Four Types of South American Indians
After crossing the Panama land bridge over 10,000 years ago, Amerindians split up to evolve mostly separately in the four main environments of South America.
A news study in Science, From North Asia to South America: Tracing the longest human migration through genomic sequencing, says there are four main types of South American Indians who split apart about 10,000 to 13,900 years ago after crossing the Panamanian Isthmus from North America:
Andeans (who are adapted to high altitude),
Amazonians (who live in the rain forest)
Chaco Amerindians (who live in the dryer region south of the Amazon, such as Paraguay), and
Patagonians (who live in the cold far south).
The Amerindians of north South America such as Columbia and Venezuela tend to be a mixture of the four types. Is the because of back migration or because they more resemble the basal newcomers and haven’t gone through as much subsequent evolution into different types?
The authors didn’t seem to have any data on that rare trace of Old World ancestry first discovered a decade ago that is sometimes found in Amazonians and resembles that seen in Andamanese or Papuans on the other side of the world. So far, nobody has managed to come up with a convincing explanation for how it got to South America.
They didn’t have data from the USA, probably because American laws make it an ordeal to sample American Indians, living or dead.
How strong is the evidence that South American dna is linked to New Guinea? Seems so implausible. Maybe the geneticists got this one wrong.
I wonder if weaker tribes were pushed to the least amenable regions of the Americas and that affected their outlook. For instance, the Patagonians may have been weak to be pushed so far south. The Apaches were pushed to inhospitable mountain-desert regions due to weakness yet they became some of the most fierce Indians in the Americas.