We have already see them using tools of different ways all over African continent – cutting nuts with rocks to take out their meat, taking out the leaves of a branch to get ants, drinking water through a leaf or even turning the branches of a tree into lances, which they use as hunting guns. But we had never seen them cutting the food into small pieces and this is what a research team reported at magazine “Primates”. 

The chimpanzees who promoted this news are the ones who live at Nimba Mounts, in the borderline of Liberia, Ivory Coast and Guine-Conacri, six kilometers far away of an investigative station managed by Japan, in the Guine village of Bossou. For more than 30 years the chimpanzee community who live in the near round forest has been studied.

Kathelijne Koops, PhD student of William McGrew, of Evolution Studies Center of Cambridge University, at United Kingdom, investigates the use of tools by chimpanzees in the Forest of Nimba Mounts when they look for food.

“All over Africa, chimpanzees change a lot in the type of tool they use to get food. Some groups use rocks as hammers and anvils to cut nuts, while others use branches to catch termites”, said Kathelijne Koops to BBC online. “For instance, to cut the nuts, the chimpanzees of Bossou use mobile hammers and anvils and, sometimes, use a kind of layer in the anvil, to turn it more efficient.”

Now, Kathelijne Koops, William McGrew and Tetsuro Matsuzawa – director of Bossou station, managed by Primates Investigation Institute of Kyoto University, in Japan – report the discovery of a new use of tools: the chimpanzees also use rock and wood knives to cut the fruits of the African plant Treculia africana, instead of hitting the fruit against a rock to open it.

At Nimba Mounts, those fruits reach the size of a volley ball and weight more than 8,5 kilos, write the scientists in the article. “They are extremely tough and solid, but they do not have a heavy skin. The fact that they are big and have a thick and spherical structure can make it harder for them to bite the fruit.”               

Then, they put them over firm rocks, which work as anvils, and cut them with the knives in pieces they are able to put into their mouths.

Público Newspaper – Portugal – by Teresa Firmino