Arquivo da tag: Neandertais

What Did Neanderthals Leave to Modern Humans? Some Surprises (New York Times)

Geneticists tell us that somewhere between 1 and 5 percent of the genome of modern Europeans and Asians consists of DNA inherited from Neanderthals, our prehistoric cousins.

At Vanderbilt University, John Anthony Capra, an evolutionary genomics professor, has been combining high-powered computation and a medical records databank to learn what a Neanderthal heritage — even a fractional one — might mean for people today.

We spoke for two hours when Dr. Capra, 35, recently passed through New York City. An edited and condensed version of the conversation follows.

Q. Let’s begin with an indiscreet question. How did contemporary people come to have Neanderthal DNA on their genomes?

A. We hypothesize that roughly 50,000 years ago, when the ancestors of modern humans migrated out of Africa and into Eurasia, they encountered Neanderthals. Matings must have occurred then. And later.

One reason we deduce this is because the descendants of those who remained in Africa — present day Africans — don’t have Neanderthal DNA.

What does that mean for people who have it? 

At my lab, we’ve been doing genetic testing on the blood samples of 28,000 patients at Vanderbilt and eight other medical centers across the country. Computers help us pinpoint where on the human genome this Neanderthal DNA is, and we run that against information from the patients’ anonymized medical records. We’re looking for associations.

What we’ve been finding is that Neanderthal DNA has a subtle influence on risk for disease. It affects our immune system and how we respond to different immune challenges. It affects our skin. You’re slightly more prone to a condition where you can get scaly lesions after extreme sun exposure. There’s an increased risk for blood clots and tobacco addiction.

To our surprise, it appears that some Neanderthal DNA can increase the risk for depression; however, there are other Neanderthal bits that decrease the risk. Roughly 1 to 2 percent of one’s risk for depression is determined by Neanderthal DNA. It all depends on where on the genome it’s located.

Was there ever an upside to having Neanderthal DNA?

It probably helped our ancestors survive in prehistoric Europe. When humans migrated into Eurasia, they encountered unfamiliar hazards and pathogens. By mating with Neanderthals, they gave their offspring needed defenses and immunities.

That trait for blood clotting helped wounds close up quickly. In the modern world, however, this trait means greater risk for stroke and pregnancy complications. What helped us then doesn’t necessarily now.

Did you say earlier that Neanderthal DNA increases susceptibility to nicotine addiction?

Yes. Neanderthal DNA can mean you’re more likely to get hooked on nicotine, even though there were no tobacco plants in archaic Europe.

We think this might be because there’s a bit of Neanderthal DNA right next to a human gene that’s a neurotransmitter implicated in a generalized risk for addiction. In this case and probably others, we think the Neanderthal bits on the genome may serve as switches that turn human genes on or off.

Aside from the Neanderthals, do we know if our ancestors mated with other hominids?

We think they did. Sometimes when we’re examining genomes, we can see the genetic afterimages of hominids who haven’t even been identified yet.

A few years ago, the Swedish geneticist Svante Paabo received an unusual fossilized bone fragment from Siberia. He extracted the DNA, sequenced it and realized it was neither human nor Neanderthal. What Paabo found was a previously unknown hominid he named Denisovan, after the cave where it had been discovered. It turned out that Denisovan DNA can be found on the genomes of modern Southeast Asians and New Guineans.

Have you long been interested in genetics?

Growing up, I was very interested in history, but I also loved computers. I ended up majoring in computer science at college and going to graduate school in it; however, during my first year in graduate school, I realized I wasn’t very motivated by the problems that computer scientists worked on.

Fortunately, around that time — the early 2000s — it was becoming clear that people with computational skills could have a big impact in biology and genetics. The human genome had just been mapped. What an accomplishment! We now had the code to what makes you, you, and me, me. I wanted to be part of that kind of work.

So I switched over to biology. And it was there that I heard about a new field where you used computation and genetics research to look back in time — evolutionary genomics.

There may be no written records from prehistory, but genomes are a living record. If we can find ways to read them, we can discover things we couldn’t know any other way.

Not long ago, the two top editors of The New England Journal of Medicine published an editorial questioning “data sharing,” a common practice where scientists recycle raw data other researchers have collected for their own studies. They labeled some of the recycling researchers, “data parasites.” How did you feel when you read that?

