The groundbreaking theory that Homo sapiens originated in Africa before slowly spreading across the world has been powerfully backed by new research into variations in the male sex chromosome. This suggested that modern man first appeared on the scene in Eastern Africa about 150,000 years ago, leaving between 35,000 and 89,000 years ago on a relentless push in which the species eventually conquered the planet. A major research effort from scientists in eight nations, published Monday in November's issue of the U.S. journal Nature Genetics, has now validated the theory, and in so doing has devised a potent tool to probe the very earliest origins of mankind. The team drew up a genetic family tree of mankind thanks to small variations in the genes of 1,062 men in communities around the world.
Women carry two X chromosomes.
Variations in these markers corresponded astonishingly to the geographical location of where the men live. In other words, the markers reflected the waves of human migration that unfolded across the world over tens of thousands of years. Each ripple caused a tiny disturbance in the male gene pool as the species intermingled and the Y chromosome adapted to the process of natural selection. Samples were taken from men in 22 geographical areas in countries that included Pakistan, India, Cambodia, Laos, Australia, New Guinea, the U.S., Mali, Sudan, Ethiopia and Japan. Their allele mutations were then assembled into 10 types, called haplogroups.