At https://phys.org/news/2019-07-southeast-asia-crowded-archaic-human.html … SE Asia was crowded with archaic human groups long before modern humans turned up – going back 50,000+ years ago. This is according to a new study in PNAS. The theory is now that the ancestors of modern humans living in the area met and genetically mixed with the various archaic groups by reason they have left behind a small genetic signature. We may note the smallness of that signature is convenient as it allows the Out of Africa mantra to be defended. This is that modern humans fanned out across India and SE Asia and reached Australia at around 50,000 years ago (although variations in the dates have been suggested in earlier studies). The archaic groups included Neanderthal and Denisovan admixtures and the point of the study was to discover when the hybridisation may have occurred, geographically. As that is determined by the discovery of skeletal material such as skulls one may suspect it is incomplete. Nevertheless, we have some interested maps – and see also https://archaeologynewsnetwork.blogspot.com/2019/07/out-of-africa-and-in… …
Traces of admixture are preserved in genomes. The passage of modern humans via India into SE Asia has been put together via computer technology. The recent discovery of the survival of archaic genes in various localities such as New Guinea has caused this major rethink and subsequent reassessment of human population movements. This is said to have happened in a very short period of time and in order to keep the theory alive they have cast doubt on a recent date at the Aboriginal site of Madjedbebe rock shelter in Arnhem Land which is dated 65-80,000 years ago (and somewhat takes the shine off their carefully worked out chronology). They do of course have a dilemma as the evidence is that archaic humans continued to live in these regions up until 50,000 years ago (itself a modern stretch of what was formerly a 40,000 years ago date). The evidence seems to be that modern humans have been in the region from at least 50,000 (formerly 40,000) years ago but archaic humans disappeared at the same time (as in the contemporary disappearance of Neandertals in Europe and their replacement by modern humans). The difference in SE Asia is that four different archaic human groups were involved – possibly even a surviving group of Homo erectus (or a variant of that more ancient archaic human group). These include the Denisovans, and Neanderthals. What of course is missing from this re-assessment is any mention of catastrophe. A major event around 40,000 years ago appears to have led to the disappearance of megafauna in Australia – and we may suppose, if we so wish, to assume there was also a crash in the population of humans (of the archaic variety). This means a bottleneck in genes with the survivors the so called modern humans (retaining archaic DNA). It is a fact that the further you go back the less genetic material survives and it is more recent genetic changes (the last few thousand years) that dominate most genomes. This means most of the older DNA has been diluted over time. The link above even mentions a skeleton from Russia dating back 40,000 years ago that had much more Neanderthal DNA than exists in modern skeletal material. The Out of Africa theory (a dispersal from around 55,000 years ago) is mentally fixated on the idea that all humans are related and their origin post dated the eclipse of the more archaic groups (that perhaps had the time to diverge from each other and evolve distinct differences in race etc). Variety is the spice of life they say but apparently not in Out of Africa. The idea that modern human groups may have evolved out of the archaic groups (as a result of a bottleneck) is not at the moment part of the debate – or so it would seem. All kinds of twists and turns in order to keep the Out of Africa mantra alive is to be expected. Lots of pen and ink and typeface has been expended on the theory and it isn't going to go away in a hurry as this new study illustrates.
See also https://phys.org/news/2019-07-africa-archaic-human-pot.html … Out of Africa into an archaic human melting pot.