In this week’s installment of Medical Discovery News, UTMB’s Norbert Herzog and David Niesel report that scientists now believe all simian immunodeficiency virus strains across Africa diverged from a common ancestor between 32 thousand and 78 thousand years ago. It’s likely that SIV infected humans many times in history and one or more of these viruses turned into HIV. But before the colonization of Africa, infected hunters most likely died before the virus could spread.