...because viruses evolve faster than humans.
I wanted a good "this is never a good start for a topic" title, and then flip it around to be the opposite.
It also becomes more acceptable, take that as you will...
europeans have the most neanderthal. se asians & oceanians have beaucoup denisovan admixture as well.
https://www.sciencedaily.com/releases/2016/03/160328133514.htm
africans have more somatic genetic diversity, but not the exotic archaic admixtures as do euros/asians.
the notion that humanity, all humans, behave as a virus has real ecological validity to it, i think. at the rate we're going, any way.