Someplace in Africa—probably in East Africa near the Rift Valley—modern humans evolved about 200,000 years ago. The population rose and fell, and for one reason or another—perhaps climate changes, perhaps population pressure, perhaps wanderlust—small subsets of the people left to go elsewhere, creating their own groups—or rather our own groups, for these are, after all, our ancestors. Those groups spread in the same way, small subsets of the original groups leaving for greener pastures, sometimes returning and rejoining, sometimes leaving again. Africa has a huge range of environments—deserts, coastal regions, pampas, rivers, lakes, and mountains, and it is certain that some of these required human adaptations—behavioral, cultural and physical—to the demands of the various climates.
Eventually, we left Africa, somewhere between 50,000—100,000 years ago. Tishkoff and colleagues believe that the main exit path way was out of east Africa, in the Red Sea area.
Sources and Further Information
Tishkoff, Sarah A., et al. 2009 The Genetic Structure and History of Africans and African Americans. Science Express. 30 April 2009
Human Migration from Africa: Four Theories