Note: I haven’t got time at present to go into this in depth but here are few preliminary thoughts. Below my thoughts are the press release from the researchers involved plus a couple of newspaper reports.
I have always had trouble accepting the present “out of Africa” version of the evolution of modern man because the time scales commonly put forward seem absurdly short for the very considerable differences between humans which we call races to have arisen. Taking 20 years to a generation, the 200,000 years allowed for modern man gives 10,000 generations; the 40,000 years for modern man in Europe 2,000 generations.
There is also evidence from archaeology and history of the stable nature of races. Realistic depictions of human beings go back to at least 3000BC – and perhaps twice as long if carbon 14 datings on some Egyptian artefacts are to be believed – show that racial types have been stable for at least 5,000 years . If racial types have not changed in the past 5,000 years, why should we imagine that the traditional gradualist process of evolution would have radically changed them over 40,000 or even 100,000 years?
The alternative view of human evolution is multi-evolutionary with different races evolving from earlier forms of homo in different parts of the world. That theory has attractions because it would give a much longer time span for evolution to create what we now see as races. The fly in the ointment with that theory is, geneticists tell us, that the genetic evidence across all modern humans points to a common ancestor from Africa.
The idea that there may have been breeding between Neanderthals and early modern man outside of Africa breaths new life into the regional theory, because it provides a possible explanation for the differences between Africans and the rest of humanity. If Neanderthals bred first with those in the middle East and then much later with Caucasians that might provide at least a partial explanation of racial difference between Caucasians and the other non-African racial groups because the time difference between the two interactions would give opportunity from genetic change to occur in the Neanderthal population.
More radically, if Neanderthals could breed with early modern man why not sexual interaction between other sub-species of homo and early modern man, both within and without Africa? After all hominid species earlier than Homo Sapiens were widely spread throughout Eurasia hundreds of thousands of years before the appearance of Homo Sapiens. It would be interesting to see whether any DNA sequencing could be done on them. Perhaps like the Neanderthals they would share more than 99% of their genes with modern man. It might be that if their DNA could be sequenced genes specific to them might be found in modern man in different frequencies or simply present in some racial groups and not in others.
If regular inter-breeding did occur over hundreds of thousands of years this could provide a plausible scenario for the evolution of the group differences which now distinguish the different races, something which could have a very large effect even if the inter-breeding was relatively uncommon because of the small size of the hominid population until the past few millennia. A few individuals with the inter-bred genetic mixture could send their genes down the generations to a very large number of people if that mixture was evolutionarily advantageous. Suppose in the case of Neanderthals and Cro-Magnons, the Neanderthals being better adapted to the harsh ice age climate might have improved the Cro-Magnom stock for that environment.
How primitive would a hominid have to be not to breed with modern man? The researchers claim that Neanderthal DNA is 99.7% similar to that of easy to see how breeding could take place. But what about older forms of homo? Well, consider the breeding between lions and tigers or donkeys and horses. Is it inconceivable that inter-breeding between more primitive forms of homo and Neanderthals might have taken place? Would anyone like to bet that it would be impossible to fertilise a female chimp through artificial insemination with human sperm or through in vitro fertilisation? Are humans and chimps genetically further apart than lions and tigers?
As for Neanderthals, there is a school of academic thought which thinks that if they were dressed in a suit they would be able walk without causing comment down a busy street. Bearing in mind the amazing diversity of form modern humans display, I have a sneaking suspicion they might be right. I live in central London and on several occasions I have seen a man and a woman – probably mother and son from their ages – on Euston station who are dead ringers for the classic depictions of dwarves and goblins, short squat powerful bodies, very large heads and exceptionally powerful jaw structure. It would be very easy to imagine them as Neanderthals.
The fact that specifically Neanderthal genes may form only a very small part of the modern non-African genome does not mean that it has little effect today. Genes are not equal in their significance. Think of how much DNA we share with chimps and the differences between them and us. Even a few genes might make a radical difference to non-African humans.
The modern liberal view of race is that race is a social construct and that the physical differences between races are (1) trivial and (2) biological variation within a racial group is greater than that between racial groups.
The fragility of the first liberal proposition can be seen simply by noting that differences between races are more dramatic than the differences between many closely related species of animals, for example, compare a pygmy with an archetypal Scandinavian. (If homo sapiens was viewed objectively as any other organism is viewed I doubt whether we would be classified as a species.) There are also the objective differences in physiology such as testosterone level differences and of behavioural differences such as variations in racial IQ. If we add into the mix different genetic inheritances from now extinct or absorbed forms of homo within the different racial groups the social construct argument becomes even weaker.
The second liberal proposition was shaky even before this latest research because it ignored the importance of physical racial difference in assortative mating – human beings overwhelming choose partners of the same racial type even when living in circumstances which permits frequent opportunity to choose a sexual partner of a different race. Indeed, if that was not part of the innate human template there would be no such thing as recognisable races because cross-racial breeding would erased the differences long ago. If it could be demonstrated that there are significant differences in the genotype of the various races which are due not to evolution with the modern man template but are a legacy of now extinct forms of homo the second liberal argument would be completely defunct.
Having said all that, these findings should be treated with care because (1) genetics is still a science in the academic dark ages and (2) the Neanderthal DNA has not yet be fully sequenced, (3) the sample used were heavily contaminated and (4) the number of Neanderthal remains discovered to date remain in the hundreds rather than the thousands, many of them very incomplete skeletons. None the less, a most interesting piece of research. 22 5 2010 RH