As monkeys go, Sooty Mangabeys aren't cute.
Big-fanged, grey and hairy, they simply stare when threatened. Few zoos stock them. Some animal rights advocates can't even spell their name.
Nevertheless, the sooties are at the centre of a precedent-setting debate about whether researchers should be allowed to experiment on an endangered species. Scientists at the Yerkes National Primate Research Centre in Atlanta have nurtured a group of these primates for decades.
But after Yerkes started the colony, federal officials listed sooties as endangered.
The result: Yerkes has the world's largest collection of captive sooties, but with little hope of scientific benefit.
"We don't need them around just to look at them. We're not a zoo," said Thomas Gordon, Yerkes' associate director for scientific programmes.
Recently, Yerkes researchers proposed a novel solution: The primate centre will help conserve sooties in the wild in exchange for permission to do Aids-related research on them here. Such a trade-off has never before been permitted, said Timothy Van Norman, chief of the international permits branch at the US Fish & Wildlife Service.
"This is new territory," he said.
But animal rights activists are horrified.
"It's a deal with the devil," said Rachel Weiss, president of Laboratory Primate Advocacy Group, a Georgia-based animal rights organisation.
Yerkes - part of Emory University - is one of eight federally funded national primate research centres. Its scientific contributions include new understanding of monkey and chimp behavior and development of an experimental Aids vaccine.
In the 1990s, researchers learned sooties are natural carriers of a monkey-form of the Aids virus. Other types of monkeys get sick from the virus. Sooties don't. Researchers say if they can learn why sooties stay healthy, it may lead to new weapons against human HIV.
In July, the centre wrote Fish & Wildlife seeking the right to conduct research on the Yerkes sooties in exchange for preserving them in the wild.
The request is under review, Fish & Wildlife officials said. But animal rights advocates are uncomfortable.
"It's a tough call when you talk about conservation of a species versus protecting individuals. But we have to remember individuals comprise a species," Weiss said.