According to the scientists, Neanderthals are long gone. However, that doesn’t change the fact that modern humans spent a lot of time with their cousins, and were even interbreeding with them. However, modern humans also mated with other human species. The new study suggests that there was another archaic species, the Denisovan cousins, that Homo sapiens are believed to have bred with at least twice throughout history.
The Denisovans were originally discovered in 2010. Scientists discovered bones in the Denisova cave in Russia’s Siberia, and after close-up examination, they determined that their bone fragments belonged to neither Homo sapiens nor Neanderthals, even though, it’s been well-established that both species used to live in the cave.
In the most recent research paper published in the journal Cell on Thursday, researchers said that they “found two distinct episodes of Denisovan genetic intermixing, or admixing, between” Homo sapiens and Denisovan cousins. Denisovans are at times qualified as subspecies of Homo sapiens.
Researchers from the University of Washington, Seattle determined these results after they decided to compare the whole genome sequences of Homo sapiens with that of the Denisovans. They were using the population from today’s East Asia and Oceania regions to make the comparison as accurate as possible. Those populations are known to contain Denisovan genes.
“What was known already was that Oceanian individuals, notably Papuan individuals, have significant amounts of Denisovan ancestry. The genomes of modern Papuan individuals contain approximately 5 percent Denisovan ancestry,” Sharon Browning from the university and senior author of the study, said in a statement on Thursday.
Scientists associated the existence of Denisovan genomes in different parts of Asia to their migration from Oceania.
“But in this new work with East Asians, we find a second set of Denisovan ancestry that we do not find in the South Asians and Papuans. This Denisovan ancestry in East Asians seems to be something they acquired themselves,” Browning explained.
In the present day, modern East Asian populations closely resemble the Denisovan genome, even closer than people from Papua.
“When we compared pieces of DNA from the Papuans against the Denisovan genome, many sequences were similar enough to declare a match, but some of the DNA sequences in the East Asians, notably Han Chinese, Chinese Dai, and Japanese, were a much closer match with the Denisovan,” she said.
Browning and her team offered various theories. One of them includes that a group of southern Denisovans had been interbreeding with modern humans who lived in Oceania. On the other hand, a group of Denisovans living in the north mated with East Asian modern human populations.
Now that their study titled “Analysis of Human Sequence Data Reveals TwoPulses of Archaic Denisovan Admixture,” is published, the researchers are going to focus on studying different human populations that were spread across the globe. They are looking to find evidence of more interbreeding of modern humans and their Denisovan cousins.