were possibly canny drivers of domestication: “dogs became domesticated in part by adapting to human means of communication: eye contact.” In particular, the speculation is that dogs cleverly “utilized a natural system meant for bonding a parent with his or her child.” Evolutionarily, “the challenge for dogs may simply have been to express a behavioral (and morphological) repertoire that mimicked the cues that elicit caregiving toward our own young. Indeed, these juvenile characteristics of dogs are known to carry a selective advantage with respect to human preferences.” So dogs wile their way into our good graces by coopting the cuteness channel we have for children. To complicate agency a bit further, this seems to all hinge on a bidirectional hormonal mechanism: people and dogs both develop heightened, pleasurable levels of oxytocin from protracted gazing into each other’s eyes. “These findings suggest not only an interspecific effect of oxytocin, but also the exciting possibility of a feedback loop,” since “shifts in oxytocin concentration in a dog might elicit similar changes in a human and vice-versa—just as when a mother bonds with her infant.” Domestication just got a good deal more interesting.

“The guilty looking companion” takes up the theme of sociality and how social bonds are respectively maintained in various species, but also how humans might be duped by our tendency to anthropomorphize dogs as possessing a subjective state approximating shame. The reparative behaviors of appeasement and reconciliation that maintain relationships, practiced by many species, when manifested by dogs, reads easily, to us, as “guilt.” But through a fascinating series of experiments, researchers countered that these canine gestures are just “cohesive displays,” which operate “to reduce conflict, diffuse tension, and reinforce social bonds.” Dogs are not responding to ameliorating a subjective sense of shame at transgressing rules; they are instead “incredibly sensitive to environmental and social cues.” If there’s furniture torn or overturned, the owner is looking for someone to chastise—better grovel or cringe. These behavior are very effective, according to surveys of dog owners, who withhold punishments in the wake of such displays. But Hecht concludes with a caution: “It might just be that we’re anthropomorphizing,” in reference to the viral spew of “dog shamming” photos. “Which, in this case, might not be good for us or our dogs.” Indeed, but what is even more valuable here is the perspective opened up onto thinking about parallel and converging forms of species sociality, beyond the question of who is domesticating who.

On that topic, another recently published science article pursues just these openings, though unfortunately it does not seem to be circulating widely at all. “Testing the myth: Tolerant dogs and aggressive wolves,” in Proceedings B (Royal Society Publishing) reports on findings that indicate “a steeper dominance hierarchy in dogs than in wolves.” While “tolerance” is supposed to be the character trait “selected for,” dogs appear far more aggressive and uncooperative with conspecifics than wolves. The problem with “all domestication theories” to date is that they’ve ignored “apparently contradictory behaviours…observed in dogs and wolf packs.” There’s an enormous amount to this piece, but it may come down to “face,” as Erving Goffman developed the concept. “Visual communication in dogs is somewhat impaired due to their reduced visual (facial as well as bodily) expressions,” which “might lead to an inability to control conflicts in close quarters.” Wolves are far more articulate in reading both gaze and facial features in conspecific communications. Range et al write, “Although dogs and wolves seem to use the same signals overall, it is possible that dogs do not use them as appropriately as wolves”—i.e., they haven’t refined the etiquette of conspecific communications quite as well, though they’re very good at circumventing our conspecific gaze signaling tendencies.

But that “wolves appear tolerant, attentive, and at the same time cooperative towards pack members” is in stark “contrast to the starting point of several recent domestication hypotheses.” Free-ranging dogs—constituting about 76-83% of the global dog population!!—not so much. So the questions swirl as to dogs’ cognitive and emotional processes underlying their intraspecific sociality and how that variously aligns with ours, in the deep past and today.

“Nobres Selvagens” na Ilustríssima (Folha de S.Paulo) de domingo, 22 de fevereiro de 2015

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Antropólogos, índios e outros selvagens

RICARDO MIOTO
ilustração ANA PRATA

22/02/2015  03h05

RESUMO Livro do antropólogo Napoleon Chagnon que aborda suas pesquisas entre os ianomâmis é lançado no Brasil. Em entrevista, autor, que direcionou sua carreira para uma interpretação evolutiva do comportamento indígena, fala sobre suas conclusões e comenta a recepção, muitas vezes negativa, de sua obra entre seus pares.

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Sobre Napoleon Chagnon, 76, há só uma unanimidade: trata-se do pesquisador mais polêmico da antropologia contemporânea.É

Nesta entrevista, o americano –que lança agora no Brasil o livro “Nobres Selvagens: Minha Vida entre Duas Tribos Perigosas: os Ianomâmis e os Antropólogos” pelo selo Três Estrelas, do Grupo Folha– afirma que a antropologia brasileira representa o que há de mais atrasado no pensamento anticientífico nessa área.

Chagnon critica ainda alguns brasileiros ligados à temática indígena, como o líder ianomâmi Davi Kopenawa, “manipulado por antropólogos e ONGs”, e o cineasta José Padilha, autor do documentário “Segredos da Tribo”, que “deveria se limitar a filmar Robocop”.

Ana Prata

Chagnon estudou os ianomâmis do Brasil e, principalmente, da Venezuela a partir de 1964 e ao longo de 35 anos, em 25 viagens que totalizaram 5 anos entre os índios. Foi o pioneiro no contato com várias tribos isoladas, que acredita serem uma janela para as sociedades pré-históricas nas quais o gênero Homo viveu por milhões de anos.

Foi visto com antipatia por diversos colegas antropólogos por propor explicações darwinianas para o comportamento dos índios –e dos humanos em geral– e ao escrever, em 1968, um livro em que tratava amplamente da violência entre os índios e no qual, desde o título, “Yanomamö: The Fierce People” (sem tradução no Brasil), chamava os ianomâmis de “o povo feroz”. Despertou inimizades ao se afastar dos colegas antropólogos, que acreditava mais interessados em fazer política do que ciência, e se aproximar de geneticistas.

Foi em 1988, porém, que causou a fúria dos colegas, ao publicar na revista “Science” um estudo mostrando que os homens ianomâmis com assassinatos no currículo eram justamente os que tinham mais mulheres e descendentes. Em termos biológicos, a violência masculina e certo egoísmo humano seriam estratégias reprodutivas bem-sucedidas, ideia que desagradou fortemente seus colegas das humanidades.

O antropólogo sempre defendeu que os índios que estudou guerreavam movidos por uma insaciável vontade de capturar mulheres, enquanto os livros tradicionais de antropologia diziam que a guerra primitiva tinha motivos como a escassez de alimentos ou de terra.

Chagnon diz que seus críticos são marxistas movidos pela ideologia de que os conflitos humanos se explicam pela luta de classes ou por disputas materiais, e não por motivos mais animalescos, como a busca por sucesso sexual.

Ele afirma que nenhum colega pôde apontar falhas nos dados publicados na “Science”. No entanto, antropólogos questionam seu procedimento não só nesse caso como em outros trabalhos (leia ao lado).

Em 2000, o jornalista Patrick Tierney publicou o livro “Trevas no Eldorado” (lançado no Brasil em 2002, pela Ediouro), acusando Chagnon e colegas, entre outras coisas, de terem espalhado sarampo deliberadamente entre os índios. As acusações foram investigadas pela Associação Americana de Antropologia, que inocentou os pesquisadores da grave acusação.

Na entrevista abaixo, feita por telefone, Chagnon trata ainda de temas como a higiene dos índios e os riscos da selva.

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Folha – O antropólogo Eduardo Viveiros de Castro criticou na internet a publicação do seu livro no Brasil, dizendo que o sr. está ligado à “direita boçalmente cientificista”.

Napoleon Chagnon – A ideia de que o comportamento humano tem uma natureza biológica, moldada pela evolução, além da cultura, sofreu muita oposição nas últimas décadas de quem tem uma visão marxista. Está havendo uma mudança de paradigma, mas os antropólogos brasileiros são o último reduto dessa oposição e sempre tentaram impedir meu trabalho.

Marxistas não gostam de explicações que não envolvam a luta por recursos materiais. Para eles, isso explica tudo. Eles diziam, por exemplo, que a causa da guerra entre os ianomâmis era a escassez de proteína –uma tribo atacaria a outra em busca de carne. Nossas observações mostraram, porém, que não havia correlação. Eles tinham abundância de proteína; lutavam, na verdade, por mulheres.

Nos EUA, cientistas importantes, como meu grande amigo Steven Pinker e o professor Jared Diamond, escreveram recentemente livros demonstrando a relevância crescente da psicologia evolutiva.

Os antropólogos latino-americanos me atacam, mas não têm dados para rebater as conclusões que proponho, porque não gostam de trabalho de campo. Eles gostam de argumentos teóricos, de ficar sentados nas suas cadeiras na universidade fazendo ativismo. No entanto, para entender o mundo, você tem de coletar informações a fim de testar suas previsões e teorias. Essa é a base do método científico. A tendência pós-modernista é dizer que não há verdade, que tudo é social ou político. Isso é a morte da ciência.

Esses críticos dizem que sua visão dos ianomâmis é muito negativa. Citam trechos do seu livro em que o sr. descreve criticamente os hábitos de higiene dos índios, dizendo que eles espalhavam muco em tudo.

Tenho muitas críticas à minha própria civilização também, como o excesso de filas. Os ianomâmis não têm uma teoria da transmissão de doenças via germes. Então assoam o nariz na mão e passam no cabelo, nos outros, até na minha bermuda [risos]. A primeira coisa que quis aprender na língua deles foi “não encoste em mim, suas mãos estão sujas”, mas não adiantou. Você se acostuma.

Na verdade, você percebe que há coisas mais sérias com que se preocupar. A vida na tribo é perigosa. Há muitas cobras. Um bebê de uma tribo ianomâmi em que vivi sumiu, e os pais concluíram que a única explicação era que tivesse sido comido por uma anaconda. Há ainda muitos insetos, há onças, muitos outros incômodos.

Como é a sua relação com o líder ianomâmi Davi Kopenawa?

Ele é manipulado pelos seus mentores, seus conselheiros políticos, a maioria antropólogos e ONGs, que dizem a ele o que ele deve declarar. Ouço que muitos jornalistas brasileiros têm essa percepção, mas sabem que é impopular dizer isso em público.

As entrevistas com ele costumam ser mediadas por antropólogos.

Pois é. Veja, em uma das minhas visitas aos ianomâmis no Brasil, Kopenawa proibiu o piloto do meu avião de utilizar o combustível que tinha guardado perto de uma das tribos em que ele tinha influência. Ele queria a todo custo que eu ficasse isolado na floresta, fez isso deliberadamente. O piloto teve de conseguir combustível com outros colegas. Essa é uma das razões que me levaram a não ter uma opinião muito positiva a respeito dele.

Kopenawa critica vocês por não devolverem amostras de sangue que coletaram entre os índios em 1967 para estudos científicos na área de genética e que foram parar em bancos de universidades dos EUA.

