Anthropology

First, my apologies for a long post on this, but your link triggered my long interest in early settlements of the Americas.

The letter to the editor in your link cites Japanese archaeologist Nakazawa on possible layer intrusions by rodents making the 16,000 BP questionable. He could be right about that but there's a much larger picture than the letter in the link depicts.

I've been interested in a Pacific route to the Americas ever since James Adovasio's excavation of the Meadowcroft Rock Shelter in PA found dates of 14,000 BP and earlier. He faced the same scrutiny and objections about dates and layer contamination, but his dates have held up over the years.

More interesting to me is a discussion that I had years ago with Adovasio's staff about a Pacific migration route and possible maritime and land culture along the Pacific Rim from Japan through Beringia to North America. So I checked some info from the link in your post.

I'm not able to agree or disagree with objections on the dates. But I remember Adovasio's experience. The letter says the earliest possible date is 14,600 BP based on fire evidence at the Cooper's Ferry site, which is not yet proven to be human made. That is still a pre Clovis date which opens up the larger and more significant picture (IMO) of a Pacific route, which gets to the next point in the letter about Japan being the source for similarities in the stone point technology at Cooper's Ferry.

The letter identifies the Cooper's Ferry points as part of the Western Stemmed Point technology dated to 11,000 BP at other sites. But there are older sites that are part of the Western Stemmed Point technology and others very similar to it along the Pacific Rim and even as far south as Chile.

The letter says that the Japanese stemmed points date to 13,000 BP so if the Cooper's Point dates of 16,000 BP and 14,600 BP are correct, the technology for the Cooper's Ferry points could not have come from Japan. The letter also says that it is very unlikely that the Japanese technology later spread all the way to North America once it did develop. So it says that the similarity of technology is due to coincidental development in both places.

But the timeline for Beringia and two DNA haplogroups show that an indirect technology exchange was possible. I am NOT saying that it did happen, only that it is possible. People were in Beringia 25,000 years ago. The Pacific Coast of North America was ice free by 16,000 to 18,000 years ago, much earlier than the ice free land route of 11,000 years ago.

There is DNA evidence in 2 haplogroups of back migration from America to Asia. One of them is in the 13,000 BP to 10,000 BP timing for technology exchange between Asia and northwestern North America. The direction of migration is wrong for carrying technology from Asia to North America, but it does demonstrate continued contact between the two continents via Beringia.

Here's a map of back migrations:

https://en.wikipedia.org/wiki/Beringia

Here's an article about Western Stemmed Point technology similarities from Asia to South America that supports a possible Pacific migration route and stone point technology techniques from Japan to South America. It does not prove that that's what happened, but it does make it look more probable.

https://www.science.org/content/article/spear-tips-point-path-first-americans