Human DNA tied mostly to single exodus from Africa long ago

Homo sapiens evolved in Africa about 200,000 years ago and went on to become great walkers. Prehistory Australia and New Guinea were connected by a land bridge that allowed human populations to migrate in and out, but once the ocean covered the bridge the Aboriginal ancestors got locked in isolated populations. The question, one of the biggest in human evolution, has plagued scientists for decades.

In the first comprehensive study of genetic diversity among Indigenous Australians, Eske Willerslev at the University of Copenhagen in Denmark and his colleagues found that different indigenous groups within Australia are genetically quite distinct, but that they are all descended from a single, founding wave of people from Africa. New research published Wednesday, Sept. 21, 2016 suggests that the genetic ancestry of people living outside Africa can be traced nearly completely to a single exodus of humans from that continent long ago.

The civilization reached the location and established a society there, being one of the only societies that can be traced back to the same place they're ancestors arrived to.

They found no evidence of substantial ancestry from an early African exodus in Papuans and other related populations such as indigenous Australians. But by conducting studies like these, where the latest genetic techniques are applied to understudied populations, researchers may soon be able to paint a complete picture of humanity's global dispersal. Yet until now scientists have sequenced entire genomes from very few people outside population centers like Europe and China.

Commenting on the Reich Lab study, Dr Metspalu told BBC News: "They do not detect an early Out of Africa, but they also do not reject it as long as it is just a few per cent in modern humans".

Each team of researchers tackled different questions about our origins, such as how people spread across Africa and how others populated Australia.

It might sound like papers 1 and 2 are down with the single out-of-Africa expansion and paper 3 says no way, there were at least two waves.

Further study is needed to puzzle out whether modern humans have ancestors from earlier waves of migration. These first modern humans to have traveled out of Africa would have gone to Southeast Asia and Australia.

These studies may be the first step towards confirmation of the common ancestor theory.

Though genetic evidence points to a single exodus, archaeological findings do not necessarily concur.

The researchers also looked for a mutation that might have occurred between 50,000 and 80,000 years ago, when human technology and culture took off, with advances in art, burial rituals and tool use.

Human remains found in caves on Israel's Mount Carmel were found to be about 115,000 years old.

One of the studies led by Harvard Medical School (HMS) geneticists sequenced samples from 142 smaller populations.

They found the evidence in the genes when a match between the extinct group and the Papua New Guineans occurred. Each of the three studies comes to its own conclusions on timing, but taken together, they pretty much agree. He joined David W. Lambert, a geneticist at Griffith University in Australia, who was already meeting with Aboriginal communities about participating in this kind of research. After further breaking down the gene splits, they concluded that the Papua New Guinea genome "originated as an independent expansion out of Africa about 120,000 years ago", Dr. Pagani told BBC News.

"Our results suggest that, rather than having left in a separate wave, most of the genomes of Papuans and Aboriginal Australians can be traced back to a single "Out of Africa" event which led to modern worldwide populations".

Meanwhile, Mait Metspalu of the Estonian Biocentre was leading a team of 98 scientists on another genome-gathering project. The populations died out within a few generations, ultimately contributing no more than a few percent of the genome to anyone alive today, the researchers say.

But a third said it found surviving human DNA from at least one, earlier, Africa migration.

"The vast majority of their ancestry - if not all of it - is coming from the same out-of-Africa wave as Europeans and Asians", said Dr. Willerslev.

Present-day people outside Africa were thought to descend from a group that left their homeland 60,000 years ago. "To have that credibility is really important to us as we know from our point of view that we've been here for thousands of years, but people look at our stories [of being here] as myth", said Colleen Wall, an Aboriginal elder and senior woman of the Dauwa Kau'bvai Nation.