Sou simpático a esse pedido. Mas essas amostras são 99% de tribos venezuelanas, não brasileiras. Seria horrível se entregássemos tal sangue para os ianomâmis brasileiros, como Kopenawa. Uma tribo ficaria muito assustada de saber que seus vizinhos têm o sangue de seus ancestrais, eles acreditam que isso poderia ser utilizado para fazer magia negra, por exemplo.

É importante dizer que, influenciadas por antropólogos, lideranças ianomâmis tornaram impossível hoje, para qualquer pesquisador, ir a suas tribos e coletar amostras de sangue; foram convencidos de que isso foi um crime terrível que cometemos. Dessa forma, nenhum pesquisador da área biomédica pode agora fazer estudos que envolvam coleta de amostras. Os ianomâmis vetaram para sempre qualquer pesquisa que possa beneficiar a sua saúde e dependa de exames de sangue.

Eu gosto muito dos ianomâmis. Fiquei muitos anos com eles. Eles merecem ser mais bem representados. É nítido que eles precisam de instituições que permitam acesso à medicina moderna, por exemplo. Eles precisam de ajuda.

De qualquer forma, eu não coletei amostras de sangue. Eu só ajudei os médicos a fazê-lo. Eu sou antropólogo. Não estou nem aí para o que acontecerá com as amostras de sangue congeladas nos EUA. Mas seria irresponsável se fossem entregues aos índios errados.

O sr. assistiu ao documentário “Os Segredos da Tribo” (2010), do brasileiro José Padilha?

Padilha mentiu para mim, foi muito desonesto. Ele disse que faria um filme equilibrado, mas nunca mencionou que as acusações feitas contra mim foram completamente desmentidas [pela Associação Americana de Antropologia]. Ele contratou um missionário que falava a língua ianomâmi para fazer as entrevistas com os índios. Esse missionário, amigo meu, depois veio me avisar que Padilha direcionava as entrevistas contra mim, que tudo era feito para criar a impressão de que os ianomâmis me odiavam. O filme é ridículo.

Além disso, Padilha lançou o filme e desapareceu, nunca respondeu às minhas ligações. Na apresentação do filme no festival de Sundance, ele não só não me convidou como chamou três antropólogos inimigos meus para debater. Um deles, Terence Turner, que teve participação ativa na elaboração do filme, me acusava de ser o Mengele das tribos ianomâmis. É doentio. Padilha deveria se limitar a filmar “Robocop”.

Depois de trabalhar muitos anos nas universidades do Michigan e de Missouri, o sr. agora é professor aposentado. Aposentou-se também da pesquisa científica?

Não. Continuo trabalhando com os dados que coletei nas tribos ao longo desses anos todos. Estou para publicar vários artigos em revistas importantes, como a “Science”, mostrando o impacto de conceitos caros à biologia, como o parentesco, na organização das tribos ianomâmis. Se os antropólogos brasileiros não gostam do meu trabalho, ainda não viram nada [risos]. No caso do público brasileiro, espero que os leitores encontrem no meu livro agora publicado uma melhor compreensão da natureza humana, seja no comportamento dos povos indígenas ou no de um vizinho.

RICARDO MIOTO, 25, é editor de “Ciência” e “Saúde” da Folha.

ANA PRATA, 34, é artista plástica.

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Livro contribui para distanciar ciências humanas e biológicas

André Strauss

22/02/2015  03h09

Por sua alegada coragem em sustentar hipóteses fundamentadas em princípios darwinianos, o antropólogo americano Napoleon Chagnon, que dedicou sua carreira a estudar a violência entre os índios ianomâmis, apresenta-se em “Nobres Selvagens” [trad. Isa Mara Lando, Três Estrelas, 608 págs., R$ 89,90] como vítima dos mais diversos ataques e preconceitos por parte de seus pares.

Os antropólogos culturais, os religiosos salesianos, os ativistas políticos e os próprios ianomâmis são retratados como grupos ferozes ou biofóbicos. Já Chagnon seria apenas um inocente antropólogo de Michigan. A tese não convence.

Embora o antropólogo pretenda ser um expoente da síntese entre biologia e antropologia, suas proposições são bastante limitadas e, muitas vezes, equivocadas. Exemplo disso é partir do princípio de que uma sociedade não contatada é o mesmo que uma sociedade não impactada, atribuindo aos ianomâmis condição análoga à de sociedades paleolíticas. Propor um contratualismo hobbesiano baseado na luta por mulheres também soa ingênuo.

Em seu livro, Napoleon Chagnon insiste na noção anacrônica de “ciência pura”, desmerecendo a militância pró-indígena dos antropólogos brasileiros como um capricho do politicamente correto.

Mesmo reconhecendo-se que em diversas ocasiões seus detratores exageraram, esse tipo de postura maniqueísta do autor não contribui para a necessária superação dos conflitos epistemológicos e políticos que seguem existindo, ainda que ligeiramente mitigados, entre as chamadas ciências humanas e biológicas.

Um famoso filósofo darwiniano certa vez reconheceu que as teorias antropológicas de cunho biológico têm, inegavelmente, o péssimo hábito de atrair os mais indesejáveis colaboradores. Daí a importância da cada vez maior politização dos bioantropólogos e o movimento explícito por parte deles para impedir que esses associados participem de seus círculos.

Ainda assim, provavelmente Chagnon não é culpado das acusações mais graves que lhe foram imputadas, tal como a de disseminar propositalmente uma epidemia de sarampo entre os indígenas ou a de incentivar, por escambo, que eles declarassem guerras uns contra os outros a fim de que ele pudesse incluir as cenas de violência em um documentário que estava produzindo.

Por outro lado –e isso não se pode negar a Chagnon–, é verdade que as humanidades muitas vezes parecem apresentar aquilo que se convencionou chamar de um “desejo irresistível para a incompreensão”, resultando em acusações injustas e de caráter persecutório.

Algumas décadas atrás, ainda era possível negar a relevância de campos como a genética comportamental, a ecologia humana, a neurociência cognitiva ou a etologia de grandes símios. Atualmente, entretanto, qualquer tentativa de mantê-los fora da esfera antropológica é um exercício vão.

Mais importante, a estratégia comumente utilizada no passado de atrelar os desdobramentos oriundos dessas áreas a implicações nefastas para a dignidade humana, torna-se, além de injusta, muito perigosa.

Juntos, antropólogos e biólogos precisam elaborar uma narrativa capaz de ressignificar esses novos elementos através de uma ótica benigna. Afinal, eles passarão, inevitavelmente, a fazer parte do arcabouço teórico de ambas as disciplinas.

ANDRÉ STRAUSS, 30, é antropólogo do Laboratório de Estudos Evolutivos Humanos da USP e do Instituto Max Planck de Antropologia Evolutiva, na Alemanha.

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Trajetória do pesquisador é marcada por querelas

Marcelo Leite

22/02/2015  03h13

Não é trivial resumir as objeções que a antropologia cultural levanta contra Napoleon Chagnon. A controvérsia tem quase meio século, e a tarefa fica mais complicada quando muitos dos antropólogos relevantes do Brasil se recusam a dar entrevistas sobre o caso.

O panorama se turvou de vez em 2000, com o livro “Trevas no Eldorado”. Nele o jornalista Patrick Tierney acusava Chagnon e o médico James Neel de, em 1968, terem causado uma epidemia de sarampo entre os ianomâmis da Venezuela e experimentado nos índios um tipo perigoso de vacina, além de negar-lhes socorro médico.

Chagnon e Neel foram depois inocentados dessas acusações graves. Bruce Albert, antropólogo e crítico de Chagnon que trabalha há 36 anos com os ianomâmis, já escreveu sobre a ausência de fundamento das alegações de Tierney.

Ana Prata

Nem por isso Albert deixa de assinalar sérios erros éticos da dupla. Para ele, os ianomâmis foram usados, sem saber, como grupo de controle para estudos sobre efeitos de radiação nuclear no sangue de sobreviventes de bombardeios em Hiroshima e Nagasaki.

Chagnon, capataz de Neel na expedição, obtinha amostras de sangue em troca de machados, facões e panelas. Embora essa prática perdurasse nos anos 1960-70, Albert ressalva que regras exigindo consentimento informado já vigiam desde 1947 (Código de Nuremberg) e 1964 (Declaração de Helsinque).

Os reparos ao trabalho de Chagnon abarcam também a própria ciência. Ele se diz superior aos antropólogos tradicionais, que acusa de relativistas pós-modernos, xingamento comum nos setores cientificistas da academia americana.

A polêmica teve início com o livro “Yanomamö: The Fierce People”, em que Chagnon apresentou sua tese de que ianomâmis são uma relíquia ancestral da espécie humana: selvagens com compulsão pela guerra como forma de obter mulheres, escassas devido à prática do infanticídio feminino.

Os críticos da etnografia de Chagnon afirmam que ele nunca comprovou o infanticídio seletivo. Com efeito, a explicação foi abandonada em outros estudos, como um famigerado artigo de 1988 no periódico científico “Science”.

O trabalho recorre a dados demográficos coletados por Chagnon para corroborar sua noção, bem ao gosto da sociobiologia, de que os homens mais violentos eram os que tinham mais mulheres e filhos. Esses seriam os que os ianomâmis chamam “unokai” –segundo o autor, os mais temidos no grupo (e, por isso, mais prolíficos).

Albert, Jacques Lizot e outros antropólogos consideram que ele misturou alhos com bugalhos. “Unokai” não seria um atributo individual, mas o estado de impureza (simbólica) daquele que mata alguém com armas ou feitiçaria, ou mesmo só entra em contato com o sangue de cadáveres de inimigos.

Além disso, em incursões contra outras aldeias, os guerreiros muitas vezes dão golpes e flechadas em adversários já mortos. Isso os tornaria “unokai”, não homicidas.

Os mais admirados não seriam esses, mas os “waitheri”, algo como “valorosos”, que se distinguem não só pela valentia, mas também pela capacidade de liderar, de falar bem, até pelo humor.

Não bastasse isso, os críticos apontam manipulação de números. Para inflar seus dados e chegar a 44% de homens que teriam participado de mortes e tinham até o triplo de filhos na comparação com os não “unokai”, Chagnon teria excluído da amostra jovens de 20 a 25 anos e homens mortos –violentos ou não, com ou sem filhos.

Em fevereiro de 2013, o antropólogo Marshall Sahlins renunciou à Academia Nacional de Ciências dos EUA após o ingresso de Chagnon. Num artigo em que explicava o ato, defendeu que um antropólogo alcança entendimento superior de outros povos quando toma seus integrantes como semelhantes –e não objetos naturais, “selvagens”, ao modo de Chagnon.

“É claro que esse não é o único meio de conhecer os outros. Podemos também utilizar nossa capacidade simbólica para tratá-los como objetos físicos”, escreveu. “Mas não obteremos o mesmo conhecimento dos modos simbolicamente ordenados da vida humana, do que é a cultura, ou até a mesma certeza empírica.”

MARCELO LEITE, 57, é repórter especial e colunista da Folha.

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Morte sistemática de Ianomâmis é um tabu

Leão Serva

23/02/2015  02h00

A Folha publicou com grande destaque na edição de domingo (22) a notícia do lançamento do livro “Nobres Selvagens” (pela Três Estrelas, selo do Grupo Folha), de autoria do antropólogo norte-americano Napoleon Chagnon. Títulos na capa e no caderno da Ilustríssima chamaram a obra de “livro tabu”.

