Is it true that HIV originally came from monkeys and apes?
There are two types of HIV (human immunodeficiency virus) that can cause AIDS, HIV-1 and HIV-2. HIV-1 causes most cases of AIDS in the U.S., only a few cases of HIV-2 have been found in the U.S. HIV-2 is mostly an infection of persons from West Africa. Scientists think that HIV-1 evolved from an immunodeficiency virus found in chimpanzees (simian immunodeficiency virus, or SIVcpz). Viruses that infect one species of animal, such as chimpanzees, generally don’t infect other species of animals, such as humans. Therefore, scientists do not know exactly how or why this particular virus ‘jumped’ from chimpanzees to people—also known as ‘cross-species transmission’. Scientists do believe, however, that SIVcpz evolved into HIV-1 many decades ago. DNA and genetic test results of HIV-1 indicate that it may have crossed into humans in the 1930s (Korber et al. 2000, Hahn et al. 2000). HIV-2 is believed to have come from a cross-species transmission of an SIV from a sooty mangabey monkey (SIVsm) (
