THE ORIGINS OF HIV

The human immunodeficiency virus (HIV) is the most dreaded killer of our race today. As of 2012, approximately 35.3 million people across the world have been infected by HIV, with new infections coming in at the rate of 2.3 million a year. It kills almost 2 million people a year on average, much more than war or rape or any other issue that we generally feel strongly about.
It’s perhaps surprising to note that the HIV is a rather recent discovery: it was clinically observed in the United States in 1981, in a Canadian flight attendant named Gaetan Dugas. The oldest case in the world can be dated back to 1959, from an adult male in the Democratic Republic of Congo. Though there has been some evidence that the first cases may have surfaced around the 1930s, one could say with reasonable certainty that HIV has been killing humans for only a few decades now. If left unchecked, it could claim us all.
The best accepted theory of the origin of the virus is that it is a descendant of the closely related Simian Immunodeficiency Virus (SIV), which infects monkeys. Certain viruses can pass from animals to humans in a process called zoonosis. HIV may have crossed this species barrier in this way, perhaps as a result of a human killing an infected chimpanzee and eating it for food, thus coming in contact with its blood.
In 1999, researchers confirmed that the SIV found in chimpanzees is virtually identical to HIV-1, an aggressive form of HIV.