Science Reports Some Chimps
Used Sophisticated Stone Tools

According to a report published in Science on 24 May, a group of US and German researchers have discovered that populations of chimpanzees in the rain forest of West Africa have used sophisticated stone tools to crack open palm, or panda, nuts. The panda nuts that the chimps cracked and ate are extremely tough, and can only be cracked open with tools. A single chimp may crack up to 100 nuts a day, the authors say, and it takes up to seven years for the chimps to learn how to crack them. The researchers compared the artifacts found at the nut-cracking site with some of the oldest known stone tools made by human ancestors, and found that the tools were fairly similar. Some of the simplest early human stone tool sites might therefore have been nut-cracking sites, the authors propose.

Photo by Christophe Boesch

"Thus, chimpanzees engage in cultural activities that leave behind a stone record that mimics some Oldowan occurrences and invite us to speculate whether some of the technologically simplest Oldowan sites could be interpreted as nutcracking sites," the authors wrote. "Or, more generally, if some subsets of artifacts from the more sophisticated Oldowan assemblages could be interpreted as evidence of hard-object feeding by early hominins."

The authors argued that only chimpanzees and not humans were responsible for creating the stone tools.

"The reasons for inferring chimpanzee agency at P100 are, first, the existence of an extensive behavioral record of chimpanzee nut cracking at the site that covers several years of observation," the authors wrote. "Second, no humans have been observed cracking Panda or palm nuts at Taý¨. Third, P100 is in a deep forest location removed from villages and trails."

24 May 2002