from the LA times
HIV dates back to around 1900, study shows (by Mary Engel)
A genetic analysis of a biopsy sample recently discovered in the Democratic Republic of the Congo has led researchers to conclude that the virus that causes AIDS has existed in human populations for more than a century, according to a study released Wednesday.
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.
HIV-1, the most common form of the virus, is known to have originated in chimpanzees because of close genetic similarities to a simian virus. It now infects an estimated 33 million people worldwide.
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.
Read the rest here. Or here is the abstract of the original article in Nature.