Choose your poison: HIV or something else

Nonbiologists like me may read this Zimmer article with mouth firmly open ...

The Loom : Pleistocene Medicine for Battling HIV

...It turns out that human TRIM5-alpha does an excellent job of wiping out this ancestral virus. Its superior performance depends on a short bit of one of the virus's genes--a bit that shows signs of having experienced strong natural selection in our hominid ancestors. But evolving a strong resistance to PtERV1 meant giving up resistance to HIV. The viruses seem to force primates to make an evolutionary choice: defend against one or the other, but not both. In our ancestors, the scientists argue, TRIM5-alpha evolved into a powerful weapon against PtERV1--so powerful that we carry no trace of the virus in our genomes. But it left us with little protection against HIV

In order to test the modern reponse to the "ancestral virus" researchers had to resurrect it from relics buried in the human genome. The practice is kind of a cross between archeology and ... ummm ... omnipotence. We may not have jet packs or sentient AIs (as far as we know, yet), but our biology is well beyond what science fiction writers of the 1960s expected ...