Trata-se de um exagero baseado no discurso persecutório do autor, que sempre responde às críticas a seu trabalho com alegações de perseguição pessoal ou boicote. Uma pesquisa no Google News apresenta 872 respostas com notícias sobre o antropólogo e 64 referências ao livro, incluindo veículos de grande prestígio internacional como “The New York Times” e “Washington Post”.

No Brasil, certamente a obra não foi tema de reportagens simplesmente porque não havia sido lançada.

Na edição, textos de Marcelo Leite e André Strauss compilam as principais fragilidades apontadas pelos críticos da obra de Chagnon.

Uma bem importante, no entanto, não foi mencionada: o antropólogo dá pouca importância ao caráter simbólico das expressões da cultura que aparecem nos depoimentos de índios (e de brancos também, é bom que se diga), o que o leva a tomar o que ouve literalmente. Assim, em sua entrevista, é quase infantil a descrição dos perigos de uma aldeia Ianomâmi. Os medos que Chagnon menciona que concentrariam a atenção dos índios para longe dos cuidados médicos (risco de onças e cobras) são próprios de um alienígena. Já os índios criam cobras em casa para comer ratos; sabem que onças têm medo dos homens e, em situações raras, quando se aproximam furtivamente da periferia da aldeia para tocaiar uma criança, logo são capturadas pelos índios, como eu mesmo testemunhei. Não quer dizer que não haja medo, mas o antropólogo o amplifica para reforçar o estereótipo de atraso.

A história de que um casal ianomâmi teria atribuído o desaparecimento de seu filhinho a uma anaconda esfomeada é bizarra: o bebê na aldeia não fica um minuto longe dos outros e uma sucuri no lento processo de engolir uma criança seria vista por dúzias de pessoas e morta. Chagnon certamente não entendeu o que lhe foi dito ou tomou por verdade uma mentira (vale lembrar que um “civilizado” banqueiro suíço também mente).

Em texto mais antigo, Chagnon apontava o gesto de bater no peito, comum em festas de ianomâmis como expressão da violência da cultura desses grupos. Ora, o mesmo movimento pode ser encontrado diariamente em culturas mais “evoluídas”, segundo seu critério, das grandes cidades da Europa e dos EUA (nas missas católicas quando se diz “Minha culpa, minha culpa, minha máxima culpa”) à Mesopotâmia, berço das civilizações (onde soldados contemporâneos reproduzem o gesto antes de ataques de infantaria). Chagnon não leva em conta o alicerce básico do estudo da antropologia, que as culturas humanas são simultâneas, embora diferentes na expressão material.

Por fim, para desfazer as críticas feitas pelo líder Davi Kopenawa, criou a história de que ele é manipulado por antropólogos. A Folha parte dessa premissa para questionar Chagnon: “As entrevistas com ele costumam ser mediadas por antropólogos”, ao que o autor diz: “Pois é”, e segue sua catilinária.

Trata-se de uma inverdade que qualquer repórter que fale bem português ou ianomâmi pode comprovar. Eu entrevistei Kopenawa três vezes em épocas e lugares diferentes, duas delas sem aviso prévio. Me aproximei, pedi para falar e conversamos sem mediação. Uma vez, em seu escritório em Boa Vista, ele pediu que outras pessoas (que eu não conhecia, índios e brancos) saíssem da sala para ser entrevistado. Fala fluentemente um português simples (de brasileiro não universitário) com forte sotaque. É preciso ter calma e prestar atenção, por vezes pedir que repita para entender a pronúncia de algumas palavras.

A última vez que o encontrei foi numa entrevista para a revista Serafina, com hora marcada. Também ficou só, enquanto eu estava acompanhado da jovem fotógrafa Helena Wolfenson, da Folha. É possível que estrangeiros que falem mal ou não falem português precisem de tradutor. E são certamente raras as pessoas que falam português, ianomâmi e línguas estrangeiras. Talvez daí a história de que ele se faça acompanhar de “antropólogos” ou gente de ONG.

*

O que de fato é um “tabu” (aquilo de que não se fala) na imprensa brasileira é o lento processo de abandono dos Ianomâmi à morte, em curso por incompetência ou (depois de tanto tempo) decisão do governo federal.

Como noticiei nesta coluna em maio do ano passado, as mortes de Ianomâmi por problemas de saúde cresceram nos dois governos do PT (Lula e Dilma). Muitas das doenças são simples de evitar, como provam as estatísticas da segunda metade dos anos 1990.

O aumento se deve em grande medida à interrupção dos trabalhos de medicina preventiva nas aldeias e ao crescimento dos gastos com transporte dos doentes das aldeias para a capital de Roraima, Boa Vista.

A maior parte dos custos do Ministério da Saúde com a saúde indígena em Roraima tem sido despejada em frete de aviões para levar índios a Boa Vista. São poucas as empresas de táxi aéreo, as mesmas que levam políticos locais em seus deslocamentos.

Em janeiro do ano passado, quando a entrevistei, a coordenadora do Ministério da Saúde para as áreas indígenas de Roraima, Maria de Jesus do Nascimento, explicou o aumento das mortes dizendo: “Não, dinheiro não falta… Foi problema de gestão, mesmo”.

Na área Ianomâmi, uma médica cubana do programa Mais Médicos se desesperava: “Não tenho antibióticos, não tenho oxigênio, não tenho equipamentos”. Eu perguntei o que fazia: “Não quero mas sou forçada a mandar os índios de avião para Boa Vista”. O meio se tornou o fim. A saúde dos índios se tornou desculpa para enriquecer as empresas de táxi aéreo.

Quem procura no mesmo Google News notícias sobre as mortes de Ianomâmi pela improbidade dos órgãos de saúde local só encontra quatro notícias, uma delas do espanhol El País, as demais noticiando os protestos dos índios e um debate no Congresso.

Esse genocídio lento e discreto é o verdadeiro tabu.

Stone Age humans weren’t necessarily more advanced than Neanderthals (Science Daily)

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Date: January 14, 2015

Source: Universite de Montreal

Summary: A multi-purpose bone tool dating from the Neanderthal era has been discovered by researchers, throwing into question our current understanding of the evolution of human behavior. It was found at an archaeological site in France.

The tool in question was uncovered in June 2014 during the annual digs at the Grotte du Bison at Arcy-sur-Cure in Burgundy, France. Extremely well preserved, the tool comes from the left femur of an adult reindeer and its age is estimated between 55,000 and 60,000 years ago. Marks observed on it allow us to trace its history. Obtaining bones for the manufacture of tools was not the primary motivation for Neanderthals hunting — above all, they hunted to obtain the rich energy provided by meat and marrow. Evidence of meat butchering and bone fracturing to extract marrow are evident on the tool. Percussion marks suggest the use of the bone fragment for carved sharpening the cutting edges of stone tools. Finally, chipping and a significant polish show the use of the bone as a scraper. Credit: University of Montreal – Luc Doyon

A multi-purpose bone tool dating from the Neanderthal era has been discovered by University of Montreal researchers, throwing into question our current understanding of the evolution of human behaviour. It was found at an archaeological site in France. “This is the first time a multi-purpose bone tool from this period has been discovered. It proves that Neanderthals were able to understand the mechanical properties of bone and knew how to use it to make tools, abilities usually attributed to our species, Homo sapiens,” said Luc Doyon of the university’s Department of Anthropology, who participated in the digs. Neanderthals lived in Europe and western Asia in the Middle Paleolithic between around 250,000 to 28,000 years ago. Homo sapiens is the scientific term for modern man.

The production of bone tools by Neanderthals is open to debate. For much of the twentieth century, prehistoric experts were reluctant to recognize the ability of this species to incorporate materials like bone into their technological know-how and likewise their ability to master the techniques needed to work bone. However, over the past two decades, many clues indicate the use of hard materials from animals by Neanderthals. “Our discovery is an additional indicator of bone work by Neanderthals and helps put into question the linear view of the evolution of human behaviour,” Doyon said.

The tool in question was uncovered in June 2014 during the annual digs at the Grotte du Bison at Arcy-sur-Cure in Burgundy, France. Extremely well preserved, the tool comes from the left femur of an adult reindeer and its age is estimated between 55,000 and 60,000 years ago. Marks observed on it allow us to trace its history. Obtaining bones for the manufacture of tools was not the primary motivation for Neanderthals hunting — above all, they hunted to obtain the rich energy provided by meat and marrow. Evidence of meat butchering and bone fracturing to extract marrow are evident on the tool. Percussion marks suggest the use of the bone fragment for carved sharpening the cutting edges of stone tools. Finally, chipping and a significant polish show the use of the bone as a scraper.

“The presence of this tool at a context where stone tools are abundant suggests an opportunistic choice of the bone fragment and its intentional modification into a tool by Neanderthals,” Doyon said. “It was long thought that before Homo sapiens, other species did not have the cognitive ability to produce this type of artefact. This discovery reduces the presumed gap between the two species and prevents us from saying that one was technically superior to the other.”

Luc Doyon, Geneviève Pothier Bouchard, and Maurice Hardy published the article “Un outil en os à usages multiples dans un contexte moustérien,” on December 15, 2014 in the Bulletin de la Société préhistorique française. Luc Doyon and Geneviève Potheir Bouchard are affiliated with the Department of Anthropology of the Université de Montréal. Maurice Hardy, who led the archaeological digs at the Grotte du Bison, is affiliated with Université Paris X — Nanterre.

Archaeologists unearth 5,000-year-old ‘third-gender’ caveman (Mother Nature Network)

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Caveman was buried like a woman, leading scientists to question his sexual orientation.

By: Bryan Nelson

Fri, Apr 08, 2011 at 05:47 AM

Photo: ZUMA Press

Archaeologists investigating a 5,000-year-old Copper Age grave in the Czech Republic believe they may have unearthed the first known remains of a gay or transvestite caveman, reports the Telegraph.
The man was apparently buried as if he were a woman, an aberrant practice for an ancient culture known for its strict burial procedures.
Since the grave dates to between 2900 and 2500 BC, the man would have been a member of the Corded Ware culture, a late Stone Age and Copper Age people named after the unique kind of pottery they produced. Men in this culture were traditionally buried lying on their right side with their heads pointing west, but this man was instead buried on his left side with his head pointing east, which is how women were typically buried.
“From history and ethnology, we know that people from this period took funeral rites very seriously so it is highly unlikely that this positioning was a mistake,” said lead archaeologist Kamila Remisova Vesinova. “Far more likely is that he was a man with a different sexual orientation, homosexual or transsexual.”
Another clue is that Corded Ware men would typically be buried alongside weapons, hammers and flint knives, as well as food and drink to prepare them for their journey to the other side. But this man’s grave instead contained only a traditional egg-shaped pot, which was what women were typically buried with.
With all the evidence taken together, archaeologists are confident that the best explanation for the strange burial is that the man was effeminate, perhaps a homosexual, and possibly a transvestite.
“We believe this is one of the earliest cases of what could be described as a ‘transsexual’ or ‘third gender grave’ in the Czech Republic,” reiterated cooperating archaeologist Katerina Semradova.
Semradova also noted that archaeologists from a previous dig had uncovered a grave from the Mesolithic period where a female warrior was buried as a man, so mixed gender burials, though rare, were not unprecedented.

