how did aids start

AIDS started from the transmission of the Human Immunodeficiency Virus (HIV) to humans. HIV is believed to have originally come from a similar virus called Simian Immunodeficiency Virus (SIV) found in chimpanzees in Central and West Africa. The virus crossed over to humans, most likely through exposure to infected blood during hunting or butchering of chimpanzees, sometime early in the 20th century—around 1920 in what is now Kinshasa, Democratic Republic of Congo. The earliest verified HIV infection in a human dates to a blood sample taken in 1959 from a man in Kinshasa. HIV then spread gradually among humans until it was recognized as a new disease in the early 1980s in the United States, where unusual illnesses appeared in young gay men. The infection and its disease syndrome were eventually named AIDS (Acquired Immune Deficiency Syndrome). The initial origin and spread were linked to social and environmental changes including urbanization, travel routes, and medical practices like unsterilized needles. In summary, AIDS started through the zoonotic transmission of a chimpanzee virus to humans in Africa in the early 1900s, followed by decades of unnoticed spread before being detected in the 1980s.