Right: Reconstruction of the appearance of a Neanderthal child from the University of Zürich, based on remains found at Gibraltar. Some representations of Neanderthals give them dark skin and monstrously thick lips, thus giving them some resemblance to the backward races that we encounter today: this is a mistake.
Neanderthal Man existed 400,000 to 30,000 years ago. The classification of Neanderthal Man is disputed, either as a separate subspecies, Homo sapiens neanderthalensis, or (more commonly) as a separate species, Homo neanderthalensis.
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| Known distribution of Neanderthal Man. |
The possibility that there was some Neanderthal admixture in modern Europeans was still discussed in the early twentieth century, but on its way toward becoming a fringe view. It seems common sense that when two anthropoid populations roam the same territory, some miscegenation will occur, if only through rape and conquest. Henry Fairfield Osborn in 1914 conceded that this was the usual course of human events, but rejected that possibility in this instance due to lack of evidence:
In the racial replacements of savage as well as of historic peoples the men are often killed and the women spared and taken into the families of the warriors, but no evidence has thus far been found that even the Neanderthal women were spared or allowed to remain in the country, because in none of the burials of the Aurignacian times is there any evidence of the crossing or the admixture of the Cro-Magnons and the Neanderthals. (Osborn, Men of the Old Stone Age (1921), p. 272)
H.G. Wells in his The Outline of History (1919), while endorsing Osborn’s view, mentions that not everyone agrees:
… it is only fair to the reader to note that many writers do not share this view. They write and speak of living “Neanderthalers” in contemporary populations. One observer in the past has written of such types in the west of Ireland; another has observed them in Greece. (Wells, The Outline of History, Vol. I (1920), p.86n)
Now, with the new technology of DNA testing, we know that Osborn’s conclusion, enshrined for a century as the mainstream view, was wrong. The Cro-Magnon conquerors did keep Neanderthal women.
Since Neanderthal Man was concentrated in Europe, it seems likely that Europeans would have by far the highest incidence of Neanderthal admixture in their racial composition. Only a few Neanderthal fossils have been found outside western and central Europe, and none have been found in Africa. The ancestors of the modern Mongoloid and Australoid races could have migrated through the fringe of Neanderthal distribution but they would not have coexisted with them for millennia as did our Cro-Magnon ancestors.
The study published in Science compared the combined DNA of three Neanderthal bones to five modern humans (including an African Negro and a Bushman). It did not find a higher incidence of Neanderthal genes in the Frenchman than in the Chinaman or New Guinean, which the authors admit is a surprising result, but they suggest that this could be due to subsequent migrations into Europe, e.g. by Alpines, whose ancestors entered Europe during the New Stone Age and are prevalent in France. In that case, there might well be pockets in Europe where the Neanderthal heritage is greater — very likely in some of the same populations where substantial persistence of the other Old Stone Age type, Cro-Magnon, is in evidence, such as among the Phalian race of Germany, or perhaps, as Wells mentions, in Greece and Ireland.
In any event, since there is no trace of Neanderthal Man in Africa, our Neanderthal heritage is an absolute distinction between us and the Negro. Neanderthal admixture may have opened evolutionary possibilities for non-African humanity that never existed in Africa.
Neanderthal Man was physically robust and highly muscular, and able to survive well in a cold climate. Neanderthal Man had the largest cranial capacity of any human type, but this was occupied largely by the cerebellum, for muscle control. Their faces are unattractive by our standards, including a prominent brow ridge, a low forehead, and a weak chin, features which we tend to associate with simplicity and servility.
It is believed, based on “rodeo” injuries found in Neanderthal skeletons, that these robust people hunted by leaping onto a large animal’s back and stabbing it. The fact that they survived their occasional broken bones from these encounters is inferred to mean that other Neanderthals cared for them while they were incapacitated.
Three-quarters of Neanderthal fossil sets found show signs of malnutrition, which implies that their methods of acquiring food for their powerful bodies were often inadequate.
While the Neanderthal had only stabbing spears, the Cro-Magnon had developed projectile weapons, including, it is believed, the bow and arrow. The failure among Neanderthals to develop such weapons was probably based on a lack of mental facility for using them, with the cerebrum, the seat of spatial reasoning, being much less developed in the Neanderthal than in the Cro-Magnon. This difference in the development of the brain is reflected in the shapes of the skulls, with Cro-Magnon having a much higher forehead to contain the highly developed cerebrum.
The mixture of such divergent types as Cro-Magnon (modern) and Neanderthal Man seems likely to have produced more negative than positive consequences, especially given that the Neanderthal type died out, but Professor John Hawks of the University of Wisconsin points out that tens of millennia of natural selection (under the harsh conditions of a northern climate) are likely to have sorted out the drawbacks, so that the ultimate overall effect of the admixture could only be positive.
“What it means is that any traits [Neanderthals] had that might have been useful in later populations should still be here.
“So when we see that their anatomies are gone, this isn’t just chance. Those things that made the Neanderthals apparent to us as a population – those things didn’t work. They’re gone because they didn’t work in the context of our population.”
Professor Hawks’ point is valid so long as the forces of natural selection are in effect. Under the aegis of civilization, however, where there is no harsh struggle for existence to weed out the unfit, where in fact we take care of our defective individuals and even allow them to reproduce, there can be no Neanderthal traits that don’t work in the context of our population. The re-emergence and spread of some unhelpful effects of the Neanderthal admixture therefore seems likely.