I was upset. The data sets we used were not originally collected to specifically study Neanderthal DNA in modern humans. Thousands of patients at Vanderbilt consented to have their blood and their medical records deposited in a “biobank” to find genetic diseases.

Three years ago, when I set up my lab at Vanderbilt, I saw the potential of the biobank for studying both genetic diseases and human evolution. I wrote special computer programs so that we could mine existing data for these purposes.

That’s not being a “parasite.” That’s moving knowledge forward. I suspect that most of the patients who contributed their information are pleased to see it used in a wider way.

What has been the response to your Neanderthal research since you published it last year in the journal Science?

Some of it’s very touching. People are interested in learning about where they came from. Some of it is a little silly. “I have a lot of hair on my legs — is that from Neanderthals?”

But I received racist inquiries, too. I got calls from all over the world from people who thought that since Africans didn’t interbreed with Neanderthals, this somehow justified their ideas of white superiority.

It was illogical. Actually, Neanderthal DNA is mostly bad for us — though that didn’t bother them.

As you do your studies, do you ever wonder about what the lives of the Neanderthals were like?

It’s hard not to. Genetics has taught us a tremendous amount about that, and there’s a lot of evidence that they were much more human than apelike.

They’ve gotten a bad rap. We tend to think of them as dumb and brutish. There’s no reason to believe that. Maybe those of us of European heritage should be thinking, “Let’s improve their standing in the popular imagination. They’re our ancestors, too.’”

Anúncios

As vantagens evolutivas de termos feito sexo com os neandertais (El País)

Novos indícios de que antigos cruzamentos entre as três espécies tiveram consequências evolutivas

Localização geográfica das 159 populações estudadas.

Localização geográfica das 159 populações estudadas. SCIENCE

Estamos tão acostumados a ser os únicos humanos sobre a Terra que quase não podemos imaginar um passado em que, saindo da África para um mundo desconhecido, o mais fácil era encontrar pelo caminho gentes de outras espécies do gênero Homo que compartilhavam conosco um passado esquecido, e com as quais, conforme sabemos agora, não descartávamos compartilhar o sonho de uma noite de verão. Sem que nossa lógica mais profunda, a genética, considerasse isso algo inconveniente.

Segundo a última pesquisa de 1.523 genomas de pessoas de todo o mundo, incluindo pela primeira vez os de 35 melanésios, os neandertais se relacionaram não uma, mas três vezes (em três épocas diferentes), com diversas populações de humanos modernos. Só ficaram de fora os africanos, pela simples razão de que os neandertais não estavam ali. Os melanésios atuais carregam o DNA de outra espécie arcaica, os misteriosos denisovanos que viviam na Sibéria há 50.000 anos, mas nem por isso se livraram da promiscuidade neandertal: seus genomas atuais têm as marcas inconfundíveis tanto de neandertais como de denisovanos.

E um prêmio de consolação: os genes da evolução do córtex, a sede da mente humana, são inteiramente nossos, dos Homo sapiens. Os demais parecem ser adaptações ao clima local. São os resultados que 17 cientistas da Universidade de Washington em Seattle, a Universidade de Ferrara, o Instituto Max Planck de Antropologia Evolutiva em Leipzig e o Instituto de Pesquisa Médica da Goroka, na Papua Nova Guiné, entre outros, apresentaram na revista Science.

Os genomas costumam ser medidos em megabases, ou milhões de bases (as letras do DNA, gatacca…). O genoma humano tem 3.235 megabases. Dessas, 51 megabases são arcaicas nos europeus, 55 nos asiáticos meridionais e 65 nos asiáticos orientais. Quase todas essas sequências arcaicas são de origem neandertal nessas populações. Em contraste, os melanésios apresentam uma média de 104 megabases arcaicas, das quais 49 são neandertais e 43 são denisovanas (as 12 restantes são ambíguas por enquanto). São só números, mas dão uma ideia do grau de precisão alcançado pela genômica humana.

Segundo a última pesquisa, os neandertais se cruzaram não uma, mas três vezes (em três épocas diferentes), com diversas populações de humanos modernos

Mas o diabo mora nos detalhes. As sequências arcaicas não estão distribuídas de maneira homogênea pelo genoma, muito pelo contrário. Há zonas onde estão muito pouco representadas, ou seja, onde há trechos de 8 megabases ou mais sem uma única letra neandertal ou denisovana. Estes trechos de puro DNA moderno, ou sapiens, são ricos em genes implicados no desenvolvimento do córtex cerebral – a sede da mente humana – e o corpo estriado (ou núcleo estriado), uma região interna do cérebro responsável pelos mecanismos de recompensa e, portanto, envolvida a fundo no planejamento de ações e na tomada de decisões.

