ABSTRACT - Joint international study tracing origin of AIDS virus reports that simian precursor was created in chimpanzees that ate two kinds of monkeys with different but related viruses; photos of spot-nosed guenon, red-capped mangabey and chimpanzee; graph explaining genetic transfer; same team concluded four years ago that humans probably got AIDS virus from butchering chimpanzees for food; co-author Beatrice Hahn explains (M) Four years after arguing that humans probably got the AIDS virus from butchering chimpanzees for food, the same researchers say they have traced the origin back one step further: to the monkeys that the chimpanzees ate.

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