Out of Africa Myth Debunked

[TylerDurden]

I've always been annoyed with the whole Creationist-like Out of Africa myth where modern humans supposedly magically appeared in Africa between 50,000 to 200,000 years ago and spread all over the globe supposedly wiping out the Neanderthals. Here is evidence that modern humans interbred with the Neanderthals(and I'm sure that other apemen species all over the globe  interbred with other hominids including Cro-Magnon as well):-

http://www.telegraph.co.uk/science/7685610/Humans-share-Neanderthal-genes-from-interbreeding-50000-years-ago.html

In other words, the Neanderthals, Homo Erectus, Cro Magnon etc. were not separate species but all one happy family, capable of interbreeding with each other.

[SkinnyDevil]

Interesting. I'd always heard they did NOT find any DNA linking homo sapiens sapiens to homo neanderthalensis. Go figure. It'll be inteesrtying to see how this shakes out.

As an aside, Cro-Magnon is not a scientific term, and refers to a homo sapiens find in southern France. The finds are from roughly 35,000 years ago (upper paleolithic).

[TylerDurden]

That's incorrect as it refers to a specific ethnic group. "Cro-magnon"  may not refer to absolutely ALL modern humans at the time, but as long as it refers to one of the  primary European palaeo populations, it's still valid as a term. Besides, there are no other groups which practised palaeo-style cave-paintings, making the Cro-Magnon very unique/interesting in that regard.

[SkinnyDevil]

Perhaps I was unclear. I was responding to your statement: "In other words, the Neanderthals, Homo Erectus, Cro Magnon etc. were not separate species but all one happy family, capable of interbreeding with each other."

I was pointing out that Cro-Magnon belong to the line Homo Sapiens Sapiens (modern humans), as opposed to Neanderthals, Homo Erectus, Heidelbergs, Homo rhodesiensis, etc., who do not.

Additionally, Cro-Magnons are not some sub-species of sapiens, but simply the name given to early humans. The name came from the first site in France, but anatomically/technologically similar examples of early humans are found from northeast Africa and spreading out over time to west Africa, the Middle East, southeast Asia, and all over Europe.

[TylerDurden]

Well, it's pretty clear now, given the level of interbreeding between homo sapiens sapiens and Neanderthals that modern humans cannot any more be considered entirely separate lines from  the other ancient hominids. We modern humans clearly all have elements from all the various types as a result of hundreds of millenia of interbreeding with each other.

As for the Cro-Magnon term, I find that it's more commonly associated with western Europe, southern France in particular. I suppose terms like "early modern human" etc. are preferred nowadays, but are so vague and boring I don't like using them.

[PaleoPhil]

An alternative interpretation of the data has been proposed:

"When scientists discovered a few years ago that modern humans shared swaths of DNA with long-extinct Neanderthals, their best explanation was that at some point the two species must have interbred.

Now a study by scientists at the University of Cambridge has questioned this conclusion, hypothesising instead that the DNA overlap is a remnant of a common ancestor of both Neanderthals and modern humans."

http://www.guardian.co.uk/science/2012/aug/14/study-doubt-human-neanderthal-interbreeding?newsfeed=true

I'm not trying to imply by sharing this that I'm taking a position. I have no dog in the hunt and I actually thought it pretty neat that I might have some Neanderthal genes.

[TylerDurden]

I just don't buy the above nonsense. I mean, current ethnic groups among modern humans can interbreed with each other, so it is extremely unlikely that more ancient hominids couldn't interbreed with each other. There is evidence of intermixture of archaic hominids with HS re current African populations and Denisovan hominid intermixture with certain peoples in East Asia which is also not referred to above, suggesting that it's just a last-ditch attempt to protect the out of africa theory.

[PaleoPhil]

I'd be mildly pleased if you're right (so I guess I do have a small dog in the hunt--in favor of hypotheses like Paabo's that involve significant mixing with Neanderthals).

The article also included a critical response from the opposing camp:

"Prof Svante Pääbo, at the Max Planck Institute for Evolutionary Anthropology in Leipzig, who led the sequencing of the Neanderthal genome in 2010 and has championed the idea that modern humans interbred with Neanderthals, said he was surprised that Manica's work had been published, since his original paper had admitted a role for substructuring in Africa in the sharing of DNA between humans and Neanderthals. "But we regard this as a less parsimonious explanation" ....

And Paabo will be publishing another that he says will further support his hypothesis. I'm looking forward to that.

By the way, it sounds like what you're referring to is the "strong form" of the "Out of Africa theory" that assumes a strong infertility barrier. There's also a weak form(s) that accepts some admixture of Neanderthals, Denisovans, etc. (see http://en.wikipedia.org/wiki/Recent_African_origin_of_modern_humans and below). Indeed, Peter Frost, who is no libtard, actually took Paabo's interpretation of the Neanderthal DNA findings of around 1-4% outside Africa (and Frost expects somewhat more with additional data) to be supportive of the weak form of the OOA theory and he even wrote: "The winning model is a weak version of Out of Africa." (http://evoandproud.blogspot.com/search?q=%22out+of+africa%22+neanderthal)

Here is more on the intermediate hypotheses:

While the multiregional model of human origins posits a number of independent single locus selective sweeps, and the ‘‘out of Africa’’ model posits a sweep of a new species, we study the intermediate case of a phenotypic sweep. Numerical simulations of this process replicate many of the seemingly contradictory features of the genetic data, and suggest that as much as 80% of nuclear loci have assimilated genetic material from non-African archaic humans. ....

