Jun. 25, 2008, researchers reported that the human immunodeficiency virus (HIV-1) responsible for most of the AIDS cases in the world infected people approximately 100 years ago, more than 20 years earlier than previously believed.

Using comparative genetic sequencing, University of Arizona, Tucson, graduate student Joel Wertheim, adviser, Michael Worobey and colleagues reported that the a sooty mangabey caught its first SIV in 1808, and it jumped into humans 125 years later to become HIV-2.