LOS ANGELES, CA (Catholic Online) - Denisovans were found mostly in East Asia, an archaic hominin species that lived in Siberia 40,000 years ago. Denisovans more than likely split off from the Neanderthal branch of the hominin family tree about 300,000 years ago. Very little else is known about their appearance, behavior or dress. Researchers have found genetic echoes of the Denisovans in modern residents of Pacific islands, such as New Guinea and the Philippines.

Denisovan genes are usually found in modern East Asian populations. Mattias Jakobsson, a professor of evolutionary biology at Uppsala University in Sweden says that the genetic signal is less strong than it is in the Oceanic islands such as the Philippines. On the Asian mainland, the genetic similarities to Denisovans are strongest in southern China and Southeast Asia.

"We are actually finding gene flow in Southeast Asia," Jakobsson says. "So it's not restricted to the Oceanian parts of the world."

Jakobsson along with his fellow researchers first ran complex computer simulations of genetic data to understand how the limited gene information collected in population genetics research, which includes just segments of DNA. The group then examined genetic data from more than 1,500 modern humans from all over the world.

It was determined that the Denisovan genome proved that Asians, especially Southeast Asians, have a higher proportion of Denisovan-related gene variants than other world populations except for the Oceanic islanders.

While Oceanians have about a 5 percent fraction of Denisovan-related ancestry, Southeast Asians have around 1 percent. In comparison, genes from modern non-African humans have about a 2.5 percent fraction of Neanderthal ancestry.

It's difficult to ascertain when the Denisovan and human interbreeding occurred, Jakobsson said, but since Europeans don't have Denisovan ancestry, it's likely the mating occurred around 23,000 to 45,000 years ago, after Southeast Asians and European populations diverged.

Jakobsson are working on further studies on early human genetics and the steps that led to the modern human genome. The more research accomplished, the more complex the genetic picture becomes, he said. Bits of genes are almost all that are left behind of some ancient populations, including the Denisovans, Jakobsson said.

"We don't really know what they looked like, how they behaved or anything like that," Jakobsson said. "It's really genetics that gives us an edge here."

© 2011, Catholic Online. Distributed by NEWS CONSORTIUM.