Read more: http://www.mnn.com/lifestyle/arts-culture/stories/archaeologists-unearth-5000-year-old-third-gender-caveman?utm_content=buffer6fa50&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer#ixzz3KOhZ8gxq

Epigenetics

Uncategorized, , ,

Transgenerational effects of prenatal exposure to the 1944–45 Dutch famine – BJOG: An International Journal of Obstetrics & Gynaecology

Volume 120, Issue 5, pages 548–554, April 2013

MVE Veenendaal et al.

DOI: 10.1111/1471-0528.12136

http://onlinelibrary.wiley.com/doi/10.1111/1471-0528.12136/full

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Mothers’ stress during 1998 ice storm shows up in children’s DNA, study says (Fox News)

By John Johnson

Published October 20, 2014

Mothers' stress during 1998 ice storm shows up in children's DNA: study

File photo of the aftermath of an ice storm. (AP Photo/Matt Rourke)

Just how bad was an epic 1998 ice storm in Canada? You can read all about it in the DNA of kids who were born around that time.

An intriguing study in PLoS One finds that women who were especially stressed during the storm gave birth to kids whose immune cells have telltale signs of their mothers’ trouble, reports Raw Story.

The storm was brutal, leaving people without power for more than a month. Researchers at the time surveyed expectant moms to gauge their “objective” distress, measuring things such as how many days they went without electricity.

Then they tracked down their kids more than a decade later and found that moms who were in the most distress bore children whose DNA had specific markers as a result.

The genes affected are related to immune function and sugar metabolism. Toronto’s Globe and Mail has a nice explanation of what’s going on, with help from Suzanne King of McGill University.

It involves “epigenetics,” as opposed to genetics:

  • “An individual’s genetics are like a musical score, and what’s written comes from the mother and father. … Although nothing can change what’s written on the page, environmental factors act as an orchestral conductor might, amplifying some aspects and tempering others, leaving markings, or methylation of the DNA.”

This isn’t necessarily a bad thing.

A pregnant woman in a famine, for instance, might “amplify” traits that would give her child a better chance of surviving—traits that could then backfire in terms of health if the famine goes away.

It’s not clear what, if any, health effects the Canadian kids will see as a result, explains a post at McGill University. But given the genes affected, they might have a greater risk of developing asthma, diabetes, or obesity.

(You can blame your coffee craving on DNA, too.)

This article originally appeared on Newser: Moms’ Stress in Ice Storm Shows Up in Kids’ DNA

Neandertal trait in early human skull suggests that modern humans emerged from complex labyrinth of biology and peoples (Science Daily)

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Date: July 7, 2014

Source: Washington University in St. Louis

Summary: Re-examination of a circa 100,000-year-old archaic early human skull found 35 years ago in Northern China has revealed the surprising presence of an inner-ear formation long thought to occur only in Neandertals.

The Xujiayao 15 late archaic human temporal bone from northern China with the extracted temporal labyrinth superimposed on a view of the Xujiayao site. Credit: Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Science

Re-examination of a circa 100,000-year-old archaic early human skull found 35 years ago in Northern China has revealed the surprising presence of an inner-ear formation long thought to occur only in Neandertals.

“The discovery places into question a whole suite of scenarios of later Pleistocene human population dispersals and interconnections based on tracing isolated anatomical or genetic features in fragmentary fossils,” said study co-author Erik Trinkaus, PhD, a physical anthropology professor at Washington University in St. Louis.

“It suggests, instead, that the later phases of human evolution were more of a labyrinth of biology and peoples than simple lines on maps would suggest.”

The study, forthcoming in the Proceedings of the National Academy of Sciences, is based on recent micro-CT scans revealing the interior configuration of a temporal bone in a fossilized human skull found during 1970s excavations at the Xujiayao site in China’s Nihewan Basin.

Trinkaus, the Mary Tileston Hemenway Professor in Arts & Sciences, is a leading authority on early human evolution and among the first to offer compelling evidence for interbreeding and gene transfer between Neandertals and modern human ancestors.

His co-authors on this study are Xiu-Jie Wu, Wu Liu and Song Xing of the Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, and Isabelle Crevecoeur of PACEA, Université de Bordeaux.

“We were completely surprised,” Trinkaus said. “We fully expected the scan to reveal a temporal labyrinth that looked much like a modern human one, but what we saw was clearly typical of a Neandertal. This discovery places into question whether this arrangement of the semicircular canals is truly unique to the Neandertals.”

Often well-preserved in mammal skull fossils, the semicircular canals are remnants of a fluid-filled sensing system that helps humans maintain balance when they change their spatial orientations, such as when running, bending over or turning the head from side-to-side.

Since the mid-1990s, when early CT-scan research confirmed its existence, the presence of a particular arrangement of the semicircular canals in the temporal labyrinth has been considered enough to securely identify fossilized skull fragments as being from a Neandertal. This pattern is present in almost all of the known Neandertal labyrinths. It has been widely used as a marker to set them apart from both earlier and modern humans.

The skull at the center of this study, known as Xujiayao 15, was found along with an assortment of other human teeth and bone fragments, all of which seemed to have characteristics typical of an early non-Neandertal form of late archaic humans.

Trinkaus, who has studied Neandertal and early human fossils from around the globe, said this discovery only adds to the rich confusion of theories that attempt to explain human origins, migrations patterns and possible interbreedings.

While it’s tempting to use the finding of a Neandertal-shaped labyrinth in an otherwise distinctly “non-Neandertal” sample as evidence of population contact (gene flow) between central and western Eurasian Neandertals and eastern archaic humans in China, Trinkaus and colleagues argue that broader implications of the Xujiayao discovery remain unclear.

“The study of human evolution has always been messy, and these findings just make it all the messier,” Trinkaus said. “It shows that human populations in the real world don’t act in nice simple patterns.

“Eastern Asia and Western Europe are a long way apart, and these migration patterns took thousands of years to play out,” he said. “This study shows that you can’t rely on one anatomical feature or one piece of DNA as the basis for sweeping assumptions about the migrations of hominid species from one place to another.”

Journal Reference:

  1. Xiu-Jie Wu, Isabelle Crevecoeur, Wu Liu, Song Xing, and Erik Trinkaus. Temporal labyrinths of eastern Eurasian Pleistocene humans. PNAS, July 7, 2014 DOI:10.1073/pnas.1410735111

Insect diet helped early humans build bigger brains: Quest for elusive bugs spurred primate tool use, problem-solving skills (Science Daily)

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Date: July 1, 2014

Source: Washington University in St. Louis

Summary: Figuring out how to survive on a lean-season diet of hard-to-reach ants, slugs and other bugs may have spurred the development of bigger brains and higher-level cognitive functions in the ancestors of humans and other primates, suggests new research.

An adult female tufted capuchin monkey of the Sapajus lineage using a stone tool and a sandstone anvil to crack a palm nut as her infant hangs on. Credit: E. Visalberghi

Figuring out how to survive on a lean-season diet of hard-to-reach ants, slugs and other bugs may have spurred the development of bigger brains and higher-level cognitive functions in the ancestors of humans and other primates, suggests research from Washington University in St. Louis.

“Challenges associated with finding food have long been recognized as important in shaping evolution of the brain and cognition in primates, including humans,” said Amanda D. Melin, PhD, assistant professor of anthropology in Arts & Sciences and lead author of the study.

“Our work suggests that digging for insects when food was scarce may have contributed to hominid cognitive evolution and set the stage for advanced tool use.”

Based on a five-year study of capuchin monkeys in Costa Rica, the research provides support for an evolutionary theory that links the development of sensorimotor (SMI) skills, such as increased manual dexterity, tool use, and innovative problem solving, to the creative challenges of foraging for insects and other foods that are buried, embedded or otherwise hard to procure.

Published in the June 2014 Journal of Human Evolution, the study is the first to provide detailed evidence from the field on how seasonal changes in food supplies influence the foraging patterns of wild capuchin monkeys.

The study is co-authored by biologist Hilary C. Young and anthropologists Krisztina N. Mosdossy and Linda M. Fedigan, all from the University of Calgary, Canada.

It notes that many human populations also eat embedded insects on a seasonal basis and suggests that this practice played a key role in human evolution.

“We find that capuchin monkeys eat embedded insects year-round but intensify their feeding seasonally, during the time that their preferred food — ripe fruit — is less abundant,” Melin said. “These results suggest embedded insects are an important fallback food.”

Previous research has shown that fallback foods help shape the evolution of primate body forms, including the development of strong jaws, thick teeth and specialized digestive systems in primates whose fallback diets rely mainly on vegetation.

This study suggests that fallback foods can also play an important role in shaping brain evolution among primates that fall back on insect-based diets, and that this influence is most pronounced among primates that evolve in habitats with wide seasonal variations, such as the wet-dry cycles found in some South American forests.

“Capuchin monkeys are excellent models for examining evolution of brain size and intelligence for their small body size, they have impressively large brains,” Melin said. “Accessing hidden and well-protected insects living in tree branches and under bark is a cognitively demanding task, but provides a high-quality reward: fat and protein, which is needed to fuel big brains.”

But when it comes to using tools, not all capuchin monkey strains and lineages are created equal, and Melin’s theories may explain why.

Perhaps the most notable difference between the robust (tufted, genus Sapajus) and gracile (untufted, genus Cebus) capuchin lineages is their variation in tool use. While Cebus monkeys are known for clever food-foraging tricks, such as banging snails or fruits against branches, they can’t hold a stick to their Sapajus cousins when it comes to theinnovative use and modification of sophisticated tools.

One explanation, Melin said, is that Cebus capuchins have historically and consistently occupied tropical rainforests, whereas the Sapajus lineage spread from their origins in the Atlantic rainforest into drier, more temperate and seasonal habitat types.

“Primates who extract foods in the most seasonal environments are expected to experience the strongest selection in the ‘sensorimotor intelligence’ domain, which includes cognition related to object handling,” Melin said. “This may explain the occurrence of tool use in some capuchin lineages, but not in others.”

Genetic analysis of mitochondial chromosomes suggests that the Sapajus-Cebus diversification occurred millions of years ago in the late Miocene epoch.

“We predict that the last common ancestor of Cebus and Sapajus had a level of SMI more closely resembling extant Cebus monkeys, and that further expansion of SMI evolved in the robust lineage to facilitate increased access to varied embedded fallback foods,necessitated by more intense periods of fruit shortage,” she said.

One of the more compelling modern examples of this behavior, said Melin, is the seasonal consumption of termites by chimpanzees, whose use of tools to extract this protein-rich food source is an important survival technique in harsh environments.

What does this all mean for hominids?

