While most people tend to think in terms of human populations spreading out to the Mid East, Europe and Asia some 60,000-70,000 years ago, a new study led by Andrea Manica of the University of Cambridge’s Department of Zoology has found that some groups from Ethiopia, Somalia, Djibouti and Eritrea can trace more than 30% of their DNA to a “reverse” migration of people from Eurasia that is believed to have occurred sometime after humans began developing an agricultural society. Among the crops they most likely brought with them were wheat, barley and lentils.In addition, Manica’s study found that 5% of the genome found in Southern and Far Western Africa is of Eurasian in origin.
“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, stated Manica, who now would like to find out what motivated them to come back to the continent from the Middle East and Turkey about 3,000 years ago.
The dating of the return is based on documentation of the genetic code of a man who died 4,500 years ago in what is now present- day Ethiopia.The fact that the man (whom they have dubbed Mota after the region where he was found) lacked the Eurasian DNA that seems to indicate that the reverse spread across the region came about 1,500 years after his death.
Up until now, ancient DNA has been hard to come by in Africa due to the climate there, which unlike Europe, tends to cause it to decay over time. However, Mota’s body was found face-down in a cave located in the highlands of southern Ethiopia some 8,100 feet above sea level, where the cool, dry conditions preserved it and allowed the scientists to extract a sample from the petrous bone at the base of his skull. The resulting sequence is the first nuclear genome from an ancient African, according to a report published the October 8th issue of the journal Science.
While Mota’s genome was a close match to the Ari people of southern Ethiopia they also found that the Ari ancestry held evidence that they not only shared DNA with modern-day Sardinians, who are known to be the closest living relatives to the earliest farmers, as well as the LBK culture, early farmers who lived in Germany about 7,000 years ago.
