Origin of AIDS Virus Pushed Back to 1908

An ABC News/AP article says that the AIDS virus is older than previously suspected. Since it is known to mutate rapidly, scientists have extrapolated the rate of mutation from a common ancestor to arrive at his new figure: it could have originated between 1884 and 1924, with a "more focused estimate" at 1908. A combination of hunting chimpanzees for their meat, the rise of cities in Africa, and the emergence of prostitution contributed to its spread, but it remained under the radar for many years.