While it’s hard to decipher the extent of seasonal dietary variations from the fossil record, stable isotope analyses indicate seasonal variation in diet for at least one South African hominin, Paranthropus robustus. Other isotopic research suggests that early human diets may have included a range of extractable foods, such as termites, plant roots and tubers.

Modern humans frequently consume insects, which are seasonally important when other animal foods are limited.

This study suggests that the ingenuity required to survive on a diet of elusive insects has been a key factor in the development of uniquely human skills: It may well have been bugs that helped build our brains.

Journal Reference:

  1. Amanda D. Melin, Hilary C. Young, Krisztina N. Mosdossy, Linda M. Fedigan.Seasonality, extractive foraging and the evolution of primate sensorimotor intelligence. Journal of Human Evolution, 2014; 71: 77 DOI:10.1016/j.jhevol.2014.02.009

Domestication of Dogs May Explain Mammoth Kill Sites and the Success of Early Modern Humans (The Pennsylvania State University)

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Pat Shipman and Barbara K. Kennedy

May 30, 2014

a dog's skullA fragment of a large bone, probably from a mammoth, Pat Shipman reports, was placed in this dog’s mouth shortly after death. This finding suggests the animal was according special mortuary treatment, perhaps acknowledging its role in mammoth hunting. The fossil comes from the site of Predmosti, in the Czech republic, and is about 27,000 years B.P. old. This object is one of three canid skulls from Predmosti that were identified as dogs based on analysis of their morphology. Photo credit: Anthropos Museum, Brno, the Czech Republic, courtesy of Mietje Germonpre.

29 May 2014 — A new analysis of European archaeological sites containing large numbers of dead mammoths and dwellings built with mammoth bones has led Penn State Professor Emerita Pat Shipman to formulate a new interpretation of how these sites were formed. She suggests that their abrupt appearance may have been due to early modern humans working with the earliest domestic dogs to kill the now-extinct mammoth — a now-extinct animal distantly related to the modern-day elephant. Shipman’s analysis also provides a way to test the predictions of her new hypothesis. Advance publication of her article “How do you kill 86 mammoths?” is available online throughQuaternary International.

Spectacular archaeological sites yielding stone tools and extraordinary numbers of dead mammoths — some containing the remains of hundreds of individuals — suddenly became common in central and eastern Eurasia between about 45,000 and 15,000 years ago, although mammoths previously had been hunted by humans and their extinct relatives and ancestors for at least a million years. Some of these mysterious sites have huts built of mammoth bones in complex, geometric patterns as well as piles of butchered mammoth bones.

“One of the greatest puzzles about these sites is how such large numbers of mammoths could have been killed with the weapons available during that time,” Shipman said. Many earlier studies of the age distribution of the mammoths at these sites found similarities with modern elephants killed by hunting or natural disasters, but Shipman’s new analysis of the earlier studies found that they lacked the statistical evaluations necessary for concluding with any certainty how these animals were killed.

Surprisingly, Shipman said, she found that “few of the mortality patterns from these mammoth deaths matched either those from natural deaths among modern elephants killed by droughts or by culling operations with modern weapons that kill entire family herds of modern elephants at once.” This discovery suggested to Shipman that a successful new technique for killing such large animals had been developed and its repeated use over time could explain the mysterious, massive collections of mammoth bones in Europe.

hand-drawn mapThese maps show the locations of collections of mammoth bones at the archaeological sites that Pat Shipman analyzed in her paper that will be published in the journal Quaternary International. Credit: Jeffrey Mathison. 

The key to Shipman’s new hypothesis is recent work by a team led by Mietje Germonpré of the Royal Belgian Institute of Natural Sciences, which has uncovered evidence that some of the large carnivores at these sites were early domesticated dogs, not wolves as generally had been assumed. Then, with this evidence as a clue, Shipman used information about how humans hunt with dogs to formulate a series of testable predictions about these mammoth sites.

“Dogs help hunters find prey faster and more often, and dogs also can surround a large animal and hold it in place by growling and charging while hunters move in. Both of these effects would increase hunting success,” Shipman said. “Furthermore, large dogs like those identified by Germonpré either can help carry the prey home or, by guarding the carcass from other carnivores, can make it possible for the hunters to camp at the kill sites.” Shipman said that these predictions already have been confirmed by other analyses. In addition, she said, “if hunters working with dogs catch more prey, have a higher intake of protein and fat, and have a lower expenditure of energy, their reproductive rate is likely to rise.”

Another unusual feature of these large mammoth kill sites is the presence of extraordinary numbers of other predators, particularly wolves and foxes. “Both dogs and wolves are very alert to the presence of other related carnivores — the canids — and they defend their territories and food fiercely,” Shipman explained. “If humans were working and living with domesticated dogs or even semi-domesticated wolves at these archaeological sites, we would expect to find the new focus on killing the wild wolves that we see there.”

bonesThe photo shows part of the very-high-density concentration of mammoth bones at the Krakow-Spadzista Street archaeological site. Credit line Piotr Wojtal.

Two other types of studies have yielded data that support Shipman’s hypothesis. Hervé Bocherens and Dorothée Drucker of the University of Tubingen in Germany, carried out an isotopic analysis of the ones of wolves and purported dogs from the Czech site of Predmostí. They found that the individuals identified as dogs had different diets from those identified as wolves, possibly indicating feeding by humans. Also, analysis of mitochondrial DNA by Olaf Thalmann of the University of Turku in Finland, and others, showed that the individuals identified as dogs have a distinctive genetic signature that is not known from any other canid. “Since mitochondrial DNA is carried only by females, this finding may indicate that these odd canids did not give rise to modern domesticated dogs and were simply a peculiar, extinct group of wolves,” Shipman said. “Alternatively, it may indicate that early humans did domesticate wolves into dogs or a doglike group, but the female canids interbred with wild wolf males and so the distinctive female mitochondrial DNA lineage was lost.”

As more information is gathered on fossil canids dated to between 45,000 and 15,000 years ago, Shipman’s hunting-dog hypothesis will be supported “if more of these distinctive doglike canids are found at large, long-term sites with unusually high numbers of dead mammoths and wolves; if the canids are consistently large, strong individuals; and if their diets differ from those of wolves,” Shipman said. “Dogs may indeed be man’s best friend.”

Modern humans were not any smarter than Neanderthals, say scientists (The Christian Science Monitor)

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Neanderthals that lived in Eurasia for more than 300,000 years were skillful hunters making use of the landscape to kill animals, say researchers.

By , Staff writer / April 30, 2014

This Jan. 8, 2003 file photo shows a reconstructed Neanderthal skeleton, right, and a modern human version of a skeleton, left, on display at the Museum of Natural History in New York. AP Photo/Frank Franklin II

Some scientists have speculated that they were out-competed by brainier H. sapiens, but researchers now say that Neanderthals, who lived in Eurasia for more than 300,000 years, were not that dumb after all.

In a paper titled “Neandertal Demise: An Archaeological Analysis of the Modern Human Superiority Complex” published in PLOS One, researchers challenge the notion that modern humans were superior to Neanderthals “in a wide range of domains, including weaponry and subsistence strategies, which would have led to the demise of Neandertals.”

After examining the remains from various archaeological sites associated with Neanderthals, CU-Boulder researcher Paola Villa and co-author of the paper said, “The evidence for cognitive inferiority is simply not there. What we are saying is that the conventional view of Neanderthals is not true.”

Artifacts and remains of animal bones reveal that Neanderthals used the landscape to hunt animals. An archaeological site excavated in France shows that they used sinkhole as a trap to hunt bison. And other evidence shows the use of deep ravines to hunt animals.

“Neandertals were by all means accomplished large game hunters, who survived in a wide range of environments subsisting by hunting a wide range of animals in a variety of topographical settings,” note the researchers in their paper.

Microfossils found in their teeth show that Neanderthals had a diverse diet that included aquatic foods, small and fast game such as birds and rabbits, date palms, and grass seeds.

Recent information available on “Neandertal use of ochre and manganese as well as on Neandertal production of pitch, the presence of transported and ochre-smeared shells, of ornaments such as eagle claws and perhaps bird feathers,” goes to show that they had cultural rituals.

So far, Neanderthals have been subjected to unfair comparison because “[r]esearchers were comparing Neanderthals not to their contemporaries on other continents but to their successors,” Dr. Villa said. “It would be like comparing the performance of Model T Fords, widely used in America and Europe in the early part of the last century, to the performance of a modern-day Ferrari and conclude that Henry Ford was cognitively inferior to Enzo Ferrari.”

When it comes to what caused the demise of Neanderthals, researchers say that there is no evidence that Neanderthal extinction was due to behavioral or technological inferiority. Current genetic studies suggest that the Neanderthal demise was a complex process including many factors, such as interbreeding, possible male hybrid sterility, and assimilation by the increasing numbers of modern immigrants, Villa wrote in an email.

Talking Neanderthals challenge the origins of speech (Science Daily)

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Date:

March 2, 2014

Source: University of New England

Summary: We humans like to think of ourselves as unique for many reasons, not least of which being our ability to communicate with words. But ground-breaking research shows that our ‘misunderstood cousins,’ the Neanderthals, may well have spoken in languages not dissimilar to the ones we use today.

A model of an adult Neanderthal male head and shoulders on display in the Hall of Human Origins in the Smithsonian Museum of Natural History in Washington, D.C. Reconstruction based on the Shanidar 1 fossil (c. 80-60 kya). Credit: By reconstruction: John Gurche; photograph: Tim Evanson [CC-BY-SA-2.0], via Wikimedia Commons

We humans like to think of ourselves as unique for many reasons, not least of which being our ability to communicate with words. But ground-breaking research by an expert from the University of New England shows that our ‘misunderstood cousins,’ the Neanderthals, may well have spoken in languages not dissimilar to the ones we use today.

Pinpointing the origin and evolution of speech and human language is one of the longest running and most hotly debated topics in the scientific world. It has long been believed that other beings, including the Neanderthals with whom our ancestors shared Earth for thousands of years, simply lacked the necessary cognitive capacity and vocal hardware for speech.

Associate Professor Stephen Wroe, a zoologist and palaeontologist from UNE, along with an international team of scientists and the use of 3D x-ray imaging technology, made the revolutionary discovery challenging this notion based on a 60,000 year-old Neanderthal hyoid bone discovered in Israel in 1989.

“To many, the Neanderthal hyoid discovered was surprising because its shape was very different to that of our closest living relatives, the chimpanzee and the bonobo. However, it was virtually indistinguishable from that of our own species. This led to some people arguing that this Neanderthal could speak,” A/Professor Wroe said.

“The obvious counterargument to this assertion was that the fact that hyoids of Neanderthals were the same shape as modern humans doesn’t necessarily mean that they were used in the same way. With the technology of the time, it was hard to verify the argument one way or the other.”

However advances in 3D imaging and computer modelling allowed A/Professor Wroe’s team to revisit the question.

“By analysing the mechanical behaviour of the fossilised bone with micro x-ray imaging, we were able to build models of the hyoid that included the intricate internal structure of the bone. We then compared them to models of modern humans. Our comparisons showed that in terms of mechanical behaviour, the Neanderthal hyoid was basically indistinguishable from our own, strongly suggesting that this key part of the vocal tract was used in the same way.

