There is a new report about Monte Verde, an archaeological site in Chile. There is solid evidence that people were there 14,500 years ago – the earliest occupation of South America that we can be sure of – older than the Clovis culture of North America!
Further work, just published, suggests that there are artifacts at Monte Verde that are at least 18,500 years old. John Hawks talks about it, here
Remember also that A. there is a genetic evidence of a ghost population in some Amerindian groups, a population most closely related to the Onge (Andaman islanders), but also to other groups such as Melanesians and Philippine Negritos (Mamanwa). This component makes up one or two percent of the ancestry of Amazonian Indians. Also consider that the earliest known skeletons in the Americas, especially in Brazil, look a lot like Australo-Melanesians. Although I don’t we think we have any ancient DNA from those Brazilian skeletons yet.
It seems possible that a vaguely Andaman-like population, using a maritime strategy, crossed into American waters, moved down the Pacific coast, and eventually settled inland South America, well before the Amerindians we known showed up at Ellis Island. John talks about them “following the kelp road”.
There is another fact that helps in knitting these observations together. When in doubt, look at the map – it often tells you something.
Thing is, if you arrived so early, when deglaciation had barely begun, North America was a pretty crappy place, ice in Chicago and taiga down to the Gulf Coast. While on the other hand, parts of Brazil were pretty decent habitat for hunter-gatherers.
Suppose this happened. These guys didn’t start out as experienced big-game hunters. The Amerindians, originating in Beringia, were. So these hypothetical sort-of-Andmananese took a while to adapt to a continental lifestyle and never became awesome, extinction causing hunters. Their tool kit looks pretty simple.
You might compare them to the Australo-Melanesians that occupied Southeast Asia, before people from South China moved in and squashed them (with some admixing).
Here is looks like replacement by Amerindians with just a little admixture. Those Amerindians could easily spread over North America – they were good hunters and the climate was much improved by then.
How to tell if this story is correct? if we find a sufficiently old (C-14 dating) skeleton in Central or South America that has vaguely-Andamanese DNA, rather than Amerindian autosomal, we’ll know. Would take only a sliver of bone.