Neanderthal and Denisovan DNA Discovered in Ancient South Americans

Scientists investigating the genomes of ancient South Americans have made a surprising discovery: the presence of DNA from Neanderthals and Denisovans, two species of humans that are now extinct.

The findings complicate our understanding of ancient South Americans and their ancestries.

It's the first time that Denisovan or Neanderthal ancestries have been reported in ancient South Americans.

The research is published this week in the Proceedings of the Royal Society B. "The presence of these ancestries in ancient Native American genomes can be explained by episodes of interbreeding between anatomically modern humans and Neanderthals and Denisovans, which should have occurred millennia before the first human groups entered the Americas through Beringia," said Andre Luiz Campelo dos Santos, an archaeologist at Florida Atlantic University and the study's lead author, in an email to Gizmodo.

In the recent work, the team compared genomes from ancient human remains found in Brazil, Panama, and Uruguay with ancient remains from across the United States, Peru, and Chile.

Two ancient whole genomes from teeth found in northeast Brazil that were included in the study were newly sequenced.

In addition to the ancient human genomes featured in the analysis, the team looked at present-day worldwide genomes and DNA sequences taken from Denisovan and Neanderthal remains from Russia.

Perhaps most intriguingly, the analysis revealed chunks of Neanderthal and Denisovan DNA in the ancient South American genomes, as well as Australasian signals in the remains of one individual from Panama.

The Australasian signal was previously detected in ancient remains in southeastern Brazil and is present today in the Sirui people of Amazonia.

The ancient individuals in Panama and Brazil had more Denisovan ancestral signals in their genomes than they did Neanderthal-specific ancestry.

Santos said there was no evidence of the Australasian signal in ancient North American remains, which suggests ancient Australasians may have gotten to the Americas without crossing Beringia.

As more ancient genomes are sequenced, scientists can develop a more complete portrait of how humankind dispersed across the continents, and how much of what makes us human is actually not from Homo sapiens at all.