HIV origins

A group of international researchers announce that they have discovered the origin of the HIV virus in a community of wild chimpanzees in southern Cameroon. It is thought that Simian Immunodeficiency Virus was first passed on to people hunting these chimps in the 1920s. The researchers spent more than a decade digging in mounds of old chimpanzee faeces, genetically comparing the Simian Immunodeficiency Viruses they found to the earliest known HIV sample, taken from a man in the Congo in 1959.