Segundo as análise estatísticas dos autores, não é por mera casualidade que os genes envolvidos nessas altas funções mentais estão livres de sequências neandertais ou denisovanas. O fato implica, provavelmente, que a presença de DNA arcaico ali se revelou desvantajosa durante os últimos 50 milênios e, portanto, foi varrida pela seleção natural.

Entre os genes modernos se encontra o famoso gene da linguagem, FOXP2, o que volta a levantar dúvidas sobre a capacidade de linguagem dos neandertais. A sequência idêntica deste gene em neandertais e sapiens foi considerada uma prova de que os neandertais falavam, mas os genes são mais que sua sequência de código (a que se traduz em proteínas): existem ainda zonas reguladoras essenciais, as que dizem ao gene onde, quando e quanto se ativar. Outros genes puramente modernos são, quando em mutação, os responsáveis pelo autismo.

Entre os genes modernos se encontra o famoso gene da linguagem, FOXP2, o que volta a levantar dúvidas sobre a capacidade de linguagem dos neandertais

Também são interessantes as regiões genômicas contrárias, isto é, as particularmente ricas em genes neandertais ou denisovanos. Os genomas melanésios revelaram 21 regiões desse tipo que mostram evidências de terem sido favorecidas pela seleção natural. Muitas delas contêm genes implicados no metabolismo (a cozinha da célula), como o do hormônio GCG, que incrementa os níveis de glicose no sangue, ou o da proteína PLPP1, encarregada de processar as gorduras; também há cinco genes implicados na resposta imune inata, a primeira linha de defesa contra as infecções.

Tudo isso reforça os indícios anteriores de que os cruzamentos de nossos ancestrais sapiens com as espécies arcaicas que encontraram durante suas migrações fora do continente africano foram importantes para adaptar-se às condições locais: clima, dieta e infecções frequentes na região. Faz sentido, certamente.

Foram sonhos de uma noite do verão, mas voltam agora para nosso encontro, como em uma boa peça de teatro clássico.

Did a Volcanic Cataclysm 40,000 Years Ago Trigger the Final Demise of the Neanderthals? (Geological Society of America)

19 March 2015

Boulder, Colo., USA – The Campanian Ignimbrite (CI) eruption in Italy 40,000 years ago was one of the largest volcanic cataclysms in Europe and injected a significant amount of sulfur-dioxide (SO2) into the stratosphere. Scientists have long debated whether this eruption contributed to the final extinction of the Neanderthals. This new study by Benjamin A. Black and colleagues tests this hypothesis with a sophisticated climate model.

Black and colleagues write that the CI eruption approximately coincided with the final decline of Neanderthals as well as with dramatic territorial and cultural advances among anatomically modern humans. Because of this, the roles of climate, hominin competition, and volcanic sulfur cooling and acid deposition have been vigorously debated as causes of Neanderthal extinction.

They point out, however, that the decline of Neanderthals in Europe began well before the CI eruption: “Radiocarbon dating has shown that at the time of the CI eruption, anatomically modern humans had already arrived in Europe, and the range of Neanderthals had steadily diminished. Work at five sites in the Mediterranean indicates that anatomically modern humans were established in these locations by then as well.”

“While the precise implications of the CI eruption for cultures and livelihoods are best understood in the context of archaeological data sets,” write Black and colleagues, the results of their study quantitatively describe the magnitude and distribution of the volcanic cooling and acid deposition that ancient hominin communities experienced coincident with the final decline of the Neanderthals.

In their climate simulations, Black and colleagues found that the largest temperature decreases after the eruption occurred in Eastern Europe and Asia and sidestepped the areas where the final Neanderthal populations were living (Western Europe). Therefore, the authors conclude that the eruption was probably insufficient to trigger Neanderthal extinction.

However, the abrupt cold spell that followed the eruption would still have significantly impacted day-to-day life for Neanderthals and early humans in Europe. Black and colleagues point out that temperatures in Western Europe would have decreased by an average of 2 to 4 degrees Celsius during the year following the eruption. These unusual conditions, they write, may have directly influenced survival and day-to-day life for Neanderthals and anatomically modern humans alike, and emphasize the resilience of anatomically modern humans in the face of abrupt and adverse changes in the environment.

