AIDS (Acquired Immunodeficiency Syndrome) came about as a consequence of the Human Immunodeficiency Virus (HIV) crossing over from non-human primates to humans. The most common form of HIV, known as HIV-1, originated from a virus found in chimpanzees in West-Central Africa. This virus, called Simian Immunodeficiency Virus (SIV), is closely related to HIV and likely transmitted to humans when hunters were exposed to infected chimpanzee blood, probably between 1890 and 1920 in what is now the Democratic Republic of Congo, near Kinshasa. The earliest known case of HIV in a human is from a blood sample taken in 1959 in Kinshasa. HIV spread silently for decades before AIDS was recognized as a disease in the early 1980s when unusual clusters of illnesses related to immune deficiency were reported, particularly among gay men in the United States.
The origins of AIDS are linked to social changes caused by colonialism in Africa, including urbanization, increased sexual activity, and the use of unsterilized needles, which helped the virus spread within and beyond Africa. The recognition of AIDS as a distinct syndrome occurred in 1981, and the virus causing it (HIV) was identified shortly thereafter in 1983.
In summary, AIDS came about due to a zoonotic transmission of SIV from chimpanzees to humans, likely through hunting practices, followed by mutations and social factors that allowed the virus to spread widely in human populations over the 20th century.
