Simian Immunodeficiency Virus, the non-lethal ape predecessor to HIV, might just be much older than current estimates, which peg it at only a few hundred years old. Research published in this week's Science shows the virus is at least 32,000 years old, and may even have been around for a million years. By analyzing simians that had been geographically isolated from mainland Africa for more than 10,000 years, they found significantly different versions of the virus, which they compared to already known variants in order to better understand the rate of mutation. Their evidence shows that the disease mutates much slower than previously thought, pushing back the origin to tens of thousands of years, and hinting that HIV might not mutate into a non-lethal form for a very long time.