Humans emigrate from Africa in multiple waves rathan one one: study

Genome sequencing of remote peoples of the Pacific and Australia is shedding light on how early humans moved out of Africa and spread across the world, New Zealand scientists said Thursday.

Genome sequencing of Papuan and Australian aboriginal people supported the theory that humans emigrated from Africa in multiple waves, rather than a single wave, and possibly earlier than previously believed, they said.

Some theories suggested that non-Africans could trace their ancestry back to a single migration event around 40,000 to 75,000 years ago.

But Massey University molecular anthropologist Professor Murray Cox, who co-authored a new international study, said it uncovered an earlier and now largely extinct wave of humans that moved from Africa to Eurasia between 100,000 and 120,000 years ago.

While this early wave of humans was extinct, DNA analysis of modern Papuans revealed at least 2 percent of their genetic material was retained from the earlier population, Cox said in a statement.

"The study is able to provide some remarkable results and puts forward a strong case for more investigations into the DNA of smaller, more remote ethnic groups," said Cox.

"These are under-explored regions from a genetic standpoint, as traditional studies have focused mainly on the standard categories of Europeans, Asians and Africans. While these have been a treasure trove of knowledge of our early movements and makeup, it's now time to cast the net wider and discover what these other regions have to tell us."

Further studies would clarify the timing and route followed during such an early expansion and the data would be used to analyze modern human immunity to certain diseases or tolerance to certain substances.

University of Otago bioanthropologist Professor Lisa Matisoo-Smith, who took part in an international genome analysis of modern Aboriginal Australians and modern Papuans -- the Australians' northern neighbors, said the study showed the Aboriginal Australians and Papuans split from Europeans and Asians about 58,000 years ago.

They also found that Aboriginal Australians and Papuans later diverged around 37,000 years ago, long before the prehistoric Sahul continent separated into Australia and New Guinea due to rising seas, some 10,000 years ago.

"The genetic diversity among Aboriginal Australians is amazing," Matisoo-Smith said in a statement.

"Perhaps because the continent has been inhabited for such a long time, we find that groups from southwestern desert Australia are more genetically different from groups of northeastern Australia than are for example Native Americans and Siberians, and this is within a single continent." Endit