Chalk up modern humanity's rise and the extinction of Neandertals to a geographic accident. That's the implication of a new analysis of material from previously excavated Stone Age sites.
Homo sapiens evolved in Africa's resource-rich tropics. As a result, a division of labor arose beginning around 40,000 years ago that roughly corresponds to the arrangement found in most foraging societies today, say Steven L. Kuhn and Mary C. Stiner, both archaeologists at the University of Arizona in Tucson. Men in these societies hunt small and large game, while women and children gather tubers, berries, and other foods.
In contrast, Neandertals evolved in Europe and Asia, where large animals were the most abundant food source. Kuhn and Stiner suspect that individuals of both sexes and all ages collaborated in hunting. The high risks of killing the large beasts kept Neandertals' numbers low, the researchers propose.