WASHINGTON, April 3 (UPI) -- U.S. researchers say they've discovered chimpanzees can learn whether people are generous solely by observing them interact with others.
Because chimpanzees have sophisticated social skills, the researchers said they wanted to learn whether chimps, like humans, can form accurate judgments about traits just by observing others, rather than directly interacting with them.
In their first experiments, the researchers allowed chimpanzees to observe unfamiliar humans consistently give (generous humans) or refuse to give (selfish humans) food to a familiar human.
In a subsequent experiment, chimpanzees observed unfamiliar humans consistently give or refuse food to other chimpanzees, rather than to humans.
When later allowed to directly interact with the generous or selfish humans, most of the chimpanzee observers preferred to interact with, and beg food from, the generous humans.
The George Washington University researchers concluded chimpanzees can learn "to infer stability in an individual's character or behavior over time through observation -- an inference that underlies the ability to make reputation judgments." The scientists said such a capacity "may have served as a catalyst to the evolution of various uniquely human traits, such as shared intentionality, language and reasoning."
The study appears in the journal Animal Cognition.
