A new paper shows that it is likely that modern humans had left Africa by at least 177,000 years ago. The single Out-of-Africa theory is dying if not completely dead. Certainly some of the earlier excursions out of Africa may not have survived. I am still sticking to my narrative of the peopling of the world being mainly due to (at least) two waves of expansion from AfricArabia; one before the Toba eruption (74,000 years ago) and one after.
Hershkovitz et al, The Earliest Modern Humans outside Africa, Science 26 Jan 2018: Vol. 359, Issue 6374, pp. 456-459, DOI: 10.1126/science.aap8369
Abstract: Recent paleoanthropological studies have suggested that modern humans migrated from Africa as early as the beginning of the Late Pleistocene, 120,000 years ago. Hershkovitz et al.now suggest that early modern humans were already present outside of Africa more than 55,000 years earlier (see the Perspective by Stringer and Galway-Witham). During excavations of sediments at Mount Carmel, Israel, they found a fossil of a mouth part, a left hemimaxilla, with almost complete dentition.
The sediments contain a series of well-defined hearths and a rich stone-based industry, as well as abundant animal remains. Analysis of the human remains, and dating of the site and the fossil itself, indicate a likely age of at least 177,000 years for the fossil—making it the oldest member of the Homo sapiens clade found outside Africa.
The sensational discovery of modern humans in the Levant 177-194 thousand years ago should cause a rethink of the currently held Out-of-Africa orthodoxy.
By Out-of-Africa, I mean here the origin of anatomically modern humans, as opposed to the earlier origin of the genus Homo or the later origin of behaviorally fully modern humans.
Two main pieces of evidence supported the conventional OOA theory:
1. The observation that modern Eurasians possess a subset of the genetic variation of modern Africans.
2. The greater antiquity of AMH humans in the African rather than the Eurasian palaeoanthropological record.
Both these observations are in crisis.
1a. The oldest African fossil AMH is in North Africa (Morocco, Jebel Irhoud); modern genetic variation does not single out this region as a potential source of modern humans. In short, modern genetic variation has nothing to say about where AMH originated.
1b. Eurasians can no longer be seen as a subset of Africans, given that they possess genetic variation from Denisovans, a layer of ancestry earlier than all extant AMH. While it is still true that most Eurasian genetic material is a subset of that of modern Africans, it is also true that the deepest known lineage of humans is the Denisovan-Sima de los huesos, with no evidence for any deeper African lineage. Within humans as a whole, Africans possess a subset of Eurasian genetic variation.
2a. African priority received a boost by 0.1My by the redating of Jebel Irhoud last year. And, non-African AMH received a boost of 0.05My by the Hershkovitz et al. paper yesterday. A very short time ago, Ethiopia boasted the oldest AMH by 0.07My and now it’s tied with the Levant and beaten by Morocco. It’s a bit silly to argue for temporal priority based on the spotty and ever-shifting palaeoanthropological record.
2b. It is virtually untenable to consider the ~120,000 year old Shkul/Qafzeh hominins as a failed Out-of-Africa, since it now seems that they may have been descendants from the Mislya Cave population of >50,000 or even >100,000 years earlier.