Ancient peoples in South America had both Denisovan and Neanderthal DNA -- and we have no clue how it

[wnylib]

3. Agree. I don't know why this article

makes it seem like there is some great mystery here.

I question a few things in the article. It says that HD (Denisovan) DNA in Brazil is from 40,000 years ago, but does not clarify the statement. I personally think that people were probably in the Americas much earlier than has usually been believed. But I don't know of any specific confirmation that is accepted for 40,000 years ago. The DNA from HD could trace back to 40,000 years ago without the people themselves arriving in South America until later. It might be possible to clarify which is the case by looking at available mutation records in the DNA of HD in modern populations that have HD DNA.

The claim in the article that HN (Neanderthal) was in Europe and therefore its presence in Asia is mysterious is just not true. There are HN remains in Asia. There are sites in Asia where both HD and HN lived. Asians and the Native people of the Americas have higher HN DNA than Europeans.
https://www.archaeology.org/issues/60-1301/trenches/311-hominin-neanderthals-humans-siberia#:~:text=According%20to%20David%20Reich%2C%20a,%2C%20on%20average%2C%20than%20Europeans.

The Australasian DNA is interesting, since they are associated with southeastern Asia and the Beringia route is in far northeastern Asia. But ancient Asian migrations and consequent intermating can account for that. In fact, there is already evidence of that. The ancient Jomon people of Japan were related to Polynesians.

This article on the Australasian DNA in South America gives likely scenarios for how it shows up there, but not in North America.

https://www.science.org/content/article/earliest-south-american-migrants-had-australian-melanesian-ancestry