Following the first steps out of Africa

The timing and pattern of the migration of early modern humans has been a source of much debate and research. Now, a new study uses genetic analysis to look for clues about the migration of the first modern humans who moved out of Africa more than 60,000 years ago. The research, published January 26 by Cell Press in the American Journal of Human Genetics, the official journal of the American Society of Human Genetics, provides intriguing insight into the earliest stages of human migration and suggests that modern humans settled in Arabia on their way from the Horn of Africa to the rest of the world. 

"A major unanswered question regarding the dispersal of modern humans around the world concerns the geographical site of the first steps out of Africa," explains senior study author, Dr. Luísa Pereira from the Institute of Molecular Pathology and Immunology of the University of Porto in Portugal (IPATIMUP). "One popular model predicts that the early stages of the dispersal took place across the Red Sea to southern Arabia, but direct genetic evidence has been thin on the ground." 

The work, led by Dr. Pereira at IPATMUP and Professor Martin Richards at the University of Leeds in the UK, in collaboration with colleagues from across Europe, Arabia, and North Africa, explored this question by analyzing three of the earliest non-African maternal lineages. These early branches are associated with the time period when modern humans first successfully moved out of Africa. The team compared complete mitochondrial DNA genomes from Arabia and the Near East with a database of hundreds more samples from Europe. Mitochondrial DNA traces the female line of descent and is useful for comparing the relatedness between different populations. 

The researchers found evidence for an ancient ancestry within Arabia. Professor Richards, who is now Professor of Archaeogenetics at the University of Huddersfield, concludes: "Taken together, our results suggest that Arabia was indeed the first staging-post in the spread of modern humans around the world." 

Source: Cell Press via EurekAlert! [January 26, 2012]

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