HIV was first identified in 1983 by scientists. However, HIV-I was found to be surprisingly, an old disease with three separate subtypes M, N, and O. The best guess by scientists is that the condition is a precursor of the common subtype M virus that originated from Cameroon Chimpanzees to humans. This was even before 1930. A Virologist Dr. Bette Kroeber from Losse Alamos National Lab used samples of tissues infected by HIV tissues within a period of three decades. He calculated that the ancestral form of HIV began spreading in almost 80 years ago. The transfer of this virus from chimps to humans happened shortly after this period.