December 18, 2006

Greg Cochran-John Hawks Clan of the Cave Bear paper out:

Cochran says (on GNXP):

"The major point is that Neanderthals and modern humans were probably interfertile and most likely interbred - and that we would then have picked up most favorable Neanderthal alleles. Which may have something to do with the cultural ' big bang' that happened not long after."

From Paleoanthropology:

Dynamics of Adaptive Introgression from Archaic to Modern Humans

Recent evidence from the genomic variation of living people documents genetic contributions from archaic [e.g., Neanderthal] to later modern humans. This evidence of introgression contrasts with earlier findings from single loci that appeared to exclude archaic human genetic survival. The present evidence indicates that many “archaic” alleles may represent relicts of African archaics, and that some “archaic” variants both inside and outside of Africa have attained relatively high frequencies. Both observations may be surprising under the hypothesis that modern humans originated first in Africa and displaced archaic populations through expansion and drift. Here, we outline how natural selection may have enabled the uptake of introgressive alleles from archaic humans. Even if admixture or gene flow were minimal, the introgression of selected variants would have been highly probable. In contrast to neutral alleles, adaptive alleles may attain high frequencies after minimal genetic introgression. Adaptive introgression can therefore explain why some loci show evidence for some archaic human contribution even as others apparently exclude it. The dynamics of introgression also may explain the distribution of certain deep haplotype branches in Africa. Open questions remain, including the likelihood that archaic alleles retained their adaptive value on the genetic background of modern humans and the scope of functions influenced by adaptive introgression.

John Hawks Department of Anthropology, University of Wisconsin–Madison
Gregory Cochran Department of Anthropology, University of Utah


My published articles are archived at iSteve.com -- Steve Sailer

17 comments:

Anonymous said...

Some Australian aboriginal groups display clear archaic characteristics in their physical appearance - you can see this particularly in photos of Aborigines in older geographical & anthropological works (esp pre 1960s). Apparently the Australian government restricts genetic (and other) study of Aborigines for cultural-Marxist/Politically-Correct reasons, but if this were possible it would likely be a very fruitful line of inquiry re genetic introgression from precursor human populations.

-Simon

Theo_musher said...

It also interesting to me that australian aboriginies have blond children. Their skin is only black if they spend lots of time out in the sun.

They aren't African. I bet they are connected to archaic proto Europeans. I have seen the photos you are talking about, with the big brow ridges. Early European explorers described their features as being "familiar" to Europeans.

Theo_musher said...

I hear there are people in Whales that look very neanderthal but have been unable to find a photo.

Thee are apparemtly descendants of people that have lived in Whales for a very long time, like 100,000 years, I think.

Steve Sailer said...

Aborigines blend in with the white population pretty quickly -- a girl who is 3/4ths white, 1/4th Aborigines will generally strike most people as simply white, maybe with a good tan.

Theo_musher said...

That's interesting because my niece is half white, 1/4 Puerto Rican and only one quarter African American, but she looks not like a white girl with a tan but a light skinned black girl.

Probably she will become culturaly black at some point during highschool or later, even though her Mom is white her Stepfather is White and her little brother is white.

Its an interesting dynamic.

Theo_musher said...

I say this because she slips easily in and out of speaking in ebonics and has the gestures and body language of a black girl. She does these little gestures...its hard to explain in this medium, basically she acts like she is Queen Latiffa or somthing.

I think there probably is more genetic distance between Africans and whites than whites and Australian aboriginals, The African genes seem really dominat too.

tggp said...

Theo Musher: "It also interesting to me that australian aboriginies have blond children. Their skin is only black if they spend lots of time out in the sun."
Really? I know that the early settlers of America from England believed the natives were heavily tanned and dirtied whites, at least according to Thomas Woods' "Politically Incorrect Guide to American History", and that there are a considerable number of blonde and redhead Aborigines, especially deep in the outback. I've seen pictures of blondes, but not redheads. However, I had never heard before that the skin color of Aborigines' is darker than Europeans due to sun. They've lived together for a while now in Australia without (I am guessing) much difference in sun, so wouldn't that result in similar appearance by now?

"They aren't African. I bet they are connected to archaic proto Europeans. I have seen the photos you are talking about, with the big brow ridges. Early European explorers described their features as being "familiar" to Europeans."
They are certainly part of the Out-of-Africa portion of humanity (by an even larger distance than Europeans), but I was under the impression that genetically they are still quite a ways away, even if they aren't close to Africans either.

Theo_musher said...

I am pretty sure that they lose their tans when they put clothes on.

