HIV, which causes Aids, emerged in humans in the 20th Century, but scientists have long known that similar viruses in monkeys and apes have existed for much longer.A genetic study shows HIV-like viruses arose in African monkeys and apes 5 million to 12 million years ago.
The research may one day lead to a better understanding of HIV and Aids. HIV affects 34 million people worldwide. The disease emerged during the 20th century after a HIV-like virus jumped from chimps to humans.
Scientists have long known that similar viruses, known as lentiviruses, are widespread in African primates. Past genetic research has suggested these "cousins" of HIV arose tens of thousands of years ago, but some experts have suspected this is an underestimate.