At https://www.livescience.com/archaeology/human-evolution/the-first-americans-had-denisovan-dna-and-it-may-have-helped-them-survive … The first Americans, or what is thought to be the first humans to colonise the American continent, possessed Denisovan DNA. In small amounts of course as the Denisovans go back a long way and each generation loses a bit ot its oldest DNA inheritance. The Denisovans died out about the same time as the Neanderthals, between 50 and 40,000 years ago. We are told this is another proof than Neanderthals and Denisovans mated with modern humans. Or did the Neanderthal/Denisovans morph into modern humans?
We already know from David Reich and his genetic colleages that the First Americans can be traced back to northern Asia – and perhaps, even central Asia. That means humans migrated into the Americas during the Late Glacial Maximum – but the timing of their arrival is a matter of dispute. Reich also claimed other groups moved westwards, into what is now Europe and the Russian steppe zone. No doubt they also moved southwards into central Asia – but how far southwards is open to conjecture. This all seems to have occurred during the Late Glacial Maximum, as opposed to the period following the end of the Ice Age as once dogmatically asserted. After all, at that time the Bering land bridge existed. It is now submerged. The Arctic Ocean was also not as extensive as it is nowadays. Mammoths were left stranded on islands in the Arctic zone – especially in regions close to the Bering land bridge, such as Wrangel Island. In other words, humans could have crossed the Arctic by boat. However, the research is focussed on mating between the various groups, so a lot of speculation is made. Curiously, the geneticists advanced a rather complicated picture of Denisovans first mating with Neanderthals and the latter mating with modern humans. This idea is put forward even though little DNA research in eastern Asia has taken place. Nowhere near the amount of studies as in Europe, for example. Hence, the First Americans seem to possess both Denisovan and Neanderthal genes. No mention of Homo erectus.