“From this research, we can conclude that it’s likely that the origins of speech and language are far, far older than once thought.”

Journal Reference:

  1. Ruggero D’Anastasio, Stephen Wroe, Claudio Tuniz, Lucia Mancini, Deneb T. Cesana, Diego Dreossi, Mayoorendra Ravichandiran, Marie Attard, William C. H. Parr, Anne Agur, Luigi Capasso. Micro-Biomechanics of the Kebara 2 Hyoid and Its Implications for Speech in Neanderthals. PLoS ONE, 2013; 8 (12): e82261 DOI: 10.1371/journal.pone.0082261

Theory on origin of animals challenged: Some animals need extremely little oxygen (Science Daily)

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Date: February 17, 2014

Source: University of Southern Denmark

Summary: One of science’s strongest dogmas is that complex life on Earth could only evolve when oxygen levels in the atmosphere rose to close to modern levels. But now studies of a small sea sponge fished out of a Danish fjord shows that complex life does not need high levels of oxygen in order to live and grow.

Sea sponge Halichondria panicea was used in the experiment at the University of Southern Denmark. Credit: Daniel Mills/SDU

One of science’s strongest dogmas is that complex life on Earth could only evolve when oxygen levels in the atmosphere rose to close to modern levels. But now studies of a small sea sponge fished out of a Danish fjord shows that complex life does not need high levels of oxygen in order to live and grow.

The origin of complex life is one of science’s greatest mysteries. How could the first small primitive cells evolve into the diversity of advanced life forms that exists on Earth today? The explanation in all textbooks is: Oxygen. Complex life evolved because the atmospheric levels of oxygen began to rise app. 630 — 635 million years ago.

However new studies of a common sea sponge from Kerteminde Fjord in Denmark shows that this explanation needs to be reconsidered. The sponge studies show that animals can live and grow even with very limited oxygen supplies.

In fact animals can live and grow when the atmosphere contains only 0.5 per cent of the oxygen levels in today’s atmosphere.

“Our studies suggest that the origin of animals was not prevented by low oxygen levels,” says Daniel Mills, PhD at the Nordic Center for Earth Evolution at the University of Southern Denmark.

Together with Lewis M. Ward from the California Institute of Technology he is the lead author of a research paper about the work in the journal PNAS.

A little over half a billion years ago, the first forms of complex life — animals — evolved on Earth. Billions of years before that life had only consisted of simple single-celled life forms. The emergence of animals coincided with a significant rise in atmospheric oxygen, and therefore it seemed obvious to link the two events and conclude that the increased oxygen levels had led to the evolution of animals.

“But nobody has ever tested how much oxygen animals need — at least not to my knowledge. Therefore we decided to find out,” says Daniel Mills.

The living animals that most closely resemble the first animals on Earth are sea sponges. The species Halichondria panicea lives only a few meters from the University of Southern Denmark’s Marine Biological Research Centre in Kerteminde, and it was here that Daniel Mills fished out individuals for his research.

“When we placed the sponges in our lab, they continued to breathe and grow even when the oxygen levels reached 0.5 per cent of present day atmospheric levels,” says Daniel Mills.

This is lower than the oxygen levels we thought were necessary for animal life.

The big question now is: If low oxygen levels did not prevent animals from evolving — then what did? Why did life consist of only primitive single-celled bacteria and amoebae for billions of years before everything suddenly exploded and complex life arose?

“There must have been other ecological and evolutionary mechanisms at play. Maybe life remained microbial for so long because it took a while to develop the biological machinery required to construct an animal. Perhaps the ancient Earth lacked animals because complex, many-celled bodies are simply hard to evolve,” says Daniel Mills.

His colleagues from the Nordic Center for Earth Evolution have previously shown that oxygen levels have actually risen dramatically at least one time before complex life evolved. Although plenty of oxygen thus became available it did not lead to the development of complex life.

Journal Reference:

  1. Daniel B. Mills, Lewis M. Ward, CarriAyne Jones, Brittany Sweeten, Michael Forth, Alexander H. Treusch and Donald E. Canfield. The oxygen requirements of the earliest animals. PNAS, February 17, 2014

Humanity’s forgotten return to Africa revealed in DNA (New Scientist)

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20:00 03 February 2014 by Catherine Brahic

Call it humanity’s unexpected U-turn. One of the biggest events in the history of our species is the exodus out of Africa some 65,000 years ago, the start ofHomo sapiens‘ long march across the world. Now a study of southern African genes shows that, unexpectedly, another migration took western Eurasian DNA back to the very southern tip of the continent 3000 years ago.

According to conventional thinking, the Khoisan tribes of southern Africa, have lived in near-isolation from the rest of humanity for thousands of years. In fact, the study shows that some of their DNA matches most closely people from modern-day southern Europe, including Spain and Italy.

Because Eurasian people also carry traces of Neanderthal DNA, the finding also shows – for the first time – that genetic material from our extinct cousin may be widespread in African populations.

The Khoisan tribes of southern Africa are hunter-gatherers and pastoralists who speak unique click languages. Their extraordinarily diverse gene pool split from everyone else’s before the African exodus.

Ancient lineages

“These are very special, isolated populations, carrying what are probably the most ancient lineages in human populations today,” says David Reich of Harvard University. “For a lot of our genetic studies we had treated them as groups that had split from all other present-day humans before they had split from each other.”

So he and his colleagues were not expecting to find signs of western Eurasian genes in 32 individuals belonging to a variety of Khoisan tribes. “I think we were shocked,” says Reich.

The unexpected snippets of DNA most resembled sequences from southern Europeans, including Sardinians, Italians and people from the Basque region (see “Back to Africa – but from where?“). Dating methods suggested they made their way into the Khoisan DNA sometime between 900 and 1800 years ago – well before known European contact with southern Africa (see map).

Archaeological and linguistic studies of the region can make sense of the discovery. They suggest that a subset of the Khoisan, known as the Khoe-Kwadi speakers, arrived in southern Africa from east Africa around 2200 years ago. Khoe-Kwadi speakers were – and remain – pastoralists who make their living from herding cows and sheep. The suggestion is that they introduced herding to a region that was otherwise dominated by hunter-gatherers.

Khoe-Kwadi tribes

Reich and his team found that the proportion of Eurasian DNA was highest in Khoe-Kwadi tribes, who have up to 14 per cent of western Eurasian ancestry. What is more, when they looked at the east African tribes from which the Khoe-Kwadi descended, they found a much stronger proportion of Eurasian DNA – up to 50 per cent.

That result confirms a 2012 study by Luca Pagani of the Wellcome Trust Sanger Institute in Hinxton, UK, which found non-African genes in people living in Ethiopia. Both the 2012 study and this week’s new results show that the Eurasian genes made their way into east African genomes around 3000 years ago. About a millennium later, the ancestors of the Khoe-Kwadi headed south, carrying a weaker signal of the Eurasian DNA into southern Africa.

The cultural implications are complex and potentially uncomfortably close to European colonial themes. “I actually am not sure there’s any population that doesn’t have west Eurasian [DNA],” says Reich.

“These populations were always thought to be pristine hunter-gatherers who had not interacted with anyone for millennia,” says Reich’s collaborator, linguist Brigitte Pakendorf of the University of Lyon in France. “Well, no. Just like the rest of the world, Africa had population movements too. There was simply no writing, no Romans or Greeks to document it.”

Twist in tale

There’s one more twist to the tale. In 2010 a research team – including Reich – published the first draft genome of a Neanderthal. Comparisons with living humans revealed traces of Neanderthal DNA in all humans with one notable exception: sub-Saharan peoples like the Yoruba and Khoisan.

That made sense. After early humans migrated out of Africa around 60,000 years ago, they bumped into Neanderthals somewhere in what is now the Middle East. Some got rather cosy with each other. As their descendants spread across the world to Europe, Asia and eventually the Americas, they spread bits of Neanderthal DNA along with their own genes. But because those descendants did not move back into Africa until historical times, most of this continent remained a Neanderthal DNA-free zone.

Or so it seemed at the time. Now it appears that the Back to Africa migration 3000 years ago carried a weak Neanderthal genetic signal deep into the homeland. Indeed one of Reich’s analyses, published last month, found Neanderthal traces in Yoruba DNA (Nature, DOI: 10.1038/nature12886).

In other words, not only is western Eurasian DNA ancestry a global phenomenon, so is having a bit of Neanderthal living on inside you.

Journal reference: PNAS, DOI: 10.1073/pnas.1313787111

Back to Africa – but from where?

Reich and his colleagues found that DNA sequences in the Khoisan people most closely resemble some found in people who today live in southern Europe. That, however, does not mean the migration back to Africa started in Italy or Spain. More likely, the migration began in what is now the Middle East.

We know that southern Europeans can trace their ancestry to the Middle East. However, in the thousands of years since they – and the ancestors of the Khoisan – left the region, it has experienced several waves of immigration. These waves have had a significant effect on the genes of people living in the Middle East today, and and means southern Europeans are much closer to the original inhabitants of the Levant than modern-day Middle Easterners.

Neanderthals Leave Their Mark on Us (New York Times)

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JAN. 29, 2014

A reconstruction of a Neanderthal skeleton, right, with a modern human skeleton in the background. Frank Franklin II/Associated Press

By Carl Zimmer

Ever since the discovery in 2010 that Neanderthals interbred with the ancestors of living humans, scientists have been trying to determine how their DNA affects people today. Now two new studies have traced the history of Neanderthal DNA, and have pinpointed a number of genes that may have medical importance today.

Among the findings, the studies have found clues to the evolution of skin and fertility, as well as susceptibility to diseases like diabetes. More broadly, they show how the legacy of Neanderthals has endured 30,000 years after their extinction.

“It’s something that everyone wanted to know,” said Laurent Excoffier, a geneticist at the University of Bern in Switzerland who was not involved in the research.

Neanderthals, who became extinct about 30,000 years ago, were among the closest relatives of modern humans. They shared a common ancestor with us that lived about 600,000 years ago.

In the 1990s, researchers began finding fragments of Neanderthal DNA in fossils. By 2010 they had reconstructed most of the Neanderthal genome. When they compared it with the genomes of five living humans, they found similarities to small portions of the DNA in the Europeans and Asians.

The researchers concluded that Neanderthals and modern humans must have interbred. Modern humans evolved in Africa and then expanded out into Asia and Europe, where Neanderthals lived. In a 2012 study, the researchers estimated that this interbreeding took place between 37,000 and 85,000 years ago.

Sir Paul A. Mellars, an archaeologist at the University of Cambridge and the University of Edinburgh, who was not involved in the research, said the archaeological evidence suggested the opportunity for modern humans to mate with Neanderthals would have been common once they expanded out of Africa. “They’d be bumping into Neanderthals at every street corner,” he joked.

The first draft of the Neanderthal genome was too rough to allow scientists to draw further conclusions. But recently, researchers sequenced a far more accurate genome from a Neanderthal toe bone.

