Thor Heyerdahl in Reverse

I found this piece on the earliest settlers of South America from Florida Atlantic University at Phys.org fascinating:

Using DNA from two ancient human individuals unearthed in two different archaeological sites in northeast Brazil—Pedra do Tubarão and Alcobaça—and powerful algorithms and genomic analyses, Florida Atlantic University researchers in collaboration with Emory University have unraveled the deep demographic history of South America at the regional level with some unexpected and surprising results.

Not only do researchers provide new genetic evidence supporting existing archaeological data of the north-to-south migration toward South America, they also have discovered migrations in the opposite direction along the Atlantic coast—for the first time. The work provides the most complete genetic evidence to date for complex ancient Central and South American migration routes.

Among the key findings, researchers also have discovered evidence of Neanderthal ancestry within the genomes of ancient individuals from South America. Neanderthals are an extinct population of archaic humans that ranged across Eurasia during the Lower and Middle Paleolithic.

Results of the study, published in the journal Proceedings of the Royal Society B : Biological Sciences, suggest that human movements closer to the Atlantic coast eventually linked ancient Uruguay and Panama in a south-to-north migration route—5,277 kilometers (3,270 miles) apart. This novel migration pattern is estimated to have occurred approximately 1,000 years ago based on the ages of the ancient individuals.

Findings show a distinct relationship among ancient genomes from northeast Brazil, Lagoa Santa (southeast Brazil), Uruguay and Panama. This new model reveals that the settlement of the Atlantic coast occurred only after the peopling of most of the Pacific coast and Andes.

“Our study provides key genomic evidence for ancient migration events at the regional scale along South America’s Atlantic coast,” said Michael DeGiorgio, Ph.D., co-corresponding author who specializes in human, evolutionary, and computational genomics and is an associate professor in the Department of Electrical Engineering and Computer Science within FAU’s College of Engineering and Computer Science. “These regional events likely derived from migratory waves involving the initial Indigenous peoples of South America near the Pacific coast.”

Researchers also found strong Australasian (Australia and Papua New Guinea) genetic signals in an ancient genome from Panama.

The DNA of the sweet potato has suggested to some that South America was settled from the Pacific hundreds of years ago. The human DNA seems to suggest that it took place millennia ago.