Cheap shots and collateral damage

Ségolène Royal and supporters

A University of New Mexico research team has announced that the human gene pool seems to have admixture from an outside source, most likely from the Neanderthals and other archaic humans. This conclusion was based on analysis of variation in microsatellite DNA from European, Asian, and Oceanic populations. Since microsatellite DNA is thought to be of neutral selective value, any variation must be due to the slow gradual accumulation of new mutations or admixture from outside our gene pool.

The researchers pinpointed two admixture events:

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. (Dalton, 2010)

This analysis suffers from several problems. For one thing, it is based on rough estimates, i.e., the length of time that modern humans have existed outside Africa and the speed at which new mutations accumulate in microsatellite DNA. There is also the dubious assumption that this DNA is never affected by natural selection.

Nonetheless, this announcement has delighted anthropologists like John Hawks, Greg Cochran, and Alan Templeton who have long argued against the ‘Out of Africa’ model of human origins. As multiregionalists, they used to argue that modern humans evolved out of earlier archaic populations in Africa, Europe, and Asia. Thus, modern Europeans would primarily be descended from Neanderthals, Modern Asians from Peking man, and so on.

Today, the multiregional model is no longer accepted, and its proponents are now backing a compromise. Modern Europeans, for instance, would largely descend from the wave of humans that spread out of Africa 60,000 to 40,000 years ago, but they would still have some admixture from Neanderthals in their gene pool.

Will this debate ever be settled? Yes, and very soon. That’s the good news. In a few months, the reconstruction of the Neanderthal genome will be published. By comparing it with the genome of modern Europeans, we should find out whether any genes flowed from one to the other. Preliminary comparisons have already been done and to date have found … nothing.

Now the bad news. The triumph of the ‘Out of Africa’ model will be heavily politicized. Although I support this model, I feel nothing but shame for the cheap shots that many other adherents have made. A common one has been to cast multiregionalists as ‘racists.’

This name-calling appears in a New York Times article that presents multiregionalists as “inheritors of a culturally infected biology” and its opponents as “supporting our better inclinations.” In an interview, paleontologist Chris Stringer clearly enjoyed being on the side of the angels, while snidely accusing the other side of racism. He recalled an encounter with Carleton Coon in a Harvard washroom where the aged professor referred to one of his critics as ''that . . . Jew Weiner.''

What irks me about this anecdote is not that it is unverifiable (washroom conversations are not published and Coon has long been dead), but simply its irrelevance. Suppose it could be shown that Carleton Coon had regularly sodomized his grad students. Or would microwave live kittens. Or had bad breath. What would that prove or disprove about the multiregional model? Nothing. This is ad hominem at its sleaziest.

In the same interview, Stringer went on to say that our species is so young that differences among humans can only be skin-deep:

Since so little time has passed since they [modern humans] decamped from Africa, dispersing to the far regions of the world -- 100,000 years being a mere paleontological moment -- ''only slight differences, if any, in intellect and innate behavior are likely to have evolved between modern human populations.'' We are ''all Africans under our skin.''

Uh, 100,000 years is not a mere paleontological moment. A population can undergo significant physical and genetic change in as little as eight generations. In fact, many animal species go back only to the last ice age (25,000-10,000 BP). Evolutionary change is due primarily to the intensity of natural selection and only secondarily to the passage of time. Indeed, the faster such change has occurred, the more important it must be, since it is being driven by intense natural selection and not by adaptively neutral processes like genetic drift or founder effects.

I can forgive journalists for not knowing the above. I find it harder to forgive Chris Stringer, who is fully aware of how fast natural selection can operate. There is no point in winning a debate if you inflict a lot of collateral damage in the process.

Clearly, there has been collateral damage. The catch phrase “We are all Africans” has taken on a life of its own, with almost 100,000 Google hits. In the last French election, Ségolène Royal cited the latest findings in paleontology when she proclaimed, “Nous sommes tous des Africains!” This cute expression is even appearing in high school textbooks.

And we’ll probably see it in newspaper headlines when the Neanderthal genome is finally published.