Scientists at Harvard Medical School and the Max Planck Institute for Evolutionary Anthropology in Germany compared this high-quality Neanderthal genome to the genomes of 1,004 living people. They were able to identify specific segments of Neanderthal DNA from each person’s genome.

“It’s a personal map of Neanderthal ancestry,” said David Reich of Harvard Medical School, who led the research team. He and his colleagues published their results in the journal Nature.

Living humans do not have a lot of Neanderthal DNA, Dr. Reich and his colleagues found, but some Neanderthal genes have become very common. That’s because, with natural selection, useful genes survive as species evolve. “What this proves is that these genes were helpful for non-Africans in adapting to the environment,” Dr. Reich said.

In a separate study published in Science, Benjamin Vernot and Joshua M. Akey of the University of Washington came to a similar conclusion, using a different method.

Mr. Vernot and Dr. Akey looked for unusual mutations in the genomes of 379 Europeans and 286 Asians. The segments of DNA that contained these mutations turned out to be from Neanderthals.

Both studies suggest that Neanderthal genes involved in skin and hair were favored by natural selection in humans. Today, they are very common in living non-Africans.

The fact that two independent studies pinpointed these genes lends support to their importance, said Sriram Sankararaman of Harvard Medical School, a co-author on the Nature paper. “The two methods seem to be converging on the same results.”

It is possible, Dr. Akey speculated, that the genes developed to help Neanderthal skin adapt to the cold climate of Europe and Asia.

But Dr. Akey pointed out that skin performs other important jobs, like shielding us from pathogens. “We don’t understand enough about the biology of those particular genes yet,” he said. “It makes it hard to pinpoint a reason why they’re beneficial.”

Both teams of scientists also found long stretches of the living human genomes where Neanderthal DNA was glaringly absent. This pattern could be produced if modern humans with certain Neanderthal genes could not have as many children on average as people without them. For example, living humans have very few genes from Neanderthals involved in making sperm. That suggests that male human-Neanderthal hybrids might have had lower fertility or were even sterile.

Overall, said Dr. Reich, “most of the Neanderthal genetic material was more bad than good.”

Some of the Neanderthal genes that have endured until today may be influencing people’s health. Dr. Reich and his colleagues identified nine Neanderthal genes in living humans that are known to raise or reduce the risk of various diseases, including diabetes and lupus.

To better understand the legacy of Neanderthals, Dr. Reich and his colleagues are collaborating with the UK Biobank, which collects genetic information from hundreds of thousands of volunteers. The scientists will search for Neanderthal genetic markers, and investigate whether Neanderthal genes cause any noticeable differences in anything from weight to blood pressure to scores on memory tests.

“This experiment of nature has been done,” said Dr. Reich, “and we can study it.”

Correction: January 29, 2014
An earlier version of this article misstated the living groups in which Neanderthal genes involved in skin and hair are very common. They are very common in non-Africans, not non-Asians.

Genomes of Modern Dogs and Wolves Provide New Insights On Domestication (Science Daily)

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Jan. 16, 2014 — Dogs and wolves evolved from a common ancestor between 9,000 and 34,000 years ago, before humans transitioned to agricultural societies, according to an analysis of modern dog and wolf genomes from areas of the world thought to be centers of dog domestication.

This chart depicts wolf and dog lineages as they diverge over time. (Credit: Freedma, et al / PLoS Genetics)

The study, published in PLoS Geneticson January 16, 2014, also shows that dogs are more closely related to each other than wolves, regardless of geographic origin. This suggests that part of the genetic overlap observed between some modern dogs and wolves is the result of interbreeding after dog domestication, not a direct line of descent from one group of wolves.

This reflects a more complicated history than the popular story that early farmers adopted a few docile, friendly wolves that later became our beloved, modern-day companions. Instead, the earliest dogs may have first lived among hunter-gatherer societies and adapted to agricultural life later.

“Dog domestication is more complex than we originally thought,” said John Novembre, associate professor in the Department of Human Genetics at the University of Chicago and a senior author on the study. “In this analysis we didn’t see clear evidence in favor of a multi-regional model, or a single origin from one of the living wolves that we sampled. It makes the field of dog domestication very intriguing going forward.”

The team generated the highest quality genome sequences to date from three gray wolves: one each from China, Croatia and Israel, representing three regions where dogs are believed to have originated. They also produced genomes for two dog breeds: a basenji, a breed which originates in central Africa, and a dingo from Australia, both areas that have been historically isolated from modern wolf populations. In addition to the wolves and dogs, they sequenced the genome of a golden jackal to serve as an “outgroup” representing earlier divergence.

Their analysis of the basenji and dingo genomes, plus a previously published boxer genome from Europe, showed that the dog breeds were most closely related to each other. Likewise, the three wolves from each geographic area were more closely related to each other than any of the dogs.

Novembre said this tells a different story than he and his colleagues anticipated. Instead of all three dogs being closely related to one of the wolf lineages, or each dog being related to its closest geographic counterpart (i.e. the basenji and Israeli wolf, or the dingo and Chinese wolf), they seem to have descended from an older, wolf-like ancestor common to both species.

“One possibility is there may have been other wolf lineages that these dogs diverged from that then went extinct,” he said. “So now when you ask which wolves are dogs most closely related to, it’s none of these three because these are wolves that diverged in the recent past. It’s something more ancient that isn’t well represented by today’s wolves.”

Accounting for gene flow between dogs and wolves after domestication was a crucial step in the analyses. According to Adam Freedman, a postdoctoral fellow at the University of California, Los Angeles (UCLA) and the lead author on the study, gene flow across canid species appears more pervasive than previously thought.

“If you don’t explicitly consider such exchanges, these admixture events get confounded with shared ancestry,” he said. “We also found evidence for genetic exchange between wolves and jackals. The picture emerging from our analyses is that these exchanges may play an important role in shaping the diversification of canid species.”

Domestication apparently occurred with significant bottlenecks in the historical population sizes of both early dogs and wolves. Freedman and his colleagues were able to infer historical sizes of dog and wolf populations by analyzing genome-wide patterns of variation, and show that dogs suffered a 16-fold reduction in population size as they diverged from wolves. Wolves also experienced a sharp drop in population size soon after their divergence from dogs, implying that diversity among both animals’ common ancestors was larger than represented by modern wolves.

The researchers also found differences across dog breeds and wolves in the number of amylase (AMY2B) genes that help digest starch. Recent studies have suggested that this gene was critical to domestication, allowing early dogs living near humans to adapt to an agricultural diet. But the research team surveyed genetic data from 12 additional dog breeds and saw that while most dog breeds had high numbers of amylase genes, those not associated with agrarian societies, like the Siberian husky and dingo, did not. They also saw evidence of this gene family in wolves, meaning that it didn’t develop exclusively in dogs after the two species diverged, and may have expanded more recently after domestication.

Novembre said that overall, the study paints a complex picture of early domestication.

“We’re trying to get every thread of evidence we can to reconstruct the past,” he said. “We use genetics to reconstruct the history of population sizes, relationships among populations and the gene flow that occurred. So now we have a much more detailed picture than existed before, and it’s a somewhat surprising picture.”

Journal Reference:

  1. Adam H. Freedman, Ilan Gronau, Rena M. Schweizer, Diego Ortega-Del Vecchyo, Eunjung Han, Pedro M. Silva, Marco Galaverni, Zhenxin Fan, Peter Marx, Belen Lorente-Galdos, Holly Beale, Oscar Ramirez, Farhad Hormozdiari, Can Alkan, Carles Vilà, Kevin Squire, Eli Geffen, Josip Kusak, Adam R. Boyko, Heidi G. Parker, Clarence Lee, Vasisht Tadigotla, Adam Siepel, Carlos D. Bustamante, Timothy T. Harkins, Stanley F. Nelson, Elaine A. Ostrander, Tomas Marques-Bonet, Robert K. Wayne, John Novembre. Genome Sequencing Highlights the Dynamic Early History of Dogs. PLoS Genetics, 2014; 10 (1): e1004016 DOI:10.1371/journal.pgen.1004016

Modern Caterpillars Feed at Higher Temperatures in Response to Climate Change (Science Daily)

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Dec. 19, 2013 — Caterpillars of two species of butterflies in Colorado and California have evolved to feed rapidly at higher temperatures and at a broader range of temperatures over the past 40 years, suggesting that they are evolving quickly to cope with a hotter, more variable climate.

A Colias (sulphur) butterfly. (Credit: By Greg Hume (Own work) [CC-BY-SA-3.0], via Wikimedia Commons)

The work, led by Joel Kingsolver at UNC-Chapel Hill, represents a rare instance of how recent climate change affects physiological traits, such as how the body regulates feeding behavior.

“To our knowledge, this is the first instance where we show changes in physiological traits in response to recent climate change,” says Kingsolver, Kenan Distinguished Professor of Biology in UNC’s College of Arts and Sciences, whose work appears today in the journal Functional Ecology.

Caterpillars can eat and grow only when it’s not too cold and not too hot, explains Kingsolver. But when temperatures are ideal, caterpillars eat with reckless abandon and can gain up to 20 percent of their body weight in an hour. That growth determines their ability to survive, how quickly they become adult butterflies and their ultimate reproductive success.

Jessica Higgins, a graduate student in Kingsolver’s lab who spearheaded the study, worked with fellow graduate student Heidi MacLean, Lauren Buckley, currently at the University of Washington, and Kingsolver to compare modern caterpillars to their ancestors from 40 years ago.

Their results show that the two related species of Colias (sulphur) butterflies have adapted in two ways: they not only broadened the range of their ideal feeding temperatures but also shifted their optimal feeding temperature to a higher one.

In their work, the researchers measured changes in climate at the two study sites and then examined changes in how fast caterpillar ate using current and historical data from the 1970s, collected by Kingsolver’s graduate adviser Ward Watt.

Although they found little change in the average air temperature at both study sites, they noticed that the frequency of hot temperatures — that is, temperatures that exceeded 82 degrees Fahrenheit -increased two-fold in Colorado and four-fold in California over the past 40 years.

In response to these temperature fluctuations, modern caterpillars in Colorado ate faster at higher temperatures than their 1970s counterparts. In California, the modern caterpillars ate faster at both high and low temperatures than did their ancestors, but their optimal feeding temperatures did not change.

“These two species of caterpillars adapted to the increased frequency of higher temperatures over 40 years in two different ways, but both are better suited than their ancestors to thrive in a hotter, more variable climate,” says Higgins. “Our climate is changing. The thermal physiology of these species is changing, too.”

Rapid Evolution of Novel Forms: Environmental Change Triggers Inborn Capacity for Adaptation (Science Daily)

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Dec. 12, 2013 — In the classical view of evolution, species experience spontaneous genetic mutations that produce various novel traits — some helpful, some detrimental. Nature then selects for those most beneficial, passing them along to subsequent generations. 

Surface form and cave form of Astyanax mexicanus differ in many morphological traits, the most prominent being the loss of pigmentation and the loss of eyes in the cave forms. (Credit: Courtesy of Nicolas Rohner)

It’s an elegant model. It’s also an extremely time-consuming process likely to fail organisms needing to cope with sudden, potentially life-threatening changes in their environments. Surely some other mechanism could enable more rapid adaptive response. In this week’s edition of the journal Science, a team of researchers from Harvard Medical School and Whitehead Institute report that, at least in the case of one variety of cavefish, that other agent of change is the heat shock protein known as HSP90.

