The various races and ethnicities into which humans have evolved represent a grand experiment in which nature has tested out some of the variations i… - Nicholas Wade

The idea that human populations are genetically different from one another has been actively ignored by academics and policy makers for fear that such inquiry might promote racism. The argument offered here is that people the world over are highly similar as individuals but that societies differ widely because of evolutionary differences in social behavior. It would be better to take account of evolutionary differences than to continue to ignore them.

Over the last 50,000 years, modern humans have been subjected to enormous evolutionary pressures, in part from the consequences of their own social culture. They explored new ranges and climates and developed new social structures. Fast adaption, particularly to new social structures, was required as each population strove to exploit its own ecological niche and to avoid conquest by its neighbors. The genetic mechanism that made possible this rapid evolutionary change was the soft sweep, the reshaping of existing traits by quick minor adjustments in the sets of alleles that controlled them. But what began as a single experiment with the ancestral human population became a set of parallel experiments once the ancestral population had spread throughout the world. These independent evolutionary paths led inevitably to the different human populations or races that inhabit each continent.

Tribal behavior is more deeply ingrained than are mere cultural prescriptions. Its longevity and stability point strongly to a genetic basis. This is hardly surprising, given that tribes are the default human social institution. The inbuilt nature of tribalism explains why it took so many thousands of years for East Asians and later Europeans to break free of its deadening embrace.