"This is a truly astounding discovery," said Thomas Breuer of the Wildlife Conservation Society. "Tool usage in wild apes provides us with valuable insights into the evolution of our own species and the abilities of other species. Seeing it for the first time in gorillas is important on many different levels."
According to the study published in the open access journal PLoS Biology, on two separate occasions in the northern rain forests of the Republic of Congo, researchers observed and photographed individual western gorillas using sticks as tools. The observations were made in Mbeli Bai--a swampy clearing located in Nouabal-Ndoki National Park where monitoring has been ongoing since February 1995. The first instance occurred when a female gorilla nicknamed Leah by scientists attempted to wade through a pool of water created by elephants, but found herself waist deep after only a few steps. Climbing out of the pool, Leah then retrieved a straight branch from a nearby dead tree and used it to test the depth of the water. Keeping her upper body above water, she moved some 10 meters out into the pool before returning to shore and her wailing infant.
Then another female gorilla named Efi used a detached trunk to support herself with one hand while digging for herbs with the other. As she moved from location to location, she used the stick for one last job, a bridge over a muddy patch of ground.