Captive gorillas actually are a cultured bunch.
Genetics or environment alone cannot explain variations in the behavior of different groups of the apes, a study has found.
Behavioral surveys of the roughly 370 gorillas in U.S. zoos showed 48 variations in how individual groups of the apes make signals, use tools and seek comfort, said Tara Stoinski of Zoo Atlanta and the Dian Fossey Gorilla Fund International.
"What became very obvious is there is a very distinct pattern of similarities and differences between groups," Stoinski said.
That suggests the gorillas pass along the different traits socially, not genetically, which is a hallmark of culture.
Results were presented Sunday at the annual meeting of the American Association for the Advancement of Science.
Researchers previously have found that other ape species, including chimpanzees and orangutans, show cultural differences as well in how they forage, use tools and court one another.
"These animals are smart enough to observe behaviors and imitate them," said Ingrid Porton, curator of primates at the Saint Louis Zoo.
That gorillas do the same and perhaps aren't the "slightly dumb cousins" of the ape family shouldn't be surprising, said Andrew Whiten, a professor of evolutionary and developmental psychology at the University of St. Andrews in Scotland.
"It is quite surprising only if you take that common notion that gorillas aren't as smart as the rest," said Whiten, a chimp expert.