In order to find out where HIV is coming from, several studies are being conducted. So far they thought it came from chimpanzees. In fact, the most common type of HIV virus in humans is very similar to a chimpanzee virus. However, new research also speaks of gorillas as possible sources. A much smaller HIV virus in humans resembles a gorilla virus. It is possible that these monkeys have passed from one species to another through the men who hunted and ate.