A study conducted by the researchers at the Uppsala University found that people in East Asia share genetic material with Denisovans, who were named from the cave in Siberia where they were first found.
The study says that during human evolution our ancestors mated not only with Neanderthals, but also with other related hominids.
The lead researcher Mattias Jakobsson, who conducted the study together with Pontus Skoglund, said hybridization took place at several points in the evolution, and the genetic traces of this can be found in several places in the world.
Previous studies have found two separate hybridization events between so-called archaic humans (different from modern humans in both genetics and morphology) and the ancestors of modern humans after their emergence from Africa: hybridization between Neanderthals and the ancestors of modern humans outside of Africa and hybridization between Denisovans and the ancestors of indigenous Oceanians.
The genetic difference between Neandertals and Denisovans is roughly as great as the maximal level of variation among us modern humans.
Researchers demonstrate that hybridization also occurred on the East Asian mainland. The connection was discovered by using genotype data in order to obtain a larger data set. Complete genomes of modern humans are only available from some dozen individuals today, whereas genotype data is available from thousands of individuals.
Genotype data stems from genetic research where hundreds of thousands of genetic variants from test panels are gathered on a chip.
Jakobsson and Skoglund found that individuals from mainly Southeast Asia have a higher proportion of Denisova-related genetic variants than people from other parts of the world, such as Europe, America, West and Central Asia and Africa.
The Denisova-related gene variants were found in Southeast Asia and Oceania, but not in Europe and America, the researchers suggest that hybridization with the Denisova man took place about 20,000-40,000 years ago, but could also have occurred earlier. This is long after the branch that became modern humans split off from the branch that led to Neanderthals and Denisovans some 300,000-500,000 years ago.