Ancient human ancestors may have crossed a treacherous marine barrier and mated with modern humans.
The recent human relatives, the Denisovans, were able to cross a powerful marine current in Indonesia, called Wallace's Line, that separated European and Asian mammals from Australians, a University of Adelaide news release reported.
Denisovans line was mapped out only three years ago after researchers genetically analyzed a pinky finger bone from Denisova cave in northern Asia.
Researchers had found evidence of the Denisova's hybridization with modern day humans, but only in Indigenous populations in Australia and New Guinea, the link is very weak in most areas of Asia, even thought this is where researchers found the original fossil.
"In mainland Asia, neither ancient human specimens, nor geographically isolated modern Indigenous populations have Denisovan DNA of any note, indicating that there has never been a genetic signal of Denisovan interbreeding in the area," Professor Cooper, Director of the University of Adelaide's Australian Centre for Ancient DNA, said. "The only place where such a genetic signal exists appears to be in areas east of Wallace's Line and that is where we think interbreeding took place -- even though it means that the Denisovans must have somehow made that marine crossing," he said.
Researchers have also discovered an ancient human species called Homo floresiensis or "hobbits" in Indonesia, which showed them that there were more human ancestors walking the Earth at the time than they once thought.
"The conclusions we've drawn are very important for our knowledge of early human evolution and culture. Knowing that the Denisovans spread beyond this significant sea barrier opens up all sorts of questions about the [behaviors] and capabilities of this group, and how far they could have spread," Cooper said.
The next step is for the scientists to pinpoint when and how Denisovans were exposed to modern humans 50,000 years ago.
"Intriguingly, the genetic data suggest that male Denisovans interbred with modern human females, indicating the potential nature of the interactions as small numbers of modern humans first crossed
