Denisovans may have interbred with mysterious group of ancient humans

For only the second time, researchers have been able to obtain the complete genome of the Denisovans, a group of ancient people who lived in Asia. DNA was extracted from a single 200,000-year-old tooth found in a Siberian cave.

The genome shows that there were at least three populations of Denisovans with different histories. It also shows that early Denisovans interbred with an unidentified group of early humans, as well as with a hitherto unknown population of Neanderthals.

“This is a sensational article,” says David Reich at Harvard University.

“This research has really expanded my understanding of the Denisovan universe,” says Samantha Brown at the National Research Center for Human Evolution in Spain.

The Denisovans were first ancient humans described only by DNA. A finger bone fragment from Denisova Cave in Siberia contained DNA different from that of modern humans or Neanderthals from western Eurasia. The genome revealed that Denisovans interbred with modern humans: People in Southeast Asia, including the Philippines and Papua New Guinea, carry Denisovan DNA.

Since the first reports in 2010, researchers have identified a handful from other Denisovans, all from East Asia. In June, a skull from Harbin, China. was identified as Denisovan using molecular evidenceshowing for the first time what the face of a Denisovan looked like. However, although DNA fragments were found in several samples, the original sample was the only one that was found to have a high-quality genome.

Researchers led Stephane Peyren the Max Planck Institute for Evolutionary Anthropology in Germany has added another one. (Peyreigne declined to be interviewed because the study has not yet been peer-reviewed.)

In 2020, the team discovered a single molar belonging to a Denisovan male in Denisova Cave and sequenced the entire genome based on the preserved DNA.

Based on the number of mutations in the genome and comparisons with other ancient humans, the team estimates that this person lived about 205,000 years ago. According to this, the sediments in which the tooth was found are dated to 170,000–200,000 years ago. In contrast, the other high-quality genome belongs to a Denisovan who lived 55,000–75,000 years ago, meaning the new genome reveals a much earlier stage in Denisovan history.

Based on comparisons with other remains from Denisova Cave, the team says there appear to have been at least three distinct Denisovan populations. The oldest group included a male whose tooth was analyzed. A second group replaced the older population in Denisova Cave thousands of years later.

“Understanding how early Denisovans were replaced by later Denisovans highlights an important human event,” says Qiaomei Fu at the Institute of Vertebrate Paleontology and Paleoanthropology in China.

A third group, not represented in the cave, interbred with modern humans based on DNA analysis. In other words, all of the Denisovan DNA in modern humans comes from a Denisovan population about which we know little or nothing.

The new genome shows that Denisovans interbred repeatedly with Neanderthals, who sometimes lived in or near Denisova Cave. Importantly, the genome includes traces of a Neanderthal population that predates male Denisovans by 7,000 to 13,000 years. These traces do not match any known Neanderthal genomes, suggesting that Denisovans interbred with a group of Neanderthals that has not yet been sequenced.

Denisovans also appear to have interbred with an unidentified group of ancient humans that evolved independently from Denisovans and modern humans over hundreds of thousands of years. One possibility is The man stood upwho, according to modern data, was the first person to migrate outside of Africa and lived even on the island of Java in Indonesia. However, the DNA has not yet been recovered. H. erectusso we can't be sure.

“It’s endlessly exciting that we continue to discover these new populations,” Brown says.