racial features: isolation or vanity?

At a time when the rest of the world was interbreeding with new migrants, the Chinese - and particularly the Japanese - remained a pure breed by virtue of isolation. Consequently, whatever features they started with remained with them whether or not these features were favorable to their  environment.

It takes thousands of years of natural selection for a feature to evolve into a noticeable change, but an evolutionary 'survival of the fittest' feature such as fair skin for an cold, sunless environment can be maintained in a sunny new environment simply by avoiding sunlight, and darkened by exposure to sunshine.

However, no sheltered existence out of the sun can turn a dark skin fair.

It is interesting to speculate about the extent to which our evolutionary physical differences are due to 'survival of the fittest' by natural selection or simple vanity. Possessing fair skin is a distinctive disadvantage in sunny climates, and yet in the matter of sexual preference - which determines whether or not your genes survive in future generations - vanity is not exactly immaterial.

The lack of body hair is also a distinctive disadvantage in cold climates, and while evidence exists that our ancestors used fire to remove excess body hair by singeing, it is not clear whether this was a pragmatic way to rid the body of lice or a simple matter of vanity - sexual preference favoring a smooth skin, differentiating human beings from their hairy early ancestors.

While sexual preference does, indeed, account for many of our physical differences, it is undoubtedly true that without the massive migration out of Africa that took place hundreds of thousands of years ago we would all look relatively similar.