At https://phys.org/news/2021-04-genome-analysis-reveals-unknown-ancient.html … human remains dated 45,000 years ago are said to reveal an unknown migration into Europe. As an add on they suggest these people may even have intermixed with Neanderthals – who did not disappear until 40,000 years ago. Actual tangible evidence of mixing, apart from genetic assumptions that they must have mixed, otherwise why would modern people have a vestige of Neanderthal genes in them. The idea also involves the dates produced by the research. These appear to be an artifact of the methodology, namely the Bayesian system. This was introduced in order to breach the 40,000 year barrier on C14 dating. They introduced multiple methodologies and came up with an average, hence the term Bayesian. In a nutshell, although it is not quite as simple as that.
The remains were discovered in a cave in Bulgaria and the interesting point to be taken from it is that they had characteristics more commonly associated with East Asians and the people that settled America [who had a Siberian heritage]. Whilst the latter are not thought to have reached America south of Beringia until the end of the Late Glacial Maximum, this particular inroad towards Europe [from central Asia perhaps] took place 45,000 years ago. Prior to the Late Glacial Maximum. Hence, it is not the same folk movement invoked by Paul Reich a few years ago. It is somewhat earlier. One can see a connection with the people of central and eastern Asia during the Late Glacial Maximum, the folk movement pinpointed by Reich, but the origin of the Bulgarian movement has yet to be ascertained.
The point I wish to make, as an add on to the research, is that it is more legitimate to think in terms of the 45,000 years ago date being coeval with the 40,000 years ago date – the buffers of C14 methodology. In other words, something occurred at around 40,000 years ago, involving a huge injection of C14 into the atmosphere [hence the buffers], creating a plateau in which C14 dates clustered somewhat like they did during the Hollstein Plateau in mid first millennium BC. This date is associated with the disappearance of the Neanderthals [and a die off of various other mammals] in association with what is known as the Laschamp Magnetic Excursion. This was in effect a magnetic reversal that lasted for a few hundred years before reversing itself back again. What might cause such magnetic excursions is open to debate and has yet to be adequately explained. Not only that the Laschamp event, although first noticed from western Europe, is now considered a global event. If it was associated with upheaval in the physical world, as suggested by the disappearance of Neanderthals and other people, as well as big changes in the animal world, one might jump to the conclusion these newcomers arrived in Bulgaria as a result of fleeing from troubles in their unknown point of origin.
Another point I picked up from the piece is that Neanderthal genes in modern humans occur in short blocks – but in longer blocks the further back in time you go. In other words, as explained by Reich, inherited genes reduce over generations – and Neanderthals lived a long time ago and therefore we only have a negligible amount in our modern genomes. Hence, human remains closer to the Neanderthal world have a lot more Neanderthal within them as they had not been diminished by too many generations.
See also https://doi.org/10.1038/s41586-021-03335-3 … and https://doi.org/10.1038/s41559-021-01443-x …
See also www.sciencedaily.com/releases/2021/04/210407114205.htm … this time we have interactions between Neanderthals and Denisovans and modern humans around 37,000 years – in SE Asia.