Humans Played Role in Neanderthal Extinction

neanderthal-human-skulls

neanderthal-human-skulls

Ancient teeth from Italy suggest that the arrival of modern humans in Western Europe coincided with the demise of Neanderthals there, researchers said.

This finding suggests that modern humans may have caused Neanderthals to go extinct, either directly or indirectly, scientists added.

Neanderthals are the closest extinct relatives of modern humans. Recent findings suggest that Neanderthals, who once lived in Europe and Asia, were closely enough related to humans to interbreed with the ancestors of modern humans — about 1.5 to 2.1 percent of the DNA of anyone outside Africa is Neanderthal in origin. Recent findings suggest that Neanderthals disappeared from Europe between about 41,000 and 39,000 years ago.

Scientists have hotly debated whether Neanderthals were driven into extinction because of modern humans. To solve this mystery, researchers have tried pinpointing when modern humans entered Western Europe. [Image Gallery: Our Closest Human Ancestor]

Modern human or Neanderthal?

The Protoaurignacians, who first appeared in southern Europe about 42,000 years ago, could shed light on the entrance of modern humans into the region. This culture was known for its miniature blades and for simple ornaments made of shells and bones.

Scientists had long viewed the Protoaurignacians as the precursors of the Aurignacians — modern humans named after the site of Aurignac in southern France who spread across Europe between about 35,000 and 45,000 years ago. Researchers had thought the Protoaurignacians reflected the westward spread of modern humans from the Near East — the part of Asia between the Mediterranean Sea and India that includes the Middle East.

However, the classification of the Protoaurignacians as modern human or Neanderthal has long been uncertain. Fossils recovered from Protoaurignacian sites were not conclusively identified as either.

Now scientists analyzing two 41,000-year-old teeth from two Protoaurignacian sites in Italy find that the fossils belonged to modern humans.

“We finally have proof for the argument that says that modern humans were there when the Neanderthals went extinct in Europe,” study lead author Stefano Benazzi, a paleoanthropologist at the University of Bologna in Ravenna, Italy.

A fossil tooth found at an Italian site called Grotta di Fumane (shown here) came from a modern human, scientists say.

The researchers investigated a lower incisor tooth from Riparo Bombrini, an excavation site in Italy, and found it had relatively thick enamel. Prior research suggested modern human teeth had thicker enamel than those of Neanderthals, perhaps because modern humans were healthier or developed more slowly. They also compared DNA from an upper incisor tooth found in another site in Italy — Grotta di Fumane — with that of 52 present-day modern humans, 10 ancient modern humans, a chimpanzee, 10 Neanderthals, two members of a recently discovered human lineage known as the Denisovans, and one member of an unknown kind of human lineage from Spain, and found that the Protoaurignacian DNA was modern human.

“This research really could not have been done without the collaboration of researchers in many different scientific research fields — paleoanthropologists, molecular anthropologists, physical anthropologists, paleontologists and physicists working on dating the fossils,” Benazzi said.

Killing off Neanderthals

Since the Protoaurignacians first appeared in Europe about 42,000 years ago and the Neanderthals disappeared from Europe between about 41,000 and 39,000 years ago, these new findings suggest that Protoaurignacians “caused, directly or indirectly, the demise of Neanderthals,” Benazzi said.

These 3D models show an incisor tooth from two Italian sites, Riparo Bombrini (left) and Grotta di Fumane (right).
Credit: Daniele Panetta, CNR Institute of Clinical Physiology, Pisa, Italy

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It remains unclear just how modern humans might have driven Neanderthals into extinction, Benazzi cautioned. Modern humans might have competed with Neanderthals, or they might simply have assimilated Neanderthals into their populations.

Moreover, prior research suggests that Neanderthals in Europe might have been headed toward extinction before modern humans even arrived on the continent. Neanderthals apparently experienced a decline in genetic diversity about the time when modern humans began turning up in Europe.

“The only way we might have proof of how modern humans caused the decline of Neanderthals is if we ever find a modern human burying a knife into the head of a Neanderthal,” Benazzi joked.

The researchers now hope to find more Protoaurignacian human remains. “Hopefully, we can find DNA that may say something about whether these modern humans and Neanderthals interbred,” Benazzi said.

 

Source:   livescience.com

Attracted to Neanderthals

Attracted to Neanderthals:

 

Attracted to Neanderthals

Attracted to Neanderthals

Two new studies regarding our genetic relationship with Neanderthals have reached similar conclusions : Makes between 85,000 and 37,000 years after modern humans migrated groups outside Africa, who mated with Neanderthals. Neanderthals died out 30,000 years ago, are the closest relatives to humans , sharing a common ancestor 600,000 years ago.

