The fact that human evolution has been recent, copious and regional is not widely recognized, even though it has now been reported by many articles i… - Nicholas Wade

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.

There are two important factors to consider in the emergence of social change. One is that a society develops through changes in its institutions, which are blends of culture and genetically shaped social behavior. The other is that the genes and culture interact. This may seem paradoxical to anyone who considers genes and culture to be entirely separate realms. But it is scarcely surprising from an evolutionary perspective, given that the genome is designed to respond to the environment, and a major component of the human environment is society and its cultural practices.

The classification of humans into five continental based races is perfectly reasonable and is supported by genome clustering studies. In addition, classification into the three major races of African, East Asian and European is supported by the physical anthropology of human skull types and dentition.