“It’s a very cool story in terms of the speed of evolution,” says Nicolas Rohner, lead author of the Science paper and a postdoctoral researcher in the lab of Harvard Medical School Genetics Professor Clifford Tabin.

Rohner notes that at some point many thousands of years ago, a population of Astyanax mexicanus (a fish indigenous to northeastern Mexico) was swept from its hospitable river home into the unfriendly confines of underwater caves. Facing a dramatically different environment, the fish were forced to adapt. Living in near total darkness, the fish did away with their pigmentation, developed heightened sensory systems to detect changes in water pressure and the presence of prey and, perhaps most strikingly, they lost their eyes. Although seemingly counterintuitive, the loss of eyes is thought to be an “adaptive” or beneficial trait, as the maintenance of a complex but now useless organ would come at a high metabolic cost. Thus, the fish could reallocate their finite physiological resources to biological functions more helpful in the cave setting.

Eye loss in these fish is considered to be a demonstration of an evolutionary concept known as “standing genetic variation,” which argues that pools of genetic mutations — some potentially helpful — exist in a given population but are normally kept silent. The manifestations of these mutations, that is, their impact on observable phenotypes, don’t emerge until the population encounters stressful conditions. But what exactly keeps those mutations at bay?

Enter Whitehead Member Susan Lindquist, whose research has shown that HSP90 silences such genetic variation in a variety of organisms, from fruit flies, to yeast, to plants. Lindquist’s work found that the normally robust cellular reservoir of HSP90 becomes depleted during periods of physiological stress. The loss of HSP90 activity allowed phenotypic changes to emerge quite rapidly. Although some emergent traits found in her lab were not adaptive, some clearly were.

“The delicate balance of protein folding — especially that controlled by HSP90 — holds the key,” says Lindquist, who is also a professor of biology at MIT and an investigator of the Howard Hughes Medical Institute. “Moderate changes in the environment create stresses on protein folding, causing minor changes in the genome to have much larger effects. Because HSP90 governs the folding of the key regulators of growth and development it produces a fulcrum point for evolutionary change.”

Having seen Tabin’s work on the genetics of eye loss in cavefish, she proposed a research collaboration to determine whether HSP90 had been an evolutionary role-player in this vertebrate. The Tabin and Lindquist labs devised a complex set of experiments with cavefish and surface fish of the same species. Surface fish raised in the presence of a drug that blocks HSP90 activity (thereby mimicking a stressful environment) displayed significant variation in eye size — clearly implicating HSP90’s effects on this trait. Conversely, cavefish raised in the same conditions showed no increase in variation in the size of their eye orbits (although the cave fish have no eyes, their skulls retain the orbital cavity where their eyes once were). Intriguingly, however, these fish emerged with small orbits, showing that the genetics governing eye size remains responsive to HSP90.

Although impressive, these findings were chemically induced, leaving open the question of whether such HSP90-related effects would have been seen in nature. To answer this, researchers examined a host of conditions — ranging from pH to oxygen content to temperature — found in the surface and cave waters that are home to these fish. They discovered a considerable difference in conductivity, as measured by salinity, between cave and surface. Because low conductivity, a condition found in the caves, can trigger a heat shock response, they raised surface fish in water whose conductivity equaled that of native caves.

The results were essentially the same: fish raised in conditions of low conductivity showed significant variation in eye size. The scientists had shown that an environmental stressor could have the same effects as the chemical inhibition of HSP90.

“This is the first time that we can see in a natural setting where the stress came from and observe the variation that results,” says Tabin.

Adds Rohner: “This is the first study showing that this HSP90-mediated mechanism can be applied to vertebrates for real morphological adaptive traits.”

For Dan Jarosz, a former postdoctoral researcher in Lindquist’s lab, the study is an important validation of Lindquist’s work on evolution. Jarosz, now Assistant Professor of Chemical and Systems Biology and of Developmental Biology at Stanford University, had been involved in much of Lindquist’s work on HSP90 as a driver of evolution in yeast. He believes this latest work should help quiet those who are skeptical of the impact of this mechanism throughout the plant and animal kingdoms.

“We now have enough evidence to say that large, rapid environmental change can reveal new variation and change the outcomes of real evolution in nature,” he says.

This work is supported by the National Institutes of Health and the Damon Runyon Cancer Research Foundation.

Journal Reference:

  1. N. Rohner, D. F. Jarosz, J. E. Kowalko, M. Yoshizawa, W. R. Jeffery, R. L. Borowsky, S. Lindquist, C. J. Tabin. Cryptic Variation in Morphological Evolution: HSP90 as a Capacitor for Loss of Eyes in Cavefish. Science, 2013; 342 (6164): 1372 DOI: 10.1126/science.1240276

Domestication of Dogs May Have Elaborated On a Pre-Existing Capacity of Wolves to Learn from Humans (Science Daily)

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Dec. 3, 2013 — Wolves can learn from observing humans and pack members where food is hidden and recognize when humans only pretend to hide food, reports a study for the first time in the open-access journal Frontiers in Psychology. These findings imply that when our ancestors started to domesticate dogs, they could have built on a pre-existing ability of wolves to learn from others, not necessarily pack members.

The researchers conclude that the ability to learn from other species, including humans, is not unique to dogs but was already present in their wolf ancestors. Prehistoric humans and the ancestors of dogs could build on this ability to better coordinate their actions. (Credit: Wolf Science Center)

A paper published recently in the journalScience suggested that humans domesticated dogs about 18 thousand years ago, possibly from a European population of grey wolves that is now extinct. But it remains unknown how much the ability of dogs to communicate with people derives from pre-existing social skills of their wolf ancestors, rather than from novel traits that arose during domestication.

In a recent study, Friederike Range and Zsófia Virányi from the Messerli Research Institute at the University of Veterinary Medicine Vienna investigated if wolves and dogs can observe a familiar “demonstrator” — a human or a specially trained dog — to learn where to look for food within a meadow. The subjects were 11 North American grey wolves and 14 mutts, all between 5 and 7 months old, born in captivity, bottle-fed, and hand-raised in packs at the Wolf Science Center of Game Park Ernstbrunn, Austria.

The wolves and dogs were two to four times more likely to find the snack after watching a human or dog demonstrator hide it, and this implies that they had learnt from the demonstration instead of only relying on their sense of smell. Moreover, they rarely looked for the food when the human demonstrator had only pretended to hide it, and this proves that they had watched very carefully.

The wolves were less likely to follow dog demonstrators to hidden food. This does not necessarily mean that they were not paying attention to dog demonstrators: on the contrary, the wolves may have been perceptive enough to notice that the demonstrator dogs did not find the food reward particularly tasty themselves, and so simply did not bother to look for it.

The researchers conclude that the ability to learn from other species, including humans, is not unique to dogs but was already present in their wolf ancestors. Prehistoric humans and the ancestors of dogs could build on this ability to better coordinate their actions.

Journal Reference:

  1. Friederike Range and Zsófia Virányi. Social learning from humans or conspecifics: differences and similarities between wolves and dogs. Frontiers In Science, 2013 DOI:10.3389/fpsyg.2013.00868

Homem evolui mais devagar que macaco, diz estudo (Folha de S.Paulo)

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24 de outubro de 2013

Reportagem da Folha de SP mostra que pesquisa descobriu que diferenças entre espécies está em genes ativos

A comparação da atividade genética de humanos com a de chimpanzés sugere que o Homo sapiens está evoluindo de forma mais lenta que os macacos. A descoberta foi feita por cientistas que investigam por que o homem e seu primo mais próximo são tão diferentes, apesar de terem 98% do DNA idêntico.

O segredo das diferenças físicas e comportamentais está em quais genes são de fato ativos em cada espécie. Analisando células embrionárias, a brasileira Carolina Marchetto, do Instituto Salk, de San Diego (EUA), descobriu mecanismos que freiam a taxa de transformação genética da espécie humana.

A descoberta favorece a hipótese de que o advento da cultura desacelerou a evolução biológica: uma vez que humanos se adaptam a distintos ambientes usando o conhecimento, nossa espécie não depende mais tanto de variação genética para evoluir e sobreviver a mudanças.

Já os macacos, mamíferos de cognição mais limitada, precisam que seu DNA evolua de forma rápida para sobreviver a mudanças: eles não têm como compensar a falta de características inatas necessárias usando apenas conhecimento e tecnologia.

Mas o DNA humano também não carece de evoluir? “Não sabemos o que estamos pagando por isso em termos de adaptação, mas por enquanto funciona de forma eficiente”, diz Marchetto.

O trabalho da cientista, descrito hoje na revista “Nature”, ajuda a explicar o mistério da maior diversidade do DNA símio. Um leigo pode achar que todos os chimpanzés são iguais, mas uma só colônia selvagem desses macacos na África tem mais variabilidade genética do que toda a humanidade.

O PULO DO GENE

Segundo o estudo de Marcheto, a maior variabilidade genética dos macacos tem a ver com os chamados transpósons, genes que saltam de um lugar para outro dos cromossomos. Nesse processo, os transpósons reorganizam o genoma, ativando alguns genes e desativando outros.

Esses “genes saltadores” são bastante ativos em chimpanzés e bonobos (macacos igualmente próximos da linhagem humana). Em humanos, o transpóson é suprimido por dois outros genes que são ativados em abundância e inibem o “pulo” genético.

Chimpanzés, de certa forma, precisam de transpósons. Com ferramentas rudimentares e sem linguagem para transmitir conhecimento, eles têm de oferecer maior variabilidade genética à seleção natural para que ela os torne mais bem adaptados, caso o ambiente se altere.

A pesquisa de Marchetto só foi possível porque seu o laboratório no Salk, liderado pelo biólogo Fred Gage, domina a técnica de reverter células ao estágio embrionário.

O material usado na pesquisa foi extraído da pele de macacos e pessoas, pois há uma série de limitações para o uso de embriões em experimentos científicos.

Revertido ao estágio de “células pluripotentes induzidas”, o tecido cutâneo se comporta como embrião, e é possível investigar a biologia molecular dos estágios iniciais do desenvolvimento, quando o surgimento de diversidade genética tem consequências futuras.

“Uma das coisas especiais do nosso estudo é que a reprogramação de células de chimpanzés e bonobos nos dá um modelo para começar a estudar questões evolutivas que antes não tínhamos como abordar”, diz Marchetto.

RUMO AO CÉREBRO

As diferenças de ativação de genes entre humanos e chimpanzés, explica, não se restringem a células embrionárias. A ideia de Marcheto e de seus colegas agora é transformar essas células em neurônios, por exemplo, para entender como a biologia molecular de ambos se altera durante a formação do cérebro.

(Rafael Garcia/ Folha de São Paulo)

http://www1.folha.uol.com.br/ciencia/2013/10/1361208-homem-evolui-mais-devagar-que-macaco-diz-estudo.shtml