References

Dalton, R. (2010). Neanderthals may have interbred with humans. Genetic data points to ancient liaisons between species. Naturenews, April 20.
http://www.nature.com/news/2010/100420/full/news.2010.194.html

Hawks, J. (2010). Multiregional evolution lives! John Hawks Weblog, April 21
http://johnhawks.net/weblog/reviews/evolution/introgression/joyce-dalton-interbreeding-2010.html

Richards, R.J. (1997). Neanderthals need not apply, New York Times, August 17, 1997.
http://www.nytimes.com/books/97/08/17/reviews/970817.17richart.html

The puzzle of European hair and eye color

I’ve been fascinated by a puzzle of modern human evolution: the diverse palette of hair and eye colors that has developed in some populations (Frost, 2006; Frost 2008). Hair may be black, brown, flaxen, golden, or red, and eyes may be brown, blue, gray, hazel, or green. Both polymorphisms are largely confined to Europeans, especially those from the north and east.

This is an evolutionary puzzle for several reasons:

1. Hair color and eye color diversified through two separate processes that involved several gene loci (principally at MC1R for hair color and at OCA2-HERC2 for eye color).

2. Both processes occurred within the same geographic area.

3. Both processes occurred within a relatively narrow time frame, i.e., after the arrival of modern humans in Europe c. 35,000 years ago. Current estimates place this evolutionary change quite late in time, perhaps during the last ice age (25,000 - 10,000 BP).

For some anthropologists, this palette of hair and eye colors is a side effect of the lighter skin of Europeans. This lighter skin is, in turn, due to relaxation of selection for dark skin at non-tropical latitudes and a resulting accumulation of ‘loss of function’ alleles that affect not only skin color but also hair and eye color.

Yet relaxation of selection could not have produced so many new alleles over so little time. If selection is relaxed at loci for hair and eye color, close to a million years must elapse to produce the hair- and eye-color variability that Europeans now display, including ~ 80,000 years for the current prevalence of red hair alone (Harding et al., 2000; Templeton, 2002). This is much longer than the c. 35,000 years that modern humans have been in Europe. Moreover, the presumed initial cause—the whitening of European skin—seems to have occurred long after the arrival date of 35,000 BP (Norton & Hammer, 2007). As a Science journalist commented: “the implication is that our European ancestors were brown-skinned for tens of thousands of years” (Gibbons, 2007).

The puzzle is not resolved if Europeans turned white because of positive selection for lighter skin, as opposed to relaxation of selection for darker skin. Such a scenario would not have caused hair and eye color to diversify. In fact, most of the new alleles have little or no relationship with skin color. Only red hair and blue eyes are visibly associated with lighter skin.

There must have been positive selection for diversity of hair and eye color in and of itself. And this selection must have been very strong, given the relatively narrow time frame.

I have suggested that the likeliest explanation is sexual selection (Frost, 2006; Frost, 2008). This kind of explanation is consistent with several general facts:

1. Sexual selection typically creates brightly colored traits.

2. Such traits tend to be on or close to the face, because this part of the body attracts the most visual attention.

3. Intense sexual selection can produce color polymorphisms.

But why would sexual selection have been stronger among northern and eastern Europeans than among other human populations? To answer this question, we must understand why sexual selection should have differed in intensity among ancestral modern humans. In general, the differences were latitudinal, i.e., sexual selection differed primarily along a north-south axis.

Latitudinal differences in the ratio of men to women on the mate market

In the tropical zone, a woman could gather or grow enough food for herself and her children with little assistance. Because the cost of providing for a second wife was very low (often negative, i.e., a net gain), a man’s optimal reproductive strategy was to have as many wives as possible. There were thus too many men competing for too few women.

The farther away ancestral humans were from the tropics, the more women needed food (meat) provided by men. This was especially so in winter, when opportunities for food gathering were scarce. The cost of providing for a second wife was thus high, making polygyny impossible for all but the ablest hunters.

Alongside this trend of increasing female dependence on male providers was another north-south trend: male mortality increased farther away from the tropics because of longer hunting distances and the resulting increased risk of death due to accidents, exposure, starvation, etc.

Continental Arctic: optimal conditions for sexual selection of women

These two trends culminated in the continental Arctic. Here, women had few opportunities for food gathering at any time of year. They and their children depended almost wholly on meat that men provided through hunting. Here too, hunting distance was at a maximum. Men hunted wandering herds of herbivores, mainly reindeer, over very long distances. The high rate of male mortality, combined with the low rate of polygyny, limited the number of males available for mating. Result: a corresponding surplus of unmated females and intense sexual selection of women.