The researchers say that the Neanderthal DNA related to the hair and skin is particularly present in the DNA of some modern humans . ” In an article published in the journal Nature , researchers at Harvard Medical School and the Max Planck Institute of Anthropology evolutionary in Germany concluded that Neanderthal DNA is particularly similar to the DNA of Europeans and Asians, while another group of researchers from the University of Washington came to similar conclusions. Both studies indicate that Neanderthals genes are now very common in non-African people alive today.

Thus, although the stooped posture and thick eyebrow Neanderthal not seem attractive to the contemporary human being , perhaps a being that was protected by a tangle of hair – hair full, with the strongest bark skin was just the best thing long ago modern humans had ever seen. And Neanderthals also had larger cranial capacity – so, you know , certainly had the wit and wisdom of human courting newcomers.

Disease picked up through interbreeding with Neanderthals

Disease in people today were picked up through interbreeding with Neanderthals:

 

Disease in people today were picked up through interbreeding with Neanderthals

Disease in people today were picked up through interbreeding with Neanderthals

Genome studies reveal that our species (Homo sapiens) mated with Neanderthals after leaving Africa.

But what was clear before this Neanderthal DNA did and if there was any impact on human health .

When Neanderthals and modern humans met and mixed , they were on the very edge of being compatible biological ”

Harvard Medical School Prof David Reich

Between 2% and 4% of the genetic fingerprint of non-Africans today came from Neanderthals.

By screening the genomes of 1,004 modern humans, Sriram Sankararaman and colleagues identified the regions that carry different versions of Neanderthal genes.

Genetic variant associated with a difficulty in quitting should be found to have a Neanderthal origin is a surprise.

There is no suggestion of our evolutionary cousins ​​were smoking in their caves.

Instead, the researchers argue , this mutation may have more than one function , so the modern effect of this marker in smoking behavior may be one of the impacts it has among many.

The researchers found that the DNA Neanderthal not evenly distributed throughout the human genome , rather than being commonly found in the regions that affect the skin and hair .

This suggests some variants of the gene provided a quick way to modern to suit the new cooler environments they encountered as they moved in Eurasia humans. When populations were found , Neanderthals had already been adapted to these conditions for several hundred thousand years.

Chubby Chasers once covered the gamut from Britain to Siberia, but became extinct about 30,000 years ago, as Homo sapiens was spreading from an African country.

Neanderthal ancestry was found in regions of the genome associated with the regulation of skin pigmentation .

I think what we’re seeing in many ways they are the dying remains of this extinct genome as slowly purged human populations ”

Joshua Akey University of Washington

“We found evidence that genes of skin Neanderthals did Europeans and East Asians more evolutionarily fit,” said Benjamin Vernot , University of Washington, co -author of a separate study in Science magazine .

The genes of keratin filaments , a fibrous protein that lends itself to the hardness of the skin, hair and nails, also enriched with Neanderthal DNA . This may have helped provide newcomers with thicker insulation against the cold, the scientists suggest .

“It is tempting to think that Neanderthals already adapted to the environment does not always lead African and genetics ( modern) humans,” said Professor David Reich of Harvard Medical School , co-author of the Nature paper .

But other gene variants influence human diseases , such as type 2 diabetes, long-term depression , lupus, biliary cirrhosis – an autoimmune liver disease – Crohn ‘s disease and . For Crohn ‘s disease , Neanderthals passed on markers that increase and decrease the risk of disease .

Asked whether our ancient relatives actually suffering from these diseases as well, or whether mutations in question only affected the risk of disease when transplanted to a modern human gene pool , Mr. Sankararaman said : “We have a fine knowledge of genetics the Neanderthals to answer this , “but added that further study of their genomes may she light on this issue.

Joshua Akey , University of Washington, one of the authors of the journal Science , added: “Mixture happened relatively recently in evolutionary terms , so you can not expect the entire Neanderthal DNA have been swept away by this point.

“I think what we’re seeing in many ways they are the dying remains of this extinct genome as slowly purged of the human population .

However, some regions of the genome were found to be devoid of Neanderthal DNA , suggesting that certain genes had such adverse effects in the offspring of matings by modern Neanderthal that indeed have been emptied and actively quickly through natural selection .

“We found that there are large regions of the genome where most modern humans have little or no Neanderthal ancestry. ”

“This reduction of Neanderthal ancestry was probably due to selection against genes that were wrong – harmful – . For us ”

Neanderthal deficient regions include genes that are specifically expressed in the testes and in the X ( female ) chromosome .

This suggests that some human hybrids – modern Neanderthals had reduced fertility and in some cases were sterile.

” We are told that when Neanderthals and modern humans met and mixed , they were on the verge of being biologically compatible” said Professor Reich.