FEATURED ARTICLE
Campanian Ignimbrite volcanism, climate, and the final decline of the Neanderthals
Benjamin A. Black et al., University of California, Berkeley, California, USA. Published online ahead of print on 19 March 2015; http://dx.doi.org/10.1130/G36514.1.

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

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.

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

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 humansPNAS, July 7, 2014 DOI:10.1073/pnas.1410735111

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

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)

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 NeanderthalsPLoS ONE, 2013; 8 (12): e82261 DOI: 10.1371/journal.pone.0082261

Revolução neandertal (Folha de S.Paulo)

JC e-mail 4907, de 07 de março de 2014

Svante Pääbo, cientista que liderou o mapeamento do genoma do homem de Neandertal, conta em livro sua descoberta que abalou a antropologia

A história de como os humanos deixaram a África e povoaram o resto do mundo tem hoje seu foco em pesquisas sobre o DNA, deixando os fósseis –matéria-prima indispensável da antropologia– meio fora dos holofotes. Há quem questione se essa mudança é benéfica, mas é difícil desvincular essa revolução acadêmica do nome de um cientista: Svante Pääbo.

Em novo livro, o geneticista sueco radicado na Alemanha conta como essa mudança de perspectiva se instalou. Para tal, narra a história de seu principal objetivo científico, o sequenciamento do genoma do homem de Neandertal, a última criatura do gênero Homo a pisar na Terra antes de o Homo sapiens tomar o planeta inteiro para si.

Pääbo é o sujeito magricela que aparece em uma fotografia estampada em vários jornais em 7 de maio de 2010 na qual está olhando para um crânio de neandertal. Naquele dia, quando o cientista publicou a primeira versão do genoma do hominídeo extinto, teorias de evolução humana baseadas apenas na interpretação do formato de fósseis começaram a ter de ser alteradas para acomodar algumas revelações.

Aquela que chamou mais a atenção, sem dúvida, foi a de que H. sapiens e H. neanderthalensis legaram ao planeta os frutos de uma inusitada história de amor. Pessoas de etnias europeias ainda carregam no DNA cerca de 3% de ancestralidade neandertal.

O genoma desse hominídeo e a descoberta subsequente de uma linhagem totalmente nova do gênero Homo –os denisovanos, descritos por Pääbo com base no DNA extraído de um único osso de dedo– mostraram que a saída da África foi um processo bem mais complexo.

Achar DNA em ossos com dezenas de milhares de anos, porém, não era (e não é) coisa trivial. Pääbo, que se descreve como um sujeito paranoico por limpeza (para evitar contaminar amostras), também exigia de si repetir seus experimentos inúmeras vezes, cada vez que obtinha um bom resultado. Não poupa, por isso, criticas às revistas “Science” e “Nature” por terem publicado estudos que considera de baixo padrão.

Com o modesto título “Neanderthal Man”, o livro conta muito mais do que a história do sequenciamento de um genoma. Pääbo começou sua carreira acadêmica patinando entre disciplinas tão distintas quanto egiptologia e bioquímica. Seu ponto de virada foi a extração de DNA de uma múmia egípcia, estudo que realizou escondido de seu orientador de doutorado, usando uma amostra cedida por um museu da Alemanha Oriental. (O curador que cedeu o pedaço de múmia foi depois abordado pela Stasi, a polícia comunista.)

Uma boa parte do livro é dedicada a tecnicalidades de extração de DNA, apesar de as histórias de negociações para obtenção de fósseis serem mais interessantes.

No meio dos trabalhos de sequenciamento do neandertal, Pääbo conta sobre o racha com seu colaborador Ed Rubin, do Laboratório Nacional Lawrence Berkeley, que passou a competir diretamente por amostras de fósseis.

Além de intriga, há também um bocado de romance para o que se espera de um livro de ciência. Abertamente bissexual, Pääbo não se intimida em contar a história de um triângulo amoroso que envolveu sua mulher e outro cientista de seu instituto.

Nada disso, porém, é narrado mais passionalmente do que a epopeia científica do genoma do neandertal, que mudou a noção sobre o que significa ser humano.

(Rafael Garcia/Folha de S.Paulo)
http://www1.folha.uol.com.br/fsp/cienciasaude/155225-revolucao-neandertal.shtml

Neanderthals Leave Their Mark on Us (New York Times)

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.