It doesn’t seem like an outlandish claim that many waves of humans tried and failed to colonize the world, until one succeeded. I would find it harder to believe that the first to leave Africa got it right first time.
Dr. Skoglund also said it would be strange for non-African ancestors to have arisen about 47,000 years ago while modern humans in Asia and Australia dated back 100,000 years. The sites in question could have been incorrectly dated, he said, or people could have reached Asia and Australia that long ago, only to die out.
see:
(2016) https://www.abc.net.au/news/science/2016-09-22/world-first-s...
(2017) https://www.nature.com/articles/nature21416
etc.
Such results are inherently noisy and subject to assumptions. The further back in history you go, the less accurate and reliable the results will be. Ancient DNA comes with its own issues and assumptions, but it helps with the accuracy of the results. Instead of trying to infer something that happened thousands of generations ago, you may now be only hundreds or even tens of generations from the split.
The clearest way forward would be sequencing Aboriginal Australian DNA from tens of thousands of years ago. Then you could get a more accurate estimate for the split between that population and other sequenced ancient populations.
The people that ended up in Australia were some of the earliest anatomically modern humans that successfully made the trip out and for some reason or the other were not really able to colonize Europe/Asia and kept venturing south until they ended up in Australia
Other later waves probably made it to the middle east and went back. Some made it a bit into Europe and some of asia. But it wasn't until relatively recent times, that we got waves that finally got a foothold in Europe/Asia and eventually outlasted other homo species that had dominated those areas for a 100,000 years.
I am not an anthropologist. I can't prove anything I wrote. I am just using my own common sense and the evidence that has so far been published.
Any people that did settle in Europe to the north during that first pass through further south some 70K years ago very likely were pushed back by the worsening conditions preceding the advance of the Last Glacial Maximum (dry very dusty air, poor vegetation .. and later ice everywhere).
Following the path of best land with least resistance led to following the tropics mostly by land, consistent year round conditions, no winters to store food for, etc.
Your comments do not apply with any force to this particular study.
It’s more likely competitive pressure forced them to expand out further because to a small group, even a small conflict with a neighboring tribe that costs them a few of their fittest members would be particularly traumatic and risky. It’s just easier and safer to migrate.
Archaic humans made it out to South East Asia over a million years ago back when the sea hadn’t even risen to form the major islands like Indonesia. Migration is in our DNA.
That's distinct from making a claim, an assertion with supporting evidence.
To make a claim, we would want evidence, and the evidence here would be a genetic isolation (lack of chronological overlap, synonymous with lack of interbreeding) of ancient Asian humans from ancient African humans. This requires sequencing a lot of ancient Asian DNA, which seems not to have happened yet. We barely have a cohesive evidence supported grasp of Neanderthal interactions in Europe, but are gradually updating to support more and more absorption by interbreeding.