First Step out of Africa

Genetic analysis of maternal lines of descent suggests that humans first moved to the Arabian peninsula before populating the world

The story of human origins is of interest to all, and it is only recently that genetic analysis has provided the means by which we can obtain details that had once seemed impossible to verify. The story so far suggests that humans first evolved in Africa and then moved out to populate the rest of the world. Various theories have been propounded about how humans did so, with some suggesting they moved from North Africa to Europe, while another more popularly held hypothesis suggests they did so by crossing the Red Sea into Arabia. New research backs this claim. In a paper published in American Journal of Human Genetics, scientists have analysed mitochondrial DNA to trace the maternal line of human descent to obtain their conclusions.

According to senior study author Luisa Pereira of University of Porto in Portugal, “A major unanswered question regarding the dispersal of modern humans around the world concerns the geographical site of the first steps out of Africa. 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 scientists analysed three maternal lines, termed N1, N2 and X, that branch directly from the first non-African maternal line termed N. They traced a common descent back some 60,000 years ago, roughly the time humans moved out of Africa. When the scientists compared samples from 85 southwest Asians with 300 European samples, they found that the data supports an ancestry for these lineages within the Arabian peninsula. The dispersal from Arabia seems to have taken place more than 50,000 years ago.

Martin Richards of the University of Leeds’ Faculty of Biological Sciences adds, “The timing and pattern of the migration of early modern humans has been a source of much debate and research. Our new results suggest that Arabia, rather than North Africa or the Near East, was the first staging-post in the spread of modern humans around the world.”

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Hartosh Singh Bal