Aping the Stone Age
Chimp chasers join artifact extractors to probe the roots of stone tools
By Bruce Bower
For chimpanzees living in a forest surrounding the village of Bossou in Guinea, cracking nuts is a serious task with important steps. They are: First, lug large rocks to a spot near a nut-bearing tree, such as an oil palm. Next, gather the nuts and place them on the rocks. Then, obtain a smaller, graspable rock. Finally, smash the armored treats and let the shells fly. As clutches of apes pound away with devastating precision, these nut bashers create an unholy din akin to a human rock band.
In fact, these West African chimps rock out in a surprising way. In this corner of the jungle, chimps appear to think more carefully about implements and how to assemble them than many scientists had assumed. A team led by anthropologist Susana Carvalho set up a nut-cracking lab in the forest near Bossou by placing seven piles of nuts and several dozen stones of various sizes, shapes and types inside a clearing. Over five field seasons, 14 of 17 chimps that regularly visited the clearing consistently reused the same pairs of stones, the scientists report in a special October issue of Animal Cognition. Most chimps, Carvalho says, used the stones together as one tool, a nutcracker.