Today, this kind of environment is confined to the northern fringes of Eurasia and North America, but during the last ice age (25,000 – 10,000 BP) it lay further south and covered more territory. This was especially so in Europe, where the Scandinavian icecap had pushed the steppe-tundra zone down to the plains stretching from southwestern France through northern Germany and into eastern Europe. These temperate latitudes permitted a high level of bioproductivity and a comparatively large human population—the ancestors of today’s Europeans.

Sexual selection and color traits

When sexual selection is weak, the adaptive equilibrium is dominated by selection for a dull, cryptic appearance that reduces detection by predators. As sexual selection grows stronger, the equilibrium shifts toward a more noticeable appearance that retains the attention of potential mates, typically by means of vivid and/or novel colors.

One outcome may be a polymorphism of brightly colored phenotypes, due to the pressure of selection shifting to scarcer and more novel hues whenever a color variant becomes too common. This frequency dependence has been shown in humans. Thelen (1983) presented male participants with slides showing attractive brunettes and blondes and asked them to choose, for each series, the woman they would most like to marry. One series had equal numbers of brunettes and blondes, a second 1 brunette for every 5 blondes, and a third 1 brunette for every 11 blondes. Result: the rarer the brunettes were in a series, the likelier any one brunette would be chosen.

Among ancestral Europeans, this selection pressure may have caused a proliferation of new hair and eye colors to the detriment of our species norm of black hair and brown eyes. The selection was partly for novel colors. A rare color engages visual attention for a longer time than does a more common color (Brockmole & Boot, 2009). It may be that color rarity stimulates a mental algorithm that scans the visual environment for new or unusual objects.

In addition to color novelty, there also seems to have been selection for color brightness. Hair is carrot-red but not burgundy red. Eyes are light blue but not navy blue. Maan and Cummings (2009) argue that brighter colors have a stronger impact because they deliver a stronger signal that is more readily learned and retained in memory.

In a mate market already saturated with high-quality females, these eye-catching characteristics—color novelty and color brightness—may have made the difference between success and failure in finding a mate.

Other evidence for unusually strong sexual selection of European women

Hair and eye color polymorphism coincide geographically with other unusual physical traits. There is, for instance, the extreme whitening of the skin, which we do not see in other human populations at similar latitudes and which may have been driven by male targeting of lighter skin as a female-specific characteristic.

There also seems to have been selection to accentuate female-specific traits. Women of European descent have wider hips, narrower waists, and thicker deposition of subcutaneous fat than do women of other geographic origins (Hrdlička, 1898; Meredith & Spurgeon, 1980; Nelson & Nelson, 1986). Even before birth, Euro-American fetuses show significantly more sexual dimorphism than do African-American fetuses (Choi & Trotter, 1970).

In the same vein, Liberton (2009) has found that face shape differentiated between Europeans and sub-Saharan Africans in part through a selective force that has acted primarily on women, and not on both sexes. This too would be consistent with the selection pressure that seems to have diversified European hair and eye color.

References

Brockmole, J.R. & W.R. Boot. (2009). Should I stay or should I go? Attentional disengagement from visually unique and unexpected items at fixation, Journal of Experimental Psychology, 35, 808-815.

Choi, S.C., & Trotter, M. A. (1970). Statistical study of the multivariate structure and race‑sex differences of American White and Negro fetal skeletons. American Journal of Physical Anthropology, 33, 307‑312.

Frost, P. (2008). Sexual selection and human geographic variation, Proceedings of the 2nd Annual Meeting of the NorthEastern Evolutionary Psychology Society, The Journal of Social, Evolutionary & Cultural Psychology, 2 (supp.), 49-65, www.jsecjournal.com/NEEPSfrost.pdf

Frost, P. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior, 27, 85-103 http://www.sciencedirect.com/science/journal/10905138

Gibbons, A. (2007). American Association Of Physical Anthropologists Meeting: European Skin Turned Pale Only Recently, Gene Suggests. Science 20 April 2007: 316. no. 5823, p. 364 DOI: 10.1126/science.316.5823.364a http://www.sciencemag.org/cgi/content/summary/316/5823/364a

Harding, R.M., Healy, E., Ray, A.J., Ellis, N.S., Flanagan, N., Todd, C., Dixon, C., Sajantila, A., Jackson, I.J., Birch‑Machin, M.A., & Rees, J.L. (2000). Evidence for variable selective pressures at MC1R. American Journal of Human Genetics, 66, 1351‑1361.

