In a study to be published in the November issue of PLOS Biology scientist announce they have discovered gorillas using tools. It has been known for quite some time that chimps use tools but no one had ever witnessed gorillas using tools in the wild. What makes this study so important, though, isn’t the fact that gorillas were using tools. It’s how they used them that made the study so important.
From New Scientist:
They saw a female gorilla nicknamed Leah attempting to wade through a pool of water created by elephants. After quickly sinking waist deep, she got out of the water and picked up a metre-long stick, says Breuer. She then re-entered the water and repeatedly prodded the stick ahead of her as if to test for depth. She advanced about 10 metres before returning to her wailing infant on the edge of the pool.
“It was exactly how you or I might have tested the depth of the water,” Breuer told New Scientist, by satellite phone from a forest clearing in Nouabalé-Ndoki.
A second example was also captured on film, when Efi, a gorilla from another group, used a stick to lean on for support while she foraged for food with her free hand. She then used the same stick as a bridge to help her cross a patch of swampy ground, says Breuer.
“Both cases seem related to the problems of locomotion in this swampy forest clearing,” says Breuer. This suggests that the tool use stems from an ecological need.
“Most great ape tool use is based around the retrieval of food,” notes Gillian Sebestyen-Forrester who studies gorilla communication at the University of Sussex, UK. But the “incredibly intuitive” behaviour of using a stick to test water depth is something quite different, she says.
“The gorillas have understood in some capacity that they can extend their sensory experience and find out more about their environment by physically extending their bodies with an inanimate object,” she says. “This suggests that the gorilla is capable of some mental calculation and abstract thought.“
Footprints of gorillas were found on branches in nearby clearings suggesting their use as bridges could be widespread, says Breuer.
From National Geographic News:
“The most fascinating thing about this observation is the similarity [to humans] with which the gorillas solve the problems in this particular habitat,” he said. “If you or me want to cross a swamp, we use the same solutions as gorillas.”
Like humans, the gorillas in the swampy clearing jump from one dry patch to another, walk over branches, swing from trees, and—as the observations and photographs now show—use tools.
Totally cool research!
Added Later: Abnormal Interests has a post on the gorillas as well.