[CobaltBlue]

Most people still don't have the virus, but if its ancestor had been in Europeans long ago, all people of European descent would have some form of it.

Like we all have some form of smallpox?

[VadeRetro]

I wonder if an analysis of the simian virus family would point to a recent intro as does the human one. The reverse of your funny coincidence is that dusky mangabys got one strain of human viruses from humans at almost the same time chimps got another strain of human virus. But what if there are equally unrelated strains in, say, gorillas that have no human counterpart? (Don't know if it's true, just wondering.)

Or are you saying that humans did get the thing from primates, only some time in the far past? Why then don't Africans show the immunity?