The ancestors with no descendants

Venus of Mal’ta, a figurine from a site in eastern Siberia (source). She comes from a population that was related to modern Europeans and Amerindians but not to modern native Siberians. The Mal’ta Siberians died out at the height of the last ice age and were replaced by people spreading north from East Asia and west from Beringia.

On the eve of the last ice age, Siberia was home to a people who were related to modern Europeans and Amerindians but not to modern native Siberians. So concludes an analysis of DNA from the remains of a boy who lived 24,000 years ago at Mal’ta near Lake Baikal, Siberia.

They found that a portion of the boy's genome is shared only by today's Native Americans and no other groups, showing a close relationship. Yet the child's Y chromosome belongs to a genetic group called Y haplogroup R, and its mitochondrial DNA to a haplogroup U. Today, those haplogroups are found almost exclusively in people living in Europe and regions of Asia west of the Altai Mountains, which are near the borders of Russia, China, and Mongolia.

One expected relationship was missing from the picture: The boy's genome showed no connection to modern East Asians. DNA studies of living people strongly suggest that East Asians—perhaps Siberians, Chinese, or Japanese—make up the major part of Native American ancestors (Balter, 2013).

These findings are consistent with earlier ones. Strong dental and cranial affinities exist between remains from the same site and those of Upper Paleolithic Europeans (Alexeyev and Gokhman, 1994). Also, when we compare the Clovis sites of early Amerindians (13,000 BP) with early European and Siberian sites (20,000-15,000 BP), we find many features in common: characteristic lithic technology, grave goods with red ocher, and sites with small shallow basins (Goebel, 1999; Haynes, 1980; Haynes, 1982).

What do these findings tell us? I would propose the following:

1. When the last ice age began some 25,000 years ago, a single population of nomadic hunters occupied the steppe-tundra that stretched from southwestern France to Beringia.

2. Ancestral East Asians had already split away from this proto-Eurasian population. They had probably adapted to life farther south in the more temperate environments of what is now north China. The Ainu may be an evolutionarily conservative branch of these East Asians.

3. At the height of the last ice age some 20,000 to 17,000 years ago, Siberia became virtually devoid of human life (Graf, 2009a; Graf, 2009b). Proto-Eurasians survived in refugia in parts of Europe to the west and in coastal regions of northeast Asia, Beringia and northwest North America to the east. Kennewick Man (c. 9,000-10,000 BP) may have been an example of this refuge population.

4. Siberia was then repeopled by two streams of settlement. One was composed of ‘Kennewickians’ spreading westward and inland from coastal refugia. The other stream was composed of early East Asians spreading northward.

5. This new mixed population of eastern Siberia and Beringia would later spread eastward into the interior of post-glacial North America around 13,000 years ago. These people were the early Amerindians of the Clovis culture.

It would be interesting to know what the reconstructed Mal’ta genome tells us about the skin, hair, and eye color of the proto-Eurasians. Were they pale-skinned with a diverse palette of hair and eye colors, like modern Europeans? Or were they brown-skinned with black hair and brown eyes, like modern Amerindians?  Probably the second possibility, given that the European color scheme seems to be a later evolutionary development—11,000 to 19,000 years ago for white skin and probably the same time frame for diversification of hair and eye color (Beleza et al., 2013). The Mal’ta people might have gone on to develop the same characteristics during this time frame, but they all died out at the height of the last ice age. 

In short, the Mal’ta people probably looked very much like native Indians with a more European skull shape, perhaps like the Ainu of northern Japan or the Kennewick humans of North America. 

References

Alexeyev, V.P., and I.I. Gokhman. (1994). Skeletal remains of infants from a burial on the Mal'ta Upper Paleolithic site, Homo, 45, 119‑126. 

Balter, M. (2013). Ancient DNA links Native Americans with Europe, Science, 342, 409-410.

http://www.sciencemag.org/content/342/6157/409.full

Beleza, S., A. Múrias dos Santos, B. McEvoy, I. Alves, C. Martinho, E. Cameron, M.D. Shriver, E.J. Parra, and J. Rocha. (2013). The timing of pigmentation lightening in Europeans, Molecular Biology and Evolution, 30, 24-35.

http://www.utm.utoronto.ca/~parraest/profile/PDF%20files/Beleza-2012(Mol.Biol.Evol.).pdf 

Goebel, T. (1999). Pleistocene human colonization of Siberia and peopling of the Americas: An ecological approach, Evolutionary Anthropology, 8, 208‑227.

http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1520-6505(1999)8:6%3C208::AID-EVAN2%3E3.0.CO;2-M/abstract

Graf, K.E. (2009a). “The Good, the Bad, and the Ugly”: evaluating the radiocarbon chronology of the middle and late Upper Paleolithic in the Enisei River valley, south-central Siberia. Journal of Archaeological Science, 36, 694–707.

http://www.centerfirstamericans.com/cfsa-publications/Graf-JAS2009-36-694.pdf

Graf, K.E. (2009b). Modern human colonization of the Siberian Mammoth Steppe: A view from South-Central Siberia. In M. Camps, P. Chauhan (eds.), Sourcebook of Paleolithic transitions (pp. 484-496), Springer Science & Business Media.

Haynes, C.V. (1982). Were Clovis progenitors in Beringia? In D.M. Hopkins (ed). Paleoecology of Beringia, (pp. 383‑398), New York: Academic Press. 

Haynes, C.V. (1980). The Clovis culture, Canadian Journal of Anthropology, 1, 115‑121.

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/

Goebel, T. (1999). Pleistocene human colonization of Siberia and peopling of the Americas: An ecological approach. Evolutionary Anthropology, 8, 208-227.

Hawks, J. (2010). Hobbit version 2.0: the undiscovered hominin. John Hawks Weblog, March 24, 2010.
http://johnhawks.net/weblog/reviews/neandertals/neandertal_dna/denisova-krause-2010.html

Hoffecker, J.F. (2002). Desolate Landscapes. Ice-Age Settlement in Eastern Europe. New Brunswick: Rutgers University Press.

Krause, J., Q. Fu, J.M. Good, B. Viola, M.V. Shunkov, A.P. Derevianko, & S. Pääbo. (2010). The complete mitochondrial DNA genome of an unknown hominin from southern Siberia, Nature, early online.

Van Deusen, K.V. (2001). The Flying Tiger. Women Shamans and Storytellers of the Amur. Montreal: McGill-Queen's University Press.

Watson, E., P. Forster, M. Richards, & H-J Bandelt. (1997). Mitochondrial footprints of human expansions in Africa, American Journal of Human Genetics, 61, 691-704.