The single Out of Africa hypothesis was clearly grossly oversimplified as I have posted about before. The narrative I still find most likely is that there were multiple Out of Africa events for AMH by two main routes starting from about 130,000 years ago. One to the Northern end of the Arabian peninsula from what is now Egypt and one from the Horn of Africa to the Southern part of the Arabian peninsula. Settlements did establish themselves around the now submerged portion of Arabia and the Persian Gulf. There was at least one wave, and probably many waves, of modern humans which, prior to the Toba explosion 74,000 years ago, found its way to the western parts of SE Asia (now Burma, Malaysia and perhaps as far as Laos) but id not reach Australia. Much of that wave perished with Toba, but some few survived and mixed with those who came later. Now a new paper shows that there must also have been an early (c. 80,000+ years ago), expansion along a route from the fertile crescent into Southern China, probably displacing the homo erectus cousins of the Neanderthals who were extant there. (This could even be the “unknown” hominids concurrent with Neanderthals and Denisovans). Possibly they were constrained to move East by the Neanderthals who then occupied central Asia and Europe.
The Great Expansion which started some 60,000 -70,000 years ago eastwards from Africarabia, after the Toba explosion, was then the one which reached Australia about 60,000 years ago. It was this population which also expanded into central Asia in two or more great streams; one Westwards into Europe and one Northwards and Eastwards across the steppes of Russia and across Northern China. The mixed with the pre-modern hominids they came across. I speculate that it was in fact their superior social skills (group size, specialisation of skills, trade behaviour and language) which led to their eventual dominance and the gradual decline and absorption of all the homo species they came across.
Wu Liu et al, The earliest unequivocally modern humans in southern China, Nature (2015), Published online14 October 2015, doi:10.1038/nature15696
Abstract: The hominin record from southern Asia for the early Late Pleistocene epoch is scarce. Well-dated and well-preserved fossils older than ~45,000 years that can be unequivocally attributed to Homo sapiens are lacking1, 2, 3, 4. Here we present evidence from the newly excavated Fuyan Cave in Daoxian (southern China). This site has provided 47 human teeth dated to more than 80,000 years old, and with an inferred maximum age of 120,000 years. The morphological and metric assessment of this sample supports its unequivocal assignment to H. sapiens. The Daoxian sample is more derived than any other anatomically modern humans, resembling middle-to-late Late Pleistocene specimens and even contemporary humans. Our study shows that fully modern morphologies were present in southern China 30,000–70,000 years earlier than in the Levant and Europe5, 6, 7. Our data fill a chronological and geographical gap that is relevant for understanding when H. sapiens first appeared in southern Asia. The Daoxian teeth also support the hypothesis that during the same period, southern China was inhabited by more derived populations than central and northern China. This evidence is important for the study of dispersal routes of modern humans. Finally, our results are relevant to exploring the reasons for the relatively late entry of H. sapiens into Europe. Some studies have investigated how the competition with H. sapiens may have caused Neanderthals’ extinction (see ref. 8 and references therein). Notably, although fully modern humans were already present in southern China at least as early as ~80,000 years ago, there is no evidence that they entered Europe before ~45,000 years ago. This could indicate that H. neanderthalensis was indeed an additional ecological barrier for modern humans, who could only enter Europe when the demise of Neanderthals had already started.
The teeth, excavated from Fuyan Cave in Daoxian, southern China, represent the earliest unambiguous evidence for Homo sapiensoutside of Africa.
“They are indeed the earliest Homo sapiens with fully modern morphologies outside of Africa,” lead author Wu Liu of the Chinese Academy of Sciences told Discovery News. “At the Levant (much of the eastern Mediterranean), we also have human remains from the sites of Qafzeh and Skhul (in Israel) with similar ages, but these fossils have been described as retaining some primitive features and, thus, are not fully modern.” …….
…….. Some researchers have even proposed an “Out of Asia” instead of “Out of Africa” migration path for the first Homo sapiens.
While the new findings do not resolve that question, they do reveal that our species was in southern China up to 70,000 years before it was in the eastern Mediterranean and Europe. The newly unearthed remains also offer evidence that China during the Pleistocene Era was likely inhabited by multiple groups of humans: our species and another more primitive lineage(s). Prior fossil discoveries show that the primitive Denisovans, for example, were in northern Asia.
Further complicating the mix is that Neanderthals were also living outside of Africa at the same time. The researchers suspect that the Neanderthals’ presence might have even deterred our species’ migration into Europe, since it took Homo sapiens so long to get there. Intriguingly, Neanderthals went extinct, or perhaps were absorbed into the Homo sapiens population, shortly after our species landed on what was Neanderthal turf. …….
The southern China cave where the teeth were found unfortunately provides no clues on what the culture of Homo sapiens was like there 80,000–120,000 years ago. No prehistoric tools or other telltale artifacts have been found so far at the site……..
The single Out of Africa event for modern humans is clearly far too simplistic. It is also clear that there were many back to Africa movements as well. Humans expanded sometimes because their old habitats were no longer viable. But, it seems, humans also explored and expanded into new territories from regions of plenty and where they maintained some contact with where they had come from. Probably, just because they could.
Related: Out of Africarabia posts