September 16, 2011

Chris Stringer video on BBC on Iwo Eleru skulls

Skull points to a more complex human evolution in Africa
"[The skull] has got a much more primitive appearance, even though it is only 13,000 years old," said Chris Stringer, from London's Natural History Museum, who was part of the team of researchers.

"This suggests that human evolution in Africa was more complex... the transition to modern humans was not a straight transition and then a cut off."

Prof Stringer thinks that ancient humans did not die away once they had given rise to modern humans.

They may have continued to live alongside their descendants in Africa, perhaps exchanging genes with them, until more recently than had been thought.

The researchers say their findings also underscore a real lack of knowledge of human evolution in the region.

My previous blog post on the published article here.

A thing that has troubled me in reading a few recent palaeoanthropological comparative analyses is the fact that the Omo I, the "modern" of the ~195ka Omo skulls, as well as Herto do not seem to be included. Is this a case of anthropologists guarding their data, a problem that seems to have particularly plagued paleoanthropology? This is not an idle question: how would these ~200ka and ~150ka finds, widely touted as our ancestors fare when placed in the same analysis as the skulls of Harvati et al. (2011) or Mounier et al. (2011)?

Omo II, the most "archaic" of the Omo skulls was included in Mounier et al. (2011) and seemed to be related to Skhul 5 and Jebel Irhoud 1, which would probably place it in the intermediate (archaic/modern) category. How about Omo I?

I don't know, and I'd like to see some hard numbers on exactly how modern it is compared to extant humanity. It has often been repeated, for example, that the Skhul/Qafzeh hominins from the Levant represent an early Out-of-Africa movement, but they appear, at least in the latest Harvati et al. analysis to be well within the range of modern human variation, and certainly more so than all the included African samples of similar, or even younger age.

This seems counterintuitive: if, as the current orthodox theory holds, modern humans -in the strict sense of being like living people- originated in Africa ~200ka and spread to the rest of the world ~60ka, why are the Mt. Carmel hominins apparently more modern than their African counterparts of similar age? Remember, that it has been hypothesized that Skhul/Qafzeh represent a population that may be mixing with Eurasian Neandertals, which would make them less like modern people, not more.

Moreover, if modern humans did originate in Africa ~200ka, then why did they admix with archaic Africans only ~35ka (per Hammer et al. 2011) and had not replaced archaic Africans even ~13ka? Apparently, the current narrative proposes, they replaced all archaic hominins in Eurasia in practically a few thousands of years, but they could not achieve the same in nearly 0.2My in Africa? Or, they admixed with archaic Eurasians before they admixed with their next-door neighbors, the archaic Africans? Something does not seem right.

How would Omo I and Herto fare if they had been included? Ancestral H. s. sapiens, where art thou? Let's find out.


German Dziebel said...

"Moreover, if modern humans did originate in Africa ~200ka, then why did they admix with archaic Africans only ~35ka (per Hammer et al. 2011) and had not replaced archaic Africans even ~13ka?"

IMO, the answer is simple: modern humans who are our ancestors entered Africa around 40,000 years ago and in some areas admixed with pre-existing hominids, who showed their own set of archaic/modern features. People assumed that the so-called AMH in Africa must be our ancestors but how do we know this for sure? There are no DNA samples. What if these African hominids, who were behaviorally Mousterian, were completely replaced in Africa by 10K years just lie Neandertals were replaced in Europe by 40,000 years? There was no exodus out of Africa, but only a migration into Africa. Another useful skull is South African Hofmeyr at 36,000 that clustered with UP Eurasians. F. E. Grine, FE; R. M. Bailey, K. Harvati, R. P. Nathan, A. G. Morris, G. M. Henderson, I. Ribot, A. W. G. Pike (12 January 2007). "Late Pleistocene Human Skull from Hofmeyr, South Africa, and Modern Human Origins". Science 315 (5809): 226–229.

Andrew Oh-Willeke said...

"Moreover, if modern humans did originate in Africa ~200ka, then why did they admix with archaic Africans only ~35ka (per Hammer et al. 2011) and had not replaced archaic Africans even ~13ka?"

An admixture date starting ca. 100kya to 70 kya, roughly when Khoisan and Pygmies would have diverged to the point that they became distinct populations, and replacement of archaic Africans in a similar time frame to that observed in Europe would certainly seem more plausible to me. Since this is pretty much one study's data point in dates (by a largely unproven method) and uses only a single methodology, it is surely the least robust date of the lot.