Thursday, 1 April 2010

Homo altaiensis?


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.

8 comments:

Ben10 said...

It's hard to believe no skeletons of Almas or yeti, no frozen skins, teeth, feces, nothing, has never been found, if they were real.

But back on something you said in an earlyer thread, that some modern humans' mitochondrial dna is closer to the neanderthal's mitochondrial dna than to other others moderns human's dna. Did I correctly understand? and if yes, can you briefly elaborate on it to explain how that can be?

Peter Frost said...

Ben10,

If you look at individual DNA sequences, some modern humans will be closer to some Neanderthals than they are to other modern humans. We see the same genetic overlap when we compare human populations. Some Danes are closer to some Congolese than they are to other Danes.

In both cases, the overlap disappears when we look at more than one DNA sequence at the same time. The more sequences we compare simultaneously, the less overlap there will be.

Why does this overlap exist even when we compare individual chunks of DNA? The reason is that most genes have little or no selective value. So the selection pressure on them is pretty much the same in any population, be it Congolese, Danish, or Neanderthal.

Of course, once two populations have become reproductively isolated, i.e., when they have become different species, their DNA will drift apart even at genes of low selective value (because the ‘noise’ introduced by random mutations will not be the same). But this gradual divergence takes a very long time. For this reason, it is difficult to tell related species apart if they have arisen only over the last 40,000 years. Even Neanderthals and modern humans still have some overlap, despite being apart for a much longer period.

From the literature:

“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, 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.

“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, 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.

Anonymous said...

Ben10 :
It's hard to believe no skeletons of Almas or yeti, no frozen skins, teeth, feces, nothing, has never been found, if they were real.


Indeed, but why these folk stories in several very different regions of the world about the same kind of archaic monkey-like creatures? (actually feces and footprints have been supposedly found, in north america at least, but as for their authenticity, I don't know much of what have been done to verify it).

And we had to wait for 2010 to know about this homo altaiensis.
How many surprises to discover?

Tod said...

Wouldn't food be very hard to come by in areas such as the highlands of southern Siberia.

The Neanderthals in Europe seemed to have routinely been eating their way through a lot of meat. That suggests that in the Neanderthal era Europe was swarming with game, and game which was naive and easy prey for them. Maybe Almas had throwing weapons and were quick on their feet but there would have been long treks for food in a bleak landscape where the prey had to be hunted down. Homo altaiensis could't just lurk around the game trails and wait for dinner to arrive like European Neanderthals

Tod said...

Wouldn't food be very hard to come by in areas such as the highlands of southern Siberia in the era of human settlement of that area is what I meant. 50,000 years ago there could have been lots to eat there for Homo altaiensis.

Anonymous said...

Suggested 2010 Genetics Concepts Update

Genetic Diversity In Humans And In Cells

A cell, each and every cell, hosts thousands of not-celled organisms, both RNA and DNA organisms.

Exploring genetic diversity
Readjust concepts and comprehension

"03.2010 Updated Life Manifest"
http://www.the-scientist.com/community/posts/list/54.page#5065

Organisms that we host:

A. 3rd stratum cellular organisms

Our bacterial symbionts: There are ten times more bacteria colonizing a human than the number of human cells in the body (10^14 versus 10^13, respectively). Circa 900 taxa. The structures of their communities vary tremendously. The gut might be considered New York City, whereas the skin is perhaps more like Memphis


B. 2nd stratum cellular organisms, DNA multigenes, genomes, cooperative operational work-patterns for the RNA genes, evolved and maintained by the RNAs for carrying on life processes.

The RNAs work pattern genes, the cooperative-linked DNA genome-members, are distributed unevenly across the chromosomes. Each chromosome contains various gene-rich and gene-poor regions, which seem to be correlated with chromosome bands and GC-content. The significance of these nonrandom patterns of gene density is not well understood.


C. 1st stratum not-celled primal Earth ORGANISMS, the individual RNA genes and the above DNA genome members genes.

There are estimated to be between 20,000 and 25,000 human protein-coding DNA genes, organisms, linked members of the DNA genome.

In addition to protein coding DNA genes, the human genome contains thousands of RNA genes, including tRNA, ribosomal RNA, microRNA, and other non-coding RNA genes.

Surprisingly, the number of human DNA genes seems to be less than a factor of two greater than that of many much simpler organisms, such as the roundworm and the fruit fly. However, RNAs in human cells make extensive use of alternative splicing to produce several different proteins from a single DNA gene, and the human proteome is thought to be much larger than those of the aforementioned organisms. Besides, most human DNA genes have multiple exons, and human introns are frequently much longer than the flanking exons.


Dov Henis
(Comments From The 22nd Century)
http://www.the-scientist.com/community/user/profile/1655.page
Cosmic Evolution Simplified
http://www.the-scientist.com/community/posts/list/240/122.page#4427
Seed of Human-Chimp Genomes Diversity
http://pulse.yahoo.com/_2SF3CJJM5OU6T27OC4MFQSDYEU/blog/articles/53079
Evolution, Natural Selection, Derive From Cosmic Expansion
http://darwiniana.com/2010/09/05/the-question-reductionists-fear/

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Anonymous said...

The admixture with neanderthals/yetis has long been hypothesized to explain quite a few sociopolitical phenomena:

http://najmita.150m.com/szukalski/macimowa/yetisyny_ang.htm

The Yetinsyn should be considered more or less alongside with NAM in any HBD-informed analysis of sociopolitical issues from now on. Of course, not as if they're exactly the same group, as it would be just another instance of HBD-denial.