Others have proposed models intermediate between the strict RAO and MRE models (Smith, 1985; Relethford, 2001; Templeton, 2002). Relethford called his version ‘‘mostly out of Africa’’ because in it there is actual movement of populations from Africa. These newly arrived Africans mostly replace the local archaics, but there is some degree of admixture. On the other hand, in our model, there is no long distance movement of populations at all; change is driven entirely by local gene exchange among demes and natural selection. This model has the advantage of parsimony and simplicity, and it will be important to disentangle the effects of selection and long range migration from the archaeological and fossil records.

(Genomics refutes an exclusively African origin of humans, wiki.majorityrights.com/_media/race/eswaran.pdf)

[cherimoya_kid]

I just don't buy the above nonsense. I mean, current ethnic groups among modern humans can interbreed with each other, so it is extremely unlikely that more ancient hominids couldn't interbreed with each other. There is evidence of intermixture of archaic hominids with HS re current African populations and Denisovan hominid intermixture with certain peoples in East Asia which is also not referred to above, suggesting that it's just a last-ditch attempt to protect the out of africa theory.

IIRC, the Neanderthal DNA was mainly found only in Europeans, right?  Not sub-Saharan Africans?  If that's true, then obviously there had to be some intermixing.

[TylerDurden]

IIRC, the Neanderthal DNA was mainly found only in Europeans, right?  Not sub-Saharan Africans?  If that's true, then obviously there had to be some intermixing.

Neanderthal DNA was found in all non-africans, actually.

[PaleoPhil]

IIRC, the Neanderthal DNA was mainly found only in Europeans, right?  Not sub-Saharan Africans?  If that's true, then obviously there had to be some intermixing.

That's an excellent question. I took Andrea Manica's explanation here--"The idea is that our African ancestors would not have been a homogeneous, well-mixed population but made of several populations in Africa with some level of differentiation, in the way right now you can tell a northern and southern European from their looks."--to indicate that she believes there was likely at least one ancestral African population that had the "Neanderthal" genes. It would help her case if she found evidence of such a population. Until then, the evidence is lacking, though absence of evidence isn't evidence of absence, of course.

[TylerDurden]

Well, so far it's been shown that no africans possess Neanderthal DNA.

Incidentally, if you look at various online reconstructions of the Neanderthals you will see often a very Jewish-like(well, semitic) resemblance, thus implying that they might have inherited a much larger portion of such DNA. There has been some speculation re this, from Stan Gooch onwards(himself Jewish) who pointed this out, and it is well-known that there was a Neanderthal population in the Middle-East.

What I find fascinating about the Neanderthals is that they had red hair and white skin. OA scientists have been trying to claim that white skin/light hair/light-coloured eyes only appeared very recently, which increasingly looks dodgy when one realises that previous hominids also had such traits.

[Wattlebird]

Regarding Neanderthals, the fictional novel, Clan of the Cave Bear, is an interesting read - not in terms of an accurate portrayal of how Neanderthals lived (however that may have been), but rather in terms of how the author believed they lived, especially in terms of culture, interbreeding, diet, hunting, shamanism and herbal lore.

[PaleoPhil]

Well, so far it's been shown that no africans possess Neanderthal DNA.

Almost--no one has so far shown "Neanderthal" DNA in any living or past Africans, but absence of evidence is not evidence of absence. People in the West also used to claim for centuries that there were no black swans until the first ones were witnessed in Australia. Nonetheless, there's enough other evidence that I doubt they'll find significant amounts of "Neanderthal" DNA in Africa outside of the Northeast corner and John Hawks wrote a convincing refutation of Eriksson and Manica's African-Neanderthals hypothesis here:
http://johnhawks.net/weblog/reviews/neandertals/neandertal_dna/neandertal-ancestry-iced-2012.html

Without evidence of Neanderthal DNA in either living or past African peoples, I find Eriksson and Manica's alternative hypothesis difficult to believe.

What I find fascinating about the Neanderthals is that they had red hair and white skin.

There is an alternate interpretation of the data on that, too, and Hawks has a more nuanced view on it than on the African-Neanderthals hypothesis:

"Now new DNA analysis suggests that two of the most closely studied Neandertals—a pair of females from Croatia—were actually brown-eyed girls, with brunette tresses and tawny skin to match. ...

The study has provoked deep skepticism among several outside researchers, however, who criticize numerous aspects of its methodology. The results also run contrary to other genetic evidence and to a long-held hypothesis that Neandertals, who lived mostly in northern latitudes, must've had light skin to get enough vitamin D. [Though the sexual selection hypothesis for the origin of fair skin and hair contradicts that view.]

But even scientists who have doubts about the new research say it still provides food for thought. "Neandertals occupied a wide geographical range," says John Hawks of the University of Wisconsin, Madison, who was not involved in the study and who is also studying the physical traits of ancient humans, so "it's likely that they were variable in pigmentation. ... We are really at the first step. ....

Although Hünemeier and her critics differ on the methods her team used, they agree that the stereotypical view of Neandertals is too narrow. Lalueza-Fox says Neandertals probably had brown eyes and a variety of hair colors, and Hawks thinks Neandertals living in places such as Israel may have had darker skin than their European counterparts."

(Were Some Neandertals Brown-Eyed Girls? http://news.sciencemag.org/sciencenow/2012/03/were-some-neandertals-brown-eyed.html)

It will be interesting to see what future research produces.