There have been significant and substantial changes in skeletal structure over the last ten thousand years. One can reasonably define the white race in such a way that it is only ten thousand years old, that everyone before then was non white, not that we know what skin color they were.

Modern races or rather population groups though they have some deep roots due to archaic admixture are probably mostly rather young. For example the West African type seems to have only arisen with tropical agriculture a few thousand years ago, and has expanded its range in basically historical times (one of the reasons that until quite recently people liked to think of the Khosians as something of urhumans).