You're at a party when you hear someone shout, "I'm going to kill you!" If you've just had a pleasant conversation with that person, it's safe to assume he's yelling at someone else. A new study suggests that baboons employ similar reasoning when deciding whether another's threatening grunt is intended for them. This is the first time the ability to intuit another's intentions through vocalizations has been confirmed in nonhumans, say the researchers.
Baboons live in social groups of up to 75 individuals and frequently interact using touches, facial expressions, and grunts. The animals have distinctive voices, and a listening baboon can tell who is talking, but scientists didn't know whether a baboon could tell whether it was the one being spoken to.
A research team, led by behavioral ecologist Anne Engh of the University of Pennsylvania in Philadelphia, sought an answer in a group of 70 baboons living at a game reserve in Botswana. The researchers played a recording of a dominant female's threatening grunt to a lesser-ranking female who had recently either fought or groomed with the dominant female. Subordinate females who had just brawled with their superior looked up toward the speaker faster and were more likely to leave the area than the groomers were, the researchers report online 18 January in Animal Behaviour.
Engh says that correctly identifying the target of a grunt is a seemingly simple task, but in fact it involves a complex mix of inferences about the motives and intentions of other baboons in the community. "It seems so obvious because we're humans and are doing this all the time," she says.
The study "adds a piece of understanding to our picture of [baboons'] cognitive world," says behavioral ecologist Susan Alberts of Duke University in Durham, North Carolina. Joan Silk, a behavioral ecologist at the University of California, Los Angeles, adds that the research provides good evidence that baboons can link past events to the future behavior of another individual. "This comes closer to what we think of as a 'human' ability," she says.