Hrdlička, A. (1898). Physical differences between White and Colored children. American Anthropologist, 11, 347‑350.

Liberton, D.K., K.A. Matthes, R. Pereira, T. Frudakis, D.A. Puts, & M.D. Shriver. (2009). Patterns of correlation between genetic ancestry and facial features suggest selection on females is driving differentiation. Poster #326, The American Society of Human Genetics, 59th annual meeting, October 20-24, 2009. Honolulu, Hawaii.

Maan, M.E. & M.E. Cummings. (2009). Sexual dimorphism and directional sexual selection on aposematic signals in a poison frog, Proceedings of the National Academy of Sciences (USA), 106, 19072-10977.

Meredith, H.V., & Spurgeon, J.H. (1980). Somatic comparisons at age 9 years for South Carolina White Girls and girls of other ethnic groups. Human Biology, 52, 401‑411.

Nelson, J.K., & Nelson, K.R. (1986). Skinfold profiles of Black and White boys and girls ages 11‑13. Human Biology, 58, 379‑390.

Norton, H.L. & Hammer, M.F. (2007). Sequence variation in the pigmentation candidate gene SLC24A5 and evidence for independent evolution of light skin in European and East Asian populations. Program of the 77th Annual Meeting of the American Association of Physical Anthropologists, p. 179.

Templeton, A.R. (2002). Out of Africa again and again. Nature, 416, 45-51.

Thelen, T.H. (1983). Minority type human mate preference. Social Biology, 30, 162-180.

Population replacement in Algeria?

'Trans-Saharan' immigrant camp in Algeria

The 21st century will see a surge of emigration from sub-Saharan Africa that will eclipse the one that used to pour out of Europe into the Americas, southern Africa, Siberia, and Australia. Millions upon millions will be claiming new lands for themselves, just like Europeans of another age.

The biggest surprise will be their push into a wide range of territories, and not simply the homelands of the former colonial powers. Remember, this is not a game of ‘tit for tat.’ It is not some kind of just recompense for colonial wrongs, although its enablers will portray it as such. This is a game that predates our notions of justice and even humanity itself. In fact, it is as old as the oldest life forms.

One front of this population expansion will be Algeria, a Mediterranean country immediately north of sub-Saharan Africa. Until recently, it was a country of emigration, not immigration, its population growing almost entirely through natural increase. The last decade, however, has seen its demography become more and more ‘European’. On the one hand, the fertility rate has fallen to 2.27 children per woman—just enough to replace the existing population. On the other, immigration has become a significant source of population growth.

The current influx began in the mid-1990s. Initially, it flowed into the Saharan portion of Algeria from the neighboring states of Niger and Mali. Over the past decade, its sources have broadened to include all of West Africa and even Central and East Africa. This ‘trans-Saharan’ immigration is also spreading to the north of the country, i.e., the Mediterranean coast:

Further north, in Alger, between the migrants in the old Arab city (the Casbah), the old colonial center (the Port-Saïd quarter essentially), and those in the peripheral quarters (Dely Brahim, Chéraga), and even though the migrants keep a very low profile, there are at least 15,000. In Oran, Algeria’s western metropolis, though closer to the border, there are several thousand (between 3,000 and 5,000) whereas for Maghniyya, a town next to northern Morocco, […] the member of the legislative assembly for that town gives a figure of 3,000 migrants in a camp nearby (Oued Jordi) and 4,000 others in the town itself. (Bensaâd, 2009)

This is something new for Algerians:

The phenomenon of clandestine immigration in Algeria is relatively new for a country like our own, which has become, in only a few years, one of the desirable destinations for nationals of sub-Saharan countries, with some of them attempting to settle here. (Algerie-dz.com, 2005)

At first, it was thought that they were simply passing through on their way to Europe. Many were, but many more saw Algeria itself as their new home:

Some might think that these Black African immigrants are just passing through Algeria, while they wait to find a way to enter Europe. But in reality they say they have found what they want in Algeria. As proof, they have moved in with their families. (Algerie-dz.com, 2005)

Last year, the national gendarmerie estimated that 70% of all clandestine immigrants intend to settle in the country permanently (Algerie360.com, 2009).

