Meditate on this thoughtfully for a day or two: The merging of already long-diverged human varieties is the opposite of evolution, and, if sufficiently widespread, can cancel out hundreds of thousands of years of divergent evolution in a single generation. Had it happened on a large scale in the past, as it is happening now, there would have been no Siddhartha Gautama, no Socrates, no Nietzsche -- no Phidias, no Titian, no John William Waterhouse -- no Parthenon, no transistor, no Saturn V rocket -- since humanity would still be barely above the level of Homo erectus.