First ancient African genome reveals complex human migrations - Africa is the birthplace of humankind but the climate here is imperfect for DNA preservation and this is the reason why all of the ancient genomes to be analyzed have been from Europe, Asia, and the Americas.

But things changed on Thursday, when a paper was published by researchers in Science documenting the genetic code of a man who died 4,500 years ago in what's now Ethiopia.

We know that after the great migration from Africa, some of the Eurasians who learned the art of agriculture returned to Africa.

That's what makes the newly sequenced man, named Mota, an interesting find. Mota lived in Africa before this second, backwards migration. Mota lacked the Eurasian DNA which is believed to have proliferated across the region about 1,500 years after his death.

"Roughly speaking, the wave of West Eurasian migration back into the Horn of Africa could have been as much as 30% of the population that already lived there - and that, to me, is mind-blowing. The question is: what got them moving all of a sudden?" Andrea Manica, senior author of the study from the University of Cambridge's Department of Zoology, said in a statement.

Manica and his colleagues reported that East Africans can attribute as much as 25 percent of their DNA to this Eurasian back flow.