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NSF PR 02-42 - May 23, 2002
First Primate Archaeological Dig Uncovers New Tool
A study of chimpanzees' use of hammers to open nuts
in western Africa may provide fresh clues to how tools
developed among human ancestors.
A paper published in the May 24 issue of the journal
Science documents the first archaeological
examination of a non-human primate workplace and establishes
new links between the use of tools by chimpanzees
and similar developments among human ancestors (hominids).
The research was supported in part by the National
Science Foundation (NSF). The research site is in
the Tai Forest, about 375 miles west of the capital
of the Ivory Coast, Abidjan.
A team from George Washington University (GWU) and
the Max Planck Institute for Evolutionary Anthropology
of Leipzig, Germany (which provided the primary funding
for the work) studied a site where chimpanzees had
carried in stone hammers from nearby areas to open
nuts on tree roots, which they used as anvils. The
researchers last fall, recovered 479 stone pieces,
chips of granite, laterite, feldspar and quartz broken
from the hammers.
"Some of the stone by-products of the chimpanzee nut
cracking are similar to what we see among the technologically
simplest Oldowan [hominid] sites in East Africa,"
said rainforest archaeologist Julio Mercader of GWU,
the lead author of the journal article, titled "Excavation
of a Chimpanzee Stone Tool Site in the African Rainforest."
Other scholars have documented similarities between
the hammers used by chimpanzees to open nuts and those
used by hominids, but no researchers have used the
techniques of human archaeology on non-human primate
sites, Mercader said.
The researchers have proved "archaeology to be a feasible
method of uncovering past chimpanzee sites and activity
areas in rainforest environments. This introduces
the possibility of tracing the development of at least
one aspect of ape culture through time," said Mercader,
a visiting assistant professor at GWU.
Melissa Panger, a GWU post-doctoral research fellow
who receives support through NSF's Integrative Graduate
education and Research Traineeship (IGERT) program,
said the discovery could help archaeologists establish
new dates for tool development. She and Christophe
Boesch of the Max Planck Institute for Evolutionary
Anthropology co-authored the paper with Mercader.
"We know that flaked stