The vast majority of current populations would be the descendants of a single wave of migrants who left Africa about 80,000 years ago, according to separate studies published Wednesday in the British journal Nature.
There are currently two opposing theories in the scientific world when it comes to the origin of the variety of populations of humans across the globe.
The first is that our ancestors left their African cradle in one great wave of migration, about 80,000 years ago. According to this theory, all non-African humans in the world would have a single origin.
The other is the multiple-wave scenario, with a first migration dating to about 120,000 years ago. These first modern humans to have traveled out of Africa would have gone to Southeast Asia and Australia.
A second wave, later, would have populated the Eurasia.
To feed the findings of the three studies released Wednesday, the DNA of nearly 800 individuals, reflecting human diversity, has been sequenced.
For the first, David Reich of Harvard Medical School in the United States and his team studied the genomes of 300 people from 142 different populations, scattered around the world.
“We have show that indigenous Australians and New Guineans are from the same migration as other non-Africans in the world,” says the study.
A similar conclusion is made by Eske Willerslev, a researcher from the University of Copenhagen, Danemark and his colleagues. Their genetic analysis of 83 Australian Aborigines and 25 people of Papua New Guinea show that the populations are from the same wave of migrants who left Africa some 72,000 years ago.
In this second study, the migrants would be separated immediately after leaving the African continent via two different routes. Some of them populated southern Asia while the others went to Eurasia.
The third study, however, brings a small problem with this theory.
Based on genome already sequenced, enriched with 379 new European genomes, Luca Pagani from the Estonian Biocenter, and his colleagues note that at least 2% of the genome of the inhabitants of New Guinea reflects the ancestry of a distinct population who left Africa 120,000 years ago, earlier than those who populated Eurasia.
For Serena Tucci and Joshua Akey of the University of Washington with a comment also published in Nature, the results of Eske Willerslev, David Reich and their respective teams are compatible with the existence of a previous wave of migrations that led to the great migration as these early travelers genetically have contributed little to contemporary populations.