Harvard Medical School researchers have identified a gene in Asian macaque monkeys may have evolved as protection against a group of viruses that includes HIV, suggesting that the current AIDS epidemic is not unique to humans and that similar epidemics may have affected our primate ancestors.
The gene identified is a combination gene which is a hybrid of two existing proteins TRIM5 and CypA. In 2004 another similar combination gene was found in South American owl monkeys and it is believed the two combination genes developed separately in both species. This is called convergent evolution and it is thought to confer an evolutionary advantage, possibly having been important in preventing infection by prehistoric viruses related to modern day HIV.
Public Library of Science February 28, 2008