A DNA Search for the First Americans Links Amazon Groups to Indigenous Australians | Science | Smithsonian – The DNA that links these groups had to come from somewhere. Because the groups have about as much in common with Australians as they do with New Guineans, the researchers think that they all share a common ancestor that lived tens of thousands of years ago in Asia but that doesn’t otherwise persist today. One branch of this family tree moved north to Siberia, while the other spread south to New Guinea and Australia. The northern branch likely migrated across the land bridge in a separate surge from the Eurasian founders. The researchers have dubbed this hypothetical second group “Population y” for ypykuéra, or “ancestor” in Tupi, a language spoken by the Suruí and Karitiana.
When exactly Population y arrived in the Americans remains unclear—before, after or simultaneously with the first wave of Eurasians are all possibilities. Reich and his colleagues suspect the line is fairly old, and at some point along the way, Population y probably mixed with the lineage of Eurasian settlers. Amazonian tribes remain isolated from many other South American groups, so that’s probably why the signal remains strong in their DNA.
The results line up with studies of ancient skulls unearthed in Brazil and Colombia that bear stronger resemblance to those of Australasians than the skulls of other Native Americans. Based on the skeletal remains, some anthropologists had previously pointed to more than one founding group, but others had brushed off the similarities as a byproduct of these groups living and working in similar environments. Bones can only be measured and interpreted so many ways, while genes usually make a more concrete case.
“The problem so far was that there has never been strong genetic evidence to support this notion,” says Mark Hubbe, an anthropologist at Ohio State University who was not affiliated with the latest study.