Movement into and out of Africa has probably been going on periodically since H. habilis/H. erectus first left Africa. It certainly seems to me that the nearly two million year old phenotype observed in Georgia lies at the base of a phenotype change in Africa. And this paper points out that later H. erectus looked much the same at all geographic points of its range. That suggests a lot of gene flow.

I provided evidence supporting this scenario in one of my essays at remotecentral, “Species or not”, dealing with H. heidelbergensis:

http://remotecentral.blogspot.com/2008/02/human-evolution-on-trial-species-or-not.html

You may like to read it and comment. Perhaps we can improve the ideas and presentation to make it easier for others to understand.

Unlike the out of Africa theory, the out of America theory doesn’t provide a finished picture of human prehistory (science always tends to quickly provide a final word only to retrieve it a couple of decades later) but identifies where opportunities for cross-disciplinary integration and future research can be found.

But this is exactly what the out of America theory, in my formulation, hinges on: early evolution in Asia from Homo erectus, speciation in America, back migration of modern humans into the Old World (exactly like woolly mammoths), all the way into Africa. Morphological continuity traits between Asian Homo erectus, on the one hand, and Asian and Amerindian populations, on the other, are well-documented.

First: “Bivariate and principal component analyses indicate that geographical variation does not characterize the ZKD, African and other Asian specimens”.

So, unlike virtually every other species, H. erectus did not form regional varieties. Absolutely unbelievable. Conventional wisdom has it that modern humans have formed geographical varieties in just 100,000 years, at most. Yet H. erectus failed to do so over virtually a million years . This sugests an unbelievably rapid pattern of gene flow, especially surprising in a species supposedly lacking many of our modern methods of rapid dispersal.

Second: “ZKD V shows important differences, including broader frontal and occipital lobes, some indication of fuller parietal lobes, and relatively large brain size that reflect significant trends documented in later hominin brain evolution”.

Ah. Here we have indications of regional change. But in Asia, rather than in Africa where conventional wisdom has it that modern humans originated.

How could elements of modernity arise in Asia long before any modern humans came out of Africa? Perhaps the OoA people actually originated from an earlier movement INTO Africa from Asia. It’s possible. But it doesn’t fit the beliefs of those who claim modern humans arose in Africa from a group of H. erectus who had never left that continent.

the statistics in the research can be interpreted as a generalisation trend toward modern human in the zdk. however i am well aware of the chinese notion to interprete the finds in the multiregional model. to that i have the following remark (wich i made in another context before) that among erectus the population dispersal appears to be ‘spearheaded’(i think they went pretty slow) by relatively isolated groups as witnessed in characteristical traits of remains for the diverse sites. from a slighter wider then anthropocentric dimension (ie. considering the development of species over 10 million years) this suggests we will find remains to the extremes of variation, and perhaps with relative ease, (basically noone to clean the caves in between habitation layers), the multiregional prongs however would express closer to the centre of the hominid habitat. homo georgicus suggest se-asia was more of a gene pool then most other areas outside africa. so we need new ‘missing links’;), from eg pakistan, iran or egypt to get a better grasp on homo erectus versatility.it is also possible that the general trends for development of a brain like ours were present in what we call erectus nowadays, and that the population in africa and asia for that reason developed similar in relative isolation. in either case the point can be made that erectus must be considered the direct ancestral lineage for sapiens in a (probably) continuous genetical exchange. that btw is also what the morphology of the plenty chinese erecti suggests.