Another region of the genome includes genes neanderthales lacked a gene called FOXP2 , which is believed to play an important role in human speech .

Joshua Akey said his team’s findings were consistent with that there have been multiple pulses cross between modern humans and Neanderthals .

 

Ancient Humans Interbred Extensively “Unknown Population”

Genetic Analysis Suggests Ancient Humans Interbred Extensively Neanderthals, Denisovans And An “Unknown Population”:

 

Ancient Humans Interbred Extensively “Unknown Population”

Ancient Humans Interbred Extensively “Unknown Population”

Genome analysis suggests there was interbreeding between modern humans, Neanderthals, Denisovans and an unknown archaic population. Updated genome sequences from two extinct relatives of modern humans suggest that these ‘archaic’ groups bred with humans and with each other more extensively than was previously known.

The ancient genomes, one from a Neanderthal and one from a member of an archaic human group called the Denisovans, were presented on 18 November at a meeting on ancient DNA at the Royal Society in London. The results suggest that interbreeding went on between the members of several ancient human-like groups in Europe and Asia more than 30,000 years ago, including an as-yet-unknown human ancestor from Asia.

All modern humans whose ancestry originates outside of Africa owe about 2% of their genome to Neanderthals. Certain populations living in Oceania, such as Papua New Guineans and Australian Aboriginals, share about 4% of their DNA with Denisovans.

Neanderthals did not interbreed with humans

The genetic traits between humans and Neanderthals are more likely from a shared ancestry rather than interbreeding, a British study has suggested:

 Neanderthals did not interbreed with humans, scientists find


Neanderthals did not interbreed with humans, scientists find

Their analysis contradicts recent studies that found inter-species mating, known as hybridisation, probably occurred. Cambridge University researchers concluded that the DNA similarities were unlikely to be the result of human-Neanderthal sex during their 15,000-year coexistence in Europe. People living outside Africa share as much as four per cent of their DNA with Neanderthals, a cave-dwelling species with muscular short arms and legs and a brain slightly larger than ours. The Cambridge researchers examined demographic patterns suggesting that humans were far from intimate with the species they displaced in Europe almost 40,000 years ago. The study into the genomes of the two species, found a common ancestor 500,000 years ago would be enough to account for the shared DNA. Their analysis, published in the journal Proceedings of the National Academy of Sciences (PNAS), contradicts recent studies that found inter-species mating, known as hybridisation, probably occurred. Dr Andrea Manica, who led the study, said: “To me the interbreeding question is not whether there was hybridisation but whether there was any hybridisation that affected the subsequent evolution of humans. I think this is very, very unlikely. “Our work shows clearly the patterns currently seen in the Neanderthal genome are not exceptional, and are in line with our expectations of what we would see without hybridisation. “So, if any hybridisation happened then it would have been minimal and much less than what people are claiming now.” Evidence has shown that Neanderthals were driven into extinction by humans who were more efficient at finding food and multiplied at a faster rate. A previous study in 2010 suggested that interspecies liaisons near the Middle East resulted in Neanderthal genes first entering humans 70,000 years ago. Modern non-Africans share more with Neanderthals than Africans, supporting the claim that the mixing occurred when the first early humans left Africa to populate Europe and Asia. The existence of a 500,000-year-old shared ancestor that predates the origin of Neanderthals provides a better explanation for the genetic mix. Diversity within this ancestral species meant that northern Africans were more genetically similar to their European counterparts than southern Africans through geographic proximity. This likeness persisted over time to account for the overlap with the Neanderthal genome we see in modern people today. Differences between populations can be explained by common ancestry, Dr Manica said. “The idea is that our African ancestors would not have been a homogeneous, well-mixed population but made of several populations in Africa with some level of differentiation, in the way right now you can tell a northern and southern European from their looks,” she said. “Based on common ancestry and geographic differences among populations within each continent, we would predict out of Africa populations to be more similar to Neanderthals than their African counterparts – exactly the patterns that were observed when the Neanderthal genome was sequenced, but this pattern was attributed to hybridisation. “Hopefully, everyone will become more cautious before invoking hybridisation, and start taking into account that ancient populations differed from each other probably as much as modern populations do.” Northern Africans would be more similar to Europeans and ancient similarity stayed because there wasn’t enough mixing between northern and southern Africans. Population diversity, known as substructure, cant explain data on the shared genes, said David Reich, a professor of genetics at Harvard Medical School, in Boston who authored the 2010 study. We have ruled out the possibility that ancient substructure can explain all the evidence of greater relatedness of Neanderthals to non-Africans than to Africans, he added. Dr Manica said hybridisation between Neanderthals and humans can never be disproved entirely.