Neanderthals may have interbred with humans Genetic data points to ancient liaisons between species. Rex Dalton
Archaic humans such as Neanderthals may be gone but they're not forgotten — at least not in the human genome. A genetic analysis of nearly 2,000 people from around the world indicates that such extinct species interbred with the ancestors of modern humans twice, leaving their genes within the DNA of people today.
The discovery, presented at the annual meeting of the American Association of Physical Anthropologists in Albuquerque, New Mexico, on 17 April, adds important new details to the evolutionary history of the human species. And it may help explain the fate of the Neanderthals, who vanished from the fossil record about 30,000 years ago. "It means Neanderthals didn't completely disappear," says Jeffrey Long, a genetic anthropologist at the University of New Mexico, whose group conducted the analysis. There is a little bit of Neanderthal leftover in almost all humans, he says.
The researchers arrived at that conclusion by studying genetic data from 1,983 individuals from 99 populations in Africa, Europe, Asia, Oceania and the Americas. Sarah Joyce, a doctoral student working with Long, analyzed 614 microsatellite positions, which are sections of the genome that can be used like fingerprints. She then created an evolutionary tree to explain the observed genetic variation in microsatellites. The best way to explain that variation was if there were two periods of interbreeding between humans and an archaic species, such as Homo neanderthalensis or H. heidelbergensis.
"This is not what we expected to find," says Long.
Using projected rates of genetic mutation and data from the fossil record, the researchers suggest that the interbreeding happened about 60,000 years ago in the eastern Mediterranean and, more recently, about 45,000 years ago in eastern Asia. Those two events happened after the first H. sapiens had migrated out of Africa, says Long. His group didn't find evidence of interbreeding in the genomes of the modern African people included in the study.
The researchers suggest that the population from the first interbreeding went on to migrate to Europe, Asia and North America. Then the second interbreeding with an archaic population in eastern Asia further altered the genetic makeup of people in Oceania.
The talk at the anthropology meeting caught the attention of many researchers, some of whom have been trying to explain puzzling variations in the human genome. "They are onto something," says Noah Rosenberg, an anthropological geneticist at the University of Michigan in Ann Arbor, who heard the talk.
A test of the New Mexico team's proposals may come soon. Svante Pääbo and colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, announced early last year that they had finished sequencing a first draft of the Neanderthal genome, and they are expected to publish their work in the near future. Pääbo's earlier studies on components of Neanderthal genomes largely ruled out interbreeding, but they were not based on more comprehensive analyses of the complete genome.
Linda Vigilant, an anthropologist at the Planck Institute, found Joyce's talk a convincing answer to "subtle deviations" noticed in genetic variation in the Pacific region.
"This information is really helpful," says Vigilant. "And it's cool."
The paleontological record also is producing fossils that complement such interbreeding theories. Pääbo's team and Russian colleagues recently reported the mitochondrial genome of an archaic human from the Altai Mountains — in southern Siberia near ancient Asian trade routes
1.
The ancient mitochondrial DNA came from a piece of finger bone, which the groups haven't identified by species. It could be Neanderthal, a new Homo species or some other archaic form — like H. erectus, who spread to Oceania by 1.8 million years ago.
The Pääbo team reported that the bone was from an individual that lived 30,000–48,000 years ago in Denisova Cave, near where both modern humans and Neanderthals then dwelled. But the age of the bone has been questioned by researchers, who say the cave's sediments may have been reworked, making the bone's layer older.
At the anthropology meeting, Theodore Schurr, a molecular anthropologist at the University of Pennsylvania in Philadelphia, said the genetic model showing interbreeding raises questions about the range of species, like H. heidelbergensis. He noted that human skeletons found at Lake Mungo in New South Wales, Australia, have robust features, which may represent the result of interbreeding; they are dated to more than 20,000 years ago.
Keith Hunley, another member of the New Mexico group, said the team is now moving to publish its results in the near future.
References Comments to this article have been posted below, however links and names of posters have been removed (Narayanjot Kaur)
#10186
I have always wondered if Basques, which are known to have striking differences in the frequency of blood groups and the form of the skull from the rest of the european population could not be such a population. I do not mean to be offensive in anyway...just curious to know whether any study has been done in that direction
#10187
I have always wondered if Basques, which are known to have striking differences in the frequency of blood groups and the form of the skull from the rest of the european population could not be such a population. I do not mean to be offensive in anyway...just curious to know whether any study has been done in that direction
#10188
An Indian researcher named Eswaran came up with a mechanism which can highly restrict gene flow to a group like modern humans even when interbreeding occurs. Suupose that there are a number of genetic allelles which together confer an advantage, and where that advantage is lost or highly muted if even one of the allelles is lost. In that case, any interbreeding results in disadvantaged children (or even a disadvantaged group). This does not stop gene transfer, but keeps it very limited. This result sounds like it is in keeping with Eswaran's research. -- Beyond that, I would like to see nuclear DNA studies of the Neanderthals and the Denisova remains showing that they held these anomolous sequences. After all, it is easy to speculate.