There is a theory that certain cognitive disorders are due precisely to the re-emergence of Neanderthal traits, including autism, lack of hand-eye coordination (dyspraxia), and seasonal affective disorder (due to an impulse to hibernate). A BBC article notes that autism is more common among Europeans, “who would be expected to have more Neanderthal genes” than other races. David Brown, a physician writing in the Washington Post, identified some specific Neanderthal genes as connected to hereditary disorders:
They include THADA (diabetes); DYRK1A (Down syndrome), NRG3 (schizophrenia) and CADPS2 (autism). One called RUNX2 is involved in deformities of the skull and collarbone — parts of the skeleton in which modern people and Neanderthals differed visibly. (Washington Post, 7 May 2010)
It could be that we and the rest of non-African humanity have received some benefit from the small admixture of Neanderthal genes in us. But at the same time, without eugenic measures, any latent negative effects of the crossing will become ever more manifest, and probably have been on the increase along with every other unhelpful hereditary trait, since the dawn of civilization.
Neanderthal genes ‘survive in us’
By Paul Rincon
Science reporter, BBC News
Many people alive today possess some Neanderthal ancestry, according to a landmark scientific study.
The finding has surprised many experts, as previous genetic evidence suggested the Neanderthals made little or no contribution to our inheritance.
The result comes from analysis of the Neanderthal genome – the “instruction manual” describing how these ancient humans were put together.
Between 1% and 4% of genomes of people in Eurasia come from Neanderthals.
But the study confirms living humans overwhelmingly trace their ancestry to a small population of Africans who later spread out across the world.
“ [Neanderthals] are not totally extinct, in some of us they live on – a little bit ”
Professor Svante Paabo Max Planck Institute for Evolutionary Anthropology
The most widely-accepted theory of modern human origins – known as Out of Africa – holds that the ancestors of living humans ( Homo sapiens ) originated in Africa some 200,000 years ago.
A relatively small group of people then left the continent to populate the rest of the world between 50,000 and 60,000 years ago.
While the Neanderthal genetic contribution – found in people from Europe, Asia and Oceania – appears to be small, this figure is higher than previous genetic analyses have suggested.
“They are not totally extinct. In some of us they live on, a little bit,” said Professor Svante Paabo, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
Professor Chris Stringer, research leader in human origins at London’s Natural History Museum, is one of the architects of the Out of Africa theory. He told BBC News: “In some ways [the study] confirms what we already knew, in that the Neanderthals look like a separate line.
“But, of course, the really surprising thing for many of us is the implication that there has been some interbreeding between Neanderthals and modern humans in the past.”
John Hawks, assistant professor of anthropology at the University of Wisconsin-Madison in the US, told BBC News: “They’re us. We’re them.
“It seemed like it was likely to be possible, but I am surprised by the amount. I really was not expecting it to be as high as 4%,” he said of the genetic contribution from Neanderthals.
The sequencing of the Neanderthal genome is a landmark scientific achievement, the product of a four-year-long effort led from Germany’s Max Planck Institute but involving many other universities around the world.
The project makes use of efficient “high-throughput” technology which allows many genetic sequences to be processed at the same time.
The draft Neanderthal sequence contains DNA extracted from the bones of three different Neanderthals found at Vindija Cave in Croatia.
Retrieving good quality genetic material from remains tens of thousands of years old presented many hurdles which had to be overcome.
The samples almost always contained only a small amount of Neanderthal DNA amid vast quantities of DNA from bacteria and fungi that colonised the remains after death.
The Neanderthal DNA itself had broken down into very short segments and had changed chemically. Luckily, the chemical changes were of a regular nature, allowing the researchers to write software that corrected for them.
Writing in Science journal, the researchers describe how they compared this draft sequence with the genomes of modern people from around the globe.
“The comparison of these two genetic sequences enables us to find out where our genome differs from that of our closest relative,” said Professor Paabo.
“ Those things that made the Neanderthals apparent to us as a population – those things didn’t work ”
Dr John Hawks University of Wisconsin-Madison
The results show that the genomes of non-Africans (from Europe, China and New Guinea) are closer to the Neanderthal sequence than are those from Africa.
The most likely explanation, say the researchers, is that there was limited mating, or “gene flow”, between Neanderthals and the ancestors of present-day Eurasians.
This must have taken place just as people were leaving Africa, while they were still part of one pioneering population. This mixing could have taken place either in North Africa, the Levant or the Arabian Peninsula, say the researchers. [This is a valid assumption only for those populations that did not end up in Europe. – Hadding]
The Out of Africa theory contends that modern humans replaced local “archaic” populations like the Neanderthals.
But there are several variations on this idea. The most conservative model proposes that this replacement took place with no interbreeding between modern humans and Neanderthals.
Unique features
Another version allows for a degree of assimilation, or absorption, of other human types into the Homo sapiens gene pool.
The latest research strongly supports the Out of Africa theory, but it falsifies the most conservative version of events.
The team also identified more than 70 gene changes that were unique to modern humans. These genes are implicated in physiology, the development of the brain, skin and bone.
The researchers also looked for signs of “selective sweeps” – strong natural selection acting to boost traits in modern humans. They found 212 regions where positive selection may have been taking place.
The scientists are interested in discovering genes that distinguish modern humans from Neanderthals because they may have given our evolutionary line certain advantages over the course of evolution.
The most obvious differences were in physique: the muscular, stocky frames of Neanderthals contrast sharply with those of our ancestors. But it is likely there were also more subtle differences, in behaviour, for example.
Dr Hawks commented that the amount of Neanderthal DNA in our genomes seemed high: “What it means is that any traits [Neanderthals] had that might have been useful in later populations should still be here.
“So when we see that their anatomies are gone, this isn’t just chance. Those things that made the Neanderthals apparent to us as a population – those things didn’t work. They’re gone because they didn’t work in the context of our population.”
Researchers had previously thought Europe was the region where Neanderthals and modern humans were most likely to have exchanged genes. The two human types overlapped here for some 10,000 years.
The authors of the paper in Science do not rule out some interbreeding in Europe, but say it was not possible to detect this with present scientific methods.