Man's ancestors mated with Neanderthals and other related hominids during human evolution, according to a new study.
The study found that people in East Asia share genetic material with Denisovans, a species of human who got there name after the cave in Siberia in which they were discovered.
The study, which was conducted by Professor Mattias Jakobsson and a graduate student of Uppsala University in Sweden, say that hybridisation took place at several points during human evolution and the genetic traces of which can be seen all around the world.
"We'll probably be uncovering more events like these," said Professor Jakobsson
"Previous studies have found two separate hybridisation 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.
"There was hybridisation between Neanderthals and the ancestors of modern humans outside of Africa and hybridisation between Denisovans and the ancestors of indigenous Oceanians.
"The genetic difference between Neanderthals and Denisovans is roughly as great as the maximal level of variation among us modern humans."
The connection was only made after scientists used genotype data - complete genomes data from thousands of individuals instead of just a few - in order to obtain larger data.
The scientists from Uppsala also say that hybridisation also occurred on the East Asia mainland.
"We 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," said Jakobsson.
"The findings show that gene flow from archaic human groups also occurred on the Asian mainland."
Skoglund added: "While we can see that genetic material of archaic humans lives on to a greater extent than what was previously thought, we still know very little about the history of these groups and when their contacts with modern humans occurred."
Since they found Denisova-related gene variants in south east Asia and Oceania, but not in Europe and America, the researchers suggest that hybridisation with Denisova man took place about 20 million years ago, but could also have occurred earlier.
This occured long after the branch that eventually became modern humans split off from the group that led to Neanderthals and Denisovans some 300,000 to 500,000 years ago.
"With more complete genomes from modern humans and more analyses of fossil material, it will be possible to describe our prehistory with considerably greater accuracy and richer detail," said Prof Jakobsson.