Donald G. McNeil Jr for The New York Times (September 16, 2010)
In a discovery that sheds new light on the history of AIDS, scientists have found evidence that the ancestor to the virus that causes the disease has been in monkeys and apes for at least 32,000 years — not just a few hundred years, as had been previously thought.
That means humans have presumably been exposed many times to SIV, the simian immunodeficiency virus, because people have been hunting monkeys for millenniums, risking infection every time they butcher one for food.
And that assumption in turn complicates a question that has bedeviled AIDS scientists for years: What happened in Africa in the early 20th century that let a mild monkey disease move into humans, mutate to become highly transmissible and then explode into one of history’s great killers, one that has claimed 25 million lives so far?
Among the theories different researchers have put forward are the growth of African cities and the proliferation of cheap syringes.
Confirming that the virus is very old also helps explain why it infects almost all African monkeys but does not sicken them. Over many generations, as any disease kills off vulnerable victims, the host adapts to it.
Island Biogeography Reveals the Deep History of SIV
Michael Worobey, Paul Telfer, Sandrine Souquière, Meredith Hunter, Clint A. Coleman, Michael J. Metzger, Patricia Reed, Maria Makuwa, Gail Hearn, Shaya Honarvar, Pierre Roques, Cristian Apetrei, Mirdad Kazanji and Preston A. Marx
Science 17 September 2010: Vol. 329. no. 5998, p. 1487 DOI: 10.1126/science.1193550
Link to Science abstract