Savanna chimpanzees dig for food

Professor Toshisada Nishida wrote “chimpanzees are always new to me” (1) almost 15 years ago, but his statement still holds. Far from exhausting the breadth and depth of chimpanzee behavior, even when there are more long-term field studies than ever before, field primatologists studying Pan troglodytes continue to report new discoveries. Moreover, some of these findings, such as that of the spear-hunting chimpanzees of Fongoli, Senegal (2), are so unexpected that they make popular as well as scientific news. Likely to make similar waves is the report by Hernandez-Aguilar et al. (3) in this issue of PNAS that wild chimpanzees use digging tools to harvest plant underground storage organs.

One reason for the prominence given to these new data is their origin: another hot, dry, and open ecotype, in this case the savanna woodland (“miombo”) of the vast Ugalla region of western Tanzania (Fig. 1). (This little studied, unprotected area is adjacent to, but separated by mountains from, the famous Mahale Mountains National Park on the eastern shore of Lake Tanganyika.) As with other recent reports, including the bush baby-skewering apes cited above, it is these wide-ranging, open-country apes who are extending the behavioral repertoire of humankind's closest living relations. Recent examples are the cave-using chimpanzees of Fongoli (4), the anvil-using chimpanzees of Assirik, Senegal (5), and the well-digging chimpanzees of Semliki, Uganda (6). All of these populations, …

*E-mail: wcm21{at}cam.ac.uk