Efforts are certainly being made to control the influx. Bensaâd (2009, p. 18) reports that 3,000 migrants are being expelled per month at Tin Zouatin, on the Mali border. And Tin Zouatin is just one of three ‘expulsion points.’ Even though Algeria has signed all of the international conventions on refugees, it has never granted anyone refugee status (Bensaâd, 2009, p. 20)

Yet the influx continues and anti-immigration sentiment is rising among Algerians. It is unclear, however, how this sentiment will translate into political action. The current administration is committed, at least superficially, to a paradigm that took shape during the independence struggle of the early 1960s, i.e., international socialism, pan-Africanism, and Third Worldism. There is a political opposition—the Islamists—but they too are committed to a universalist paradigm that could hardly be used to mobilize opposition to immigration. Remember, most of the trans-Saharan immigrants are also Muslims.

Algeria is thus caught in an ideological gridlock that will probably allow the influx to continue, at least for now. Will we eventually see population replacement? Such a scenario might seem unlikely. After all, Algeria’s fertility rate has not fallen below the replacement level and its gendarmerie has shown a degree of seriousness in dealing with clandestine immigration that would put many Western countries to shame.

Against this, it should be pointed out that the fertility rate has already fallen below replacement in neighboring Tunisia (1.84 children per woman), and this decline will likely spread to the rest of North Africa. Meanwhile, immigration cannot help but increase. First, there is the long porous border with sub-Saharan Africa, particularly with those regions that now have the highest rates of natural increase on the continent. Second, production of oil and natural gas will spur economic growth and create employment for immigrant workers. Third, the Algerian leadership is committed to maintaining at least an outward show of pan-African solidarity. This might explain the secrecy that seems to surround most immigration data (Bensaâd, 2009, pp. 17-21). Too much information could inflame public opinion or, as the demographer Ali Bensaâd puts it, force the Algerian authorities to address “a new societal reality for which they have no legal and social answers.”

So, yes, if current trends continue, we will eventually see population replacement. This process will be fueled not only by high levels of African immigration but also by the youthful age structure and high fertility of the immigrant population, which may pass the one-million mark as soon as five years from now. At that point, immigration control will start to break down, with clandestine immigrants simply melting away into the existing community. Algeria too will be entering the “age of interesting times.”

References

Algerie-dz.com (2005). L’Algérie, eldorado de l’immigration clandestine, Sept. 6, 2005
http://www.algerie-dz.com/article3318.html

Algerie360.com (2009). Immigration clandestine : En Algérie, 70% des clandestins se stabilisent, June 2, 2009 http://www.algerie360.com/algerie/immigration-clandestine-en-algerie-70-des-clandestins-se-stabilisent/

Bensaâd, A. (2009). Le Maghreb à l’épreuve des migrations subsahariennes. Immigration sur émigration, Paris : Éditions Karthala.

Comparing Neanderthal and modern human DNA

First graph: Distributions of Pairwise Sequence Differences among Humans, the Neanderthal, and Chimpanzees. X axis = number of sequence differences; Y axis = percent of pairwise comparisons. (Krings et al, 1997).

Second graph: Green: human/human comparisons; Red: human/Neanderthal comparisons; Blue: human/chimp comparisons. X axis = number of sequence differences; Y axis = fraction of pairwise comparisons. (Green et al. 2008)

Did the Neanderthal gene pool overlap with the modern human gene pool? In other words, are some modern humans genetically closer to some Neanderthals than they are to other modern humans?

The answer is ‘yes’ if we look at individual DNA sequences, as shown in the first graph (above):

Thus, the largest difference observed between any two human sequences was two substitutions larger than the smallest difference between a human and the Neandertal. In total, 0.002% of the pairwise comparisons between human mtDNA sequences were larger than the smallest difference between the Neandertal and a human (Krings et al., 1997)

It may be noted that a small fraction (0.037%) of the inter-human comparisons are larger than the smallest distance (29 substitutions) between the Neandertal and humans. (Krings et al., 1999)

We see the same genetic overlap among present-day human populations. Some Danes seem to be closer to some Congolese than to other Danes. But this overlap disappears when we compare more than one DNA sequence at the same time. The more sequences we compare simultaneously, the less overlap there is (Risch et al., 2002; Sesardic, 2010).

