Multiple hominin dispersals into Southwest Asia over the past 400,000 years:
We have identified at least five pulses of human dispersal into northern Arabia, each associated with a phase of decreased aridity. The differences in material culture between these phases—with two phases of Acheulean technology and then three distinct forms of Middle Palaeolithic—suggests that diverse hominin populations, and probably even species, were expanding into the region at different times…
From the supplements:
Little is known of the Pleistocene fauna of southern and eastern Arabia, but the repeatedly distinctive, localised, character of material culture suggests that crossing the Red Sea at the Bab al Mandeb was not a primarily dispersal route and that instead populations filtered through northern Arabia. In northern Arabia the growing fossil record suggests repeated connections to Africa across a contiguous grassland zone through the southern Levant which formed during repeated humid episodes (discussed in SI 10). To that we can add significant aspects of material culture which we have reported in this paper. The absence of Acheulo-Yabrudian assemblages in northern Arabia, and the southern Levant, suggests that the Late Acheulean in this area relates more to Africa than to areas to the north. Likewise, with the early Middle Palaeolithic at KAM-4 (Assemblage C of the Northwest Lake) both technological features (such as the methods of Levallois surface preparation, see SI 7) and quantitative characteristics in terms of PCA of Levallois flake shape situate the assemblage between the Levantine Early Middle Palaeolithic the early Middle Stone Age in East Africa (SI 9)…
…The possible MIS 3 presence of Neanderthals in Arabia may suggest that they expanded further south than previously thought, and highlights that there is currently little clarity on where the main pulse of admixture between Homo sapiens and Neanderthals occurred, beyond probably Southwest Asia broadly.
As a closing note, we emphasise that as well as our results being consistent with repeated pulses of hominin dispersal out of Africa into Southwest Asia, the possibility of movement in the reverse direction should be kept in mind. Given factors such as current uncertainty on the background to the earliest known Homo sapiens in Africae, and discussions on the possible
involvement of a hominin closely related to Homo antecessor as an ancestor of our species, currently only known from Eurasia, as a precursor to Homo sapiens, building reliable records for the later Quaternary in Southwest Asia is not only important for understanding ‘out of Africa’ dispersals, but also for ‘into Africa’ dispersals.
Brilliant paper. It’s all coming together very nicely.
So now, AMHs in northern Australia by 60-65kya, and in southern China by 120kya, become possible.
But where’s the genetic trace, in us, the later OoA’s? Do they mean to suggest AMH are themselves the result of some kind of reflex population that returned to Africa? I just don’t get how you reconcile a 60k divergence date for Australians when 40-ish (iirc, anyways) is the split between East and West, especially when Australians are a subset of the former.
Over the past few years I’ve seen more and more papers come out which date the beginning of the genetic divergence between Eurasians and Africans to around 100,000 years ago, which also happens to align roughly with the formation of CT and L3. Regardless of the bottleneck which impacted the OoA group between 55,000-70,000, it seems fairly clear that genetically speaking the ancestors of what would become Eurasians were clearly well diverged from Africans for a long time before “OoA” itself.
I think people who get confused about the 60-80,000 year old traces humans in Australia or China are missing the bigger picture. These earlier “failed dispersals” are (possibly) part of range expansions of a human population that was already well established in Eurasia, probably in Southwest Asia, and not direct immigrants from Africa. Given what seems to be indicated by the aforementioned divergence dates between Africans/Eurasians, I think sometime around 100k or after a group of humans wandered out of Egypt to SW Asia and became relatively well-established, until the extreme aridification of MIS 4 (around 60,000-70 years ago) drove them to virtual extinction (the classic OoA bottleneck), but the ensuing climate amelioration of MIS 3 (55,000 years ago) allowed them to recover and gradually colonize the rest of the world.
“I just don’t get how you reconcile a 60k divergence date for Australians” – I didn’t say that.
Ancestors of Australians alive today became genetically isolated only 37kya.
I’m very sceptical of AMH in Australia before 50K B.P. and
in general think that AMH in SouthEast Asia before
55K B.P. is implausible (though there may be a pulse
much older (more like 200K B.P.)
See “How old are the oldest Homo sapiens in Far East Asia?” (Hublin 2021)
for a sceptical review by a real expert, and ref 11 of that paper for
a debunking of the 60K Madjedbebe Australian site.
If AMH reached Australia/Papua in 60K they
a) failed to disperse
b) contributed little or no genetics to later humans.
Thanks for the references.
In Ref. 11, I could not help but be amused by this statement: “leaving Madjedbebe as the only remaining candidate despite intensive search throughout Australia since 1990 for similarly old sites.” I’m confident you have a good idea how large Australia is, and how much of it is very sparsely populated and verging on unsurvivable. The idea of an intensive search of the whole country is really very funny. It’s obviously impossible. There is also the point that many early sites would now be underwater.
In an odd way, Aboriginal people would not be too hostile to a debunking of the claimed age of Madjedbebe. It is a big thing with them (us) that they (we) were the first people in Australia, for self-evident reasons, and comfortable as long as it was a very long time ago, so not too bothered whether it was 50kya or 60kya, or even just 37kya of genetic isolation. The idea of an early group that made it to Australia but did not survive and left no ‘genetic legacy’ in modern Aboriginal people would actually not be too popular. The culture/history wars being what they are, it would quickly be jumped on by the ‘anti’ crowd.