Scientists from the National University of Busan (South Korea) and the University of Naples (Italy) discovered that the increase in carbon dioxide in the atmosphere and the consequent warming of the climate contributed to the interbreeding of different ancient human species: Homo sapiens, Denisovans and Neanderthals. The research was published in the journal Science.
In the DNA of modern man (homo sapiens) traces of transitions preserved with other species: Neanderthals (Homo neanderthalensis) and Denisovans (homo denisovan). In 2018, scientists announced the discovery of an individual who lived 90,000 years ago, later named Denny. Apparently his mother was a Neanderthal woman and his father was a Denisovan man.
In the new study, the scientists used data on ancient humans, including genetic data, as well as climate modeling in antiquity using a supercomputer. The team found that Neanderthals and Denisovans had different climate preferences. It turned out that Denisovans were more adapted to cold conditions, including the tundra, and Neanderthals to more temperate forests and grasslands.
That means their habitats are geographically divided: Neanderthals generally preferred the southwest of Eurasia, while Denisovans preferred the northeast, the scientists explained. But during the warmer periods, when the carbon dioxide accumulated in the air and the glaciers melted, the humanoid habitats began to overlap. As a result, more meetings between them occurred, increasing the likelihood of interbreeding.
The results of the analysis are consistent with known episodes of interbreeding of ancient humans, which occurred 120, 78 and 90 thousand years ago. The study also made it possible for the first time to assess where Denisovans may have lived.
“We found, surprisingly, that northern Europe, as well as regions in Russia and China, could be a suitable environment for them,” the scientists said.
It is unknown whether Denisovans lived west of the Altai Mountains, but this can be confirmed by genetic analysis of European populations. Additional climate data are likely to explain the hybridization events that occurred between 210,000 and 320,000 years ago.
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