#10246
This is great. If proven correct we might have on our hands the beginning of the process to unravel the mystery of human diversity! very interesting that modern Africans do not have Neanderthal genes.
#10267
From the distribution of fuzzy faced humans (Europeans, Ainu, Australians, and, I think it will be found, some in isolated parts of Africa) around a core population of bare faced humans, we might have guessed that 'modern humans' spread from some center and only 'hybridized' at the fringes where the more archaic populations managed to hold out the longest. It seems fairly clear to me that the key mutation that created 'modern humans' was something that resulted in the loss of the adult male beard. In most animal species with distinctive juvenile and adult forms, the change from juvenile to adult entails a social change from protective family to aggressive competition. I would guess that the social group for archaic humans (Neanderthals, etal.) was rather like that of lions and there was very little male social structure and hence the long stasis of the male tool kit — the hand axe, period.
Males did not teach their male heirs how to work stone but rather drove them out of the family pride at sexual maturity. With the loss of the beard, the sign of male sexual maturity, the modern male subversives could hang around camp much longer, do some sneaky breeding under the nose of the harem 'master', and eventually learn to practice male cooperation to form gangs to throw the old bearded male out. With the formation for the first time of genuine male culture, the 'modern human' population exploded and quickly replaced its predecessor. If we search we may yet find, to match the 'mitochondrial Eve' evidence for her mate, the 'bare faced Adam' I think.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/scitech/30801-neanderthals-may-have-interbred-with-humans.html
#10274
The baske people seems not being too different from a genetic point of view to other european populations, inbreeding may explain most of baske singularities. The baske language is a different issue, some UCM researches published a report entitled "Egyptians, bereberes, guanches and baskes" linking all those cultures. One of my grandmothers, having an H3 haplogroup mtDNA, had some Neanderthal features, as she had prominent superciliar arches, and unwanted trait for women in the spanish culture, and one of his cousins was the first in writing a baske language grammar. My other grandmother is mtDNA haplogroup K,but born in Vizcaya, and my only grandfather studied has an R1b1c Y chromosome, mixing has always had an important role all over Europe. I was once told about a village of Berebere origin in Seville, having Rh neg blood. When a bus line was opened connecting them to a village of different ethnic background, Rh isoimmunizations began to appear. In many rural places of Spain you find people having several repeated surnames, as they married cousins because of the obstacles connected to mating out of the place. Regarding the Neanderthal subject, it seems that some roman historians registered the presence of people of an specially robust and primitive body traits working in the roman mines.
#10429
Sadly, many of us inquisitive people do not still have a clue as to where we came from and where we are going! Thus this study is interesting, as it demonstrates some progress in the science of human evolution. Though in my opinion it provides no concrete evidence for the precise origin of man.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=30801
Nevertheless, from a purely academic angle this is an interesting piece of research. Evidently, this paper contradicts several earlier mitochondrial DNA based studies including those by Giorgio Bertorelle and co-workers (1) which indicated that early modern humans and Neanderthals probably did not interbreed. Moreover, it must be added that often these studies have been plagued with problems, as the Neanderthal DNA was frequently found to be contaminated with DNA from modern humans.
Also it is quite likely that the Neanderthals did venture into some regions of Africa, as Neanderthal remains have been found close to Africa (for example in Israel). It is thus necessary that a detailed study of the African populations also be undertaken.
Moreover, since the Out of Africa Model of the Origin of Man is on shaky grounds (as it seems to be politically driven and also several older humanoid fossils have been found particularly in Asia) one should look further into the early humanoid fossils such as those from Dmanisi (about 1.8 million years old), Georgia etc.
1) PNAS May 27, 2003 vol. 100 no. 11 6593-6597
#10440
In relation to the comment posted by Upinder Fotadar.
I'm not an expert in mitochondrial DNA, but I know it moves from generation to generation following the maternal line. So, if modern humans do not show any ancient mitochondrial DNA it does not necessarily mean that modern humans and Neanderthal did not interbreed. We could speculate that interbreeding DID actually happen, but only between Neanderthal men and modern women, although such a sex bias would not necessarily find any explanation plausible. Still, it could be an interesting possibility.
#10551
All the trail of mitochondrial DNA shows is the maternal line of inheritance. The maternal line could have died out and the paternal lines continued on. The genes of Neandertal women live on in our genes and the genes of their male descendants.
Many of the traits that differentiated Neandertal from modern humans were inherited reponses to brutally cold climate of Ice Age Europe. Therefore I don't think people of African descent should feel slighted by this study, I am sure that we will find that the African cousins of Neandertal live on in their genes. Research in the coming years will probably find this as the African fossils are sequenced.
Neanderthals may have interbred with humans : Nature News 
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