I've read it. I have been into anthropology since I was a kid, and the older books used to be a lot more descriptive about racial differences.

Anonymous said...

"I think there probably is more genetic distance between Africans and whites than whites and Australian aboriginals, The African genes seem really dominat too."

My understanding from popular anthropology, "Before the Dawn" et al, is that Europeans and Australian Aborigines, and indeed all non African populations, are overall more closely related genetically to each other than they are to most African populations, eg the dominant Bantu populations, and the Khoi-San 'bushmen'. Something I find interesting though is that the Knoi San are often regarded as the 'oldest humans', culturally and possibly genetically, but they are much more neotenous (retaining juvenile characteristics to adulthood) than the Aborigines or Europeans, with slimmer build, more gracile skulls, even the epicanthic eye fold otherwose associated with the most neotenous human population, the east-Asians. Europeans' more robust forms can be explained as a cold weather adaptation, but that doesn't apply to the Aborigines, whose ancestor populations seem to have come straight east from Africa along the south coast of Eurasia.

Could it be that the Khoi San represent the oldest 'pure' strain of modern humans, while the Australian Aborigines, and possibly Europeans, have features resulting from introgression by Neanderthal (European) and Homo Erectus (Aborigines)? Alternatively, are Aborigines an unchanged relic of our earliest days, while the Khoi San went on evolving for increased gracilism (partly via neotony) to their present form?

-Simon

Steve Sailer said...

Simon:

Both your speculations seem plausible. Of course, that shows that we all have a lot left to learn.

Theo_musher said...

Actually there is mtDNA evidence that the San Bushmen are the oldest, and are direct descendants of the ancestors of all mankind.

Vol-in-Law said...

Theo, re the mtDNA, as I understand it, since mtDNA variations we study are normally neutral rather than favourable they don't necessarily spread through a population the way a favoured gene will. So a relative lack of mtDNA variation among aborigines or Europeans is not the strong evidence against interbreeding with precursor populations that is sometimes claimed, because over time incursive mtDNA lines (eg from Neanderthals) will likely die out unless they offer an adaptive advantage.

Theo_musher said...

Well that's interesting. I wondered about that. I know there is the out of africa theory and the multiple origins theory, and I thoughtb the out of africa theory had the proof through the mtdna, but I have always been fascinated by the possible neanderthal contribution.

Thanks for the info.

Simon said...

Yup - from all the evidence, all modern mtDNA lines support "out of Africa", but all they show is the direct female line of descent. They definitely don't mean that modern human populations have no (eg) Neanderthal or recent Homo Erectus ancestors at all, they only show we have no direct-female-line Neanderthal or Homo Erectus ancestors. Y chromosome data shows the same for direct-male-line.

The only way I can think of that this data would indicate zero introgression would be if it could somehow be shown that eg Neanderthal mtDNA or homo erectus Y chromosomes etc conferred a selective advantage, if that were the case then their absence in modern humans would indicate no interbreeding as interbreeding + selective pressure would have spread them through the population.

Theo_musher said...

Well that makes sense. I have a hard time thinking most Homo Sapiens Sapiens would go for a neanderthal chick!

Maybe the Neanderthals dominated the Homo Sapiens and stole the women, and sexual selection weeded out all the hairy beetle browed females, so then the neanderthals went extinct that way.

rodney_judd@yahoo.com. au said...

Australian aborigines are more similar to white people than African Negroes. I have even heard it said that they may have moved east to places like Tierra del Fuago and interbred with the mongoloid ancestors of the American red indians. It certainly seems plausible that the polynesians of the south pacific are a hybrid racial combination of australian aborigines and Mongoloids.My own theory is that the modern human did not emanate from africa but rather australia. At Lake Mungo remains of aborigines lie side by side with the bones of Neanderthals. The assertion that aborigines are only dark skinned because of suntan is quite absurd as any argument based on skin colour. In fact Hitler's concept of the blond aryan is ridiculous because Aryan refers rather to language rather than race. Aryan equates with Indo Europeans and skin colour varies dramatically from Northern Europe through the Mediterranean to India. The Dravidian peoples of South India often strongly resemble the Australian aborigine.

Robert Dole said...

“Will some of these Neanderthal fragments be found to be important in cognition, language ability, and other higher brain functions? To find out, it will be necessary to understand the human epigenome and transcriptome in detail, so that we can determine the true impact of both structural and regulatory genes on the development and function of the brain.”

http://www.pdf-archive.com/2011/12/05/autism-outline/autism-outline.pdf