WASHINGTON, D.C. AND LEIPZIG, GERMANY - Chimpanzees in a remote West African rainforest use stones and branches as hammers to crack open different types of nuts when foraging. While the nuts they crack are available throughout tropical Africa, this nut-cracking behavior has been documented only among chimpanzees from western Cte d'Ivoire, Liberia and southern Guinea-Conakry.
How old is this behavior? Have nut-cracking techniques changed over time? To answer these questions, a unique collaboration of scientists - Christophe Boesch, an expert in chimpanzee behavior of the Max Planck Institute for Evolutionary Anthropology in Germany, Julio Mercader, a specialist in rainforest archaeology in The George Washington University Department of Anthropology, and Melissa Panger, who studies primate tool use at GW - launched an archaeological excavation of a chimpanzee nut-cracking site in Cte d'Ivoire's Tai National Park in September 2001.
Using archaeological methods on a non-human species for the first time, the excavations revealed new facets and confirmed others of chimpanzee tool behavior. Chimpanzees at the site known as "Panda 100," for example, collect rocks from various sources across the landscape and bring them to nut-cracking sites.
The repeated occupation of the same site over many seasons allowed for the cracked nut shells and stone pieces that break off of the hammers to build up. The unearthed materials include more than 479 stone pieces that may have flaked off when smashed on tree roots the chimpanzees used as anvils.
In addition to the possibility of tracing ape culture back in time, the scientists also believe the research will open up new ways of interpreting some early hominid, or human, sites.
"Some of the stone by-products of chimpanzee nut-cracking are similar to what we see left behind by some of our early ancestors in East Africa during a period called the 'Oldowan,'" said Mercader, the lead author of th
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Contact: Bob Ludwig
bludwig@gwu.edu
202-994-3566
George Washington University
23-May-2002