SIV, simian immunodeficiency virus, the monkey version of the virus that causes AIDS, is killing chimpanzees in the wild at a disturbingly high rate. Conservationists are concerned because chimps are already endangered.

Chimpanzees are the first primate besides man shown to get sick in significant numbers from a virus related to HIV. Chimps are also man's closest relative among primates.

Monkeys and apes -- except chimps -- seems to survive the virus because of some kind of evolutionary adaptation.

Hope for fighting AIDS in humans

The discovery of the disease killing chimps may help doctors come up with better treatments or a workable vaccine for humans.

"Chimps may be one evolutionary step ahead of us humans in managing the disease. And figuring out how to deal with their infection may ultimately help people infected with HIV," said virologist Beatrice Hahn of the University of Alabama.

It's long been presumed that the HIV jumped from chimps to humans when a human was bitten by a chimp, was cut while butchering one or ate an infected primate.

What can you do?

• Get involved in an endangered species organization.