Very interesting article!
www.newyorker.com/reporting/2007/12/03/071203fa_fact_specter?currentPage=allThe article is somewhat long, so make your own cliff notes.
I found this very interesting:
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They focussed on chimpanzees, our closest relatives. Chimpanzees are easily infected by the AIDS virus, but it never makes them sick. That has remained one of the most frustrating mysteries of the epidemic. How did nearly identical genetic relatives become immune to a virus that attacks us with such vigor? The most dramatic difference between the chimp genome and ours is that chimps have roughly a hundred and thirty copies of a virus called Pan troglodytes endogenous retrovirus, which scientists refer to by the acronym PtERV (pronounced “pea-terv”). Gorillas have eighty copies. Humans have none.
“We can see that PtERV infected gorillas and chimps four million years ago,’’ Emerman told me. “But there was never any trace of its infecting humans.” It is possible that all infected humans died, but it is far more likely that we developed a way to repel the virus. Nobody knew why until Emerman, Malik, and Shari Kaiser, a graduate student in Emerman’s lab, presented evidence for a startling theory: the evolutionary process that protects us from PtERV may be the central reason we are vulnerable to H.I.V.
“We thought we must have a defense against this thing that they don’t have,’’ Malik told me, picking up the story the following day. Evolutionary biologists are not given to emotional outbursts—by definition, they take the long view. Malik is an engaging and voluble exception. When an antiviral protein excites him, he doesn’t hold back. “Where but in evolutionary history can you see a story like this, with PtERV and the chimps?’’ he asked, leaping up from his chair to begin sketching viral particles on a whiteboard. “It’s simply amazing.’’