We can likewise eliminate the overlap between Neanderthals and modern humans if we use the entire mtDNA genome to compare these two populations:

In 2008, the first complete sequencing of Neandertal mtDNA was announced (Green et al. 2008). A complete mtDNA genome of 16,565 base pairs was extracted from a 38,000 year old fossil from the Vindija cave in Croatia. As Krings et al. 2007 had done, the authors created a graph showing the numbers of base pair differences for humans, chimps and the Neandertal when compared against humans. Because they were able to compare across the whole genome rather than a small portion of it, the differences between humans and the Neandertal was far more striking (Fossil Hominids)

This may be seen in the second graph (above).

But why must we compare entire genomes to make the overlap go away? Why should there be any genetic overlap between two populations for any stretch of DNA if the same populations show absolutely no visual overlap to our lying eyes? What’s going on here?

The underlying reason is that most of the genome has little selective value. So the selection pressure on that DNA is pretty much the same in any population, be it Congolese, Danish, or Neanderthal. Of course, once two populations become reproductively isolated, i.e., when they become different species, their DNA will start to drift apart even at genes of low selective value (because of differing patterns of random mutations). But this divergence is very slow. Consequently, it is hard to distinguish between related species that have diverged from each other only over the last 40,000 years. This is why Neanderthals and modern humans still have some overlap, even though their last common ancestor lived over 400,000 years ago.

References

Fossil Hominids: mitochondrial DNA,

http://www.talkorigins.org/faqs/homs/mtDNA.html

Green, R., A-S. Malaspinas, J. Krause, A. Briggs, et al. (2008). A complete Neandertal mitochondrial genome sequence determined by high-throughput sequencing, Cell, 134, 416-426.

Krings, M., H. Geisert, R.W. Schmitz, H. Krainitzki, & S. Pääbo. (1999). DNA sequence of the mitochondrial hypervariable region II from the Neandertal type specimen, Proc. Nat. Acad. Sci. USA, 96, 5581-5585.

Krings, M., A. Stone, R.W. Schmitz, H. Krainitzki, M. Stoneking, & S. Pääbo. (1997). Neandertal DNA sequences and the origin of modern humans, Cell, 90, 19-30.

Risch, N., E. Burchard, E. Ziv, & H. Tang. (2002). Categorization of humans in biomedical research: genes, race and disease, Genome Biol, 3, 1-12.

Sesardic, N. (2010). Race: a social destruction of a biological concept, Biol. Philos, 25, 143-162.

Homo altaiensis?

(see Coleman, 2010)

About 80,000 years ago in East Africa, some human populations began to expand rapidly at the expense of others. This process culminated in a massive expansion that started spreading to other continents some time after 60,000 BP (Watson et al., 1997).

This population expanded at the expense of more archaic humans. In Europe at least, there was initially some sort of cultural contact between the two groups, perhaps trade. But the modus vivendi did not last. All of the archaic humans went extinct and now exist only in bone fragments. They lost out in the struggle for existence.

In recent years, researchers have breathed new life into these old bones by retrieving mtDNA and even nuclear DNA from them. This retrieval is well under way with respect to the European Neanderthals. We should soon have a full reconstruction of their genome and, eventually, a good idea of what they looked like and perhaps how they felt and thought.

For now, this new research tool is being used to trace the geographic range of the Neanderthals. We have long known that they lived as far east as Central Asia. Recently, their mtDNA was found in human remains from the Altai Mountains of southern Siberia. Some paleontologists then suggested that all archaic humans across Eurasia would turn out to be Neanderthals of one sort or another.

Now, things no longer look so simple. When Krause et al. (2010) examined a bone fragment from another site in the Altai Mountains, only 100 km farther away, the mtDNA revealed a very different kind of archaic human—genetically almost twice as far from modern humans as the Neanderthals were.

This is puzzling, to say the least. Three kinds of humans—Homo sapiens, Homo neanderthalensis, and now Homo altaiensis (?)—apparently lived within the same geographic area roughly 30,000 to 50,000 years ago. As a rule, three closely related species can co-exist only if they inhabit different ecological niches. Otherwise, one of them will eventually push out the others.

The puzzle may be more apparent than real. Although southern Siberia has yielded evidence of Upper Paleolithic technology up to 40,000 years old, the oldest remains of modern humans date only to a little over 20,000 years ago (Goebel, 1999). We know that some European Neanderthals acquired technological innovations through their initial contacts with modern humans (Hoffecker, 2002, pp. 64, 66, 143, 159, 161-162, 171, 190). Perhaps these innovations spread from the contact zone in Europe to Neanderthals as far away as Siberia.

This still leaves us with a ménage à deux. Or perhaps the recent Altai find was just another kind of Neanderthal. John Hawks (2010) suggests that Siberia may have been a more genetically diverse area within the Neanderthal range. We see a similar situation in modern humans: our gene pool is much more diverse in sub-Saharan Africa than elsewhere, with the result that many mtDNA variants are unique to that continent.

(Off-topic: Keep in mind that most of this genetic diversity is useless. We’re talking about diversity in genes of little or no selective importance. If we look only at genes that have strong real-world effects, there should not be more genetic diversity in one geographic area than in another—unless something in the real world, like selection or intermixture, has been driving that diversity).

But why would Siberian Neanderthals be more genetically diverse than their European cousins? If we look at modern humans, we see that Africans have a high level of genetic diversity because they have stayed longer in one place than all other modern humans. In contrast, Europeans and Asians descend from smaller and more recent founder groups that budded off and left Africa, thereby taking only a fraction of the total genetic variability with them.

Were European Neanderthals an offshoot from an ancestral population in Siberia? I’m not so sure. Given that ancestral Neanderthals ultimately came from Africa, as part of an earlier expansion of archaic humans, why would this expansion have reached Siberia before Europe?

Well, perhaps they reached Europe first and then experienced population crashes specific to that region, the result being a localized reduction in genetic diversity. This leaves unexplained why such crashes would have happened more often in Europe than in Siberia. Indeed, Siberia’s climate spans a wider range of temperatures and is thus likelier to generate the extreme conditions that lead to population crashes.

So John Hawks is possibly right. Probably? No.

One other explanation remains. This is truly another kind of human. Interestingly, there are accounts of a human-like creature that used to roam the Altai Mountains and other highlands of southern Siberia. Called Almas, it supposedly stood five to six and a half feet tall, had reddish-brown hair over its entire body, and possessed a face with a pronounced brow-ridge, flat nose, and weak chin. It may have been part of a larger group of archaic humans that inhabited the mountainous regions of Central Asia, including the yeti of the Himalayas.

Van Deusen (2001) mentions that the Tungus peoples of far eastern Siberia often refer to the past existence of "monkey" people in their region. One folk-tale describes how these "monkeys" once abducted a man:

So the older sister took the shaman's drum. She started to sing and then said, "Brother, when you go hunting in the taiga tomorrow, you're going to meet two people. Check out their breasts, and then marry them."

The next day, he woke up and set out to go hunting. He walked and walked and came to a hill, a mountain. There were big rocks. He looked up, and then went on. Suddenly he saw two people sitting there. He approached and at that time the ties on his skis broke.

He came up to those people and felt their breasts and they were women. And they took him along with them.

At home time went by. A day passed and another, and still he was gone. Many days went by. And then the younger sister said, "Sister, you made this happen. Now you bring him back. Those two monkeys in the mountain came and took him away and now they are keeping him in the mountains, sucking his blood. He's become just skin and bones."

… So the younger sister sang and drummed, flying to her spirits, but she couldn't get there. She tried a second time and still didn't have the strength. The third time she gathered all her strength and flew to those rocks. She took her brother and dragged him out of there. He flew, looking thin as a shirt. They got him back and healed him. And that's how the younger sister brought her brother back from those monkeys.

… So that's it about the monkeys. They lived in the rocks and when they rolled back and forth, they called, "Tsyoo, tsyoo, papandasyoo!!" (Deusen 2001:126-128)

References

Coleman, L. (2010). X-woman discovered. Is she Yeti? Almas? What? Cryptomundo
http://www.cryptomundo.com/cryptozoo-news/x-woman/

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