from the LA times
HIV dates back to around 1900, study shows (by Mary Engel)
The study, led by evolutionary biologist Michael Worobey of the University of Arizona in Tucson, puts the date of origin at around 1900, which is 30 years earlier than previous analyses.
But figuring out when the virus jumped species and became established in humans has been difficult. The first cases in the U.S. were recognized in 1981, and the oldest evidence of the virus is a 1959 blood sample taken from a man who lived in what was then the Belgian Congo.