Almost 1,000 monkeys run wild on Cayo Santiago, an uninhabited, 37-acre island just off Puerto Rico's coast that supplies primates for behavioral research at the site as well as AIDS experiments in top U.S. laboratories.
These rhesus macaques have been the exclusive inhabitants of "Monkey Island" for 70 years. In 1938, scientists brought 409 of the monkeys here from India for use in research, and the population grew steadily.
Since rhesus macaques are vital for the testing of AIDS vaccines, researchers cull some of the population each year for use in laboratory experiments. They are provided with food and water, and are tattooed for identification, but otherwise live freely, as they would in the wild.
The monkeys are relatively tame, and and are accustomed to being observed by teams of primatologists who boat in from the big island during the day to perform behavioral experiments. But they are wild animals, not always friendly, and like many wild monkey populations are infected with a strain of herpes that can be deadly to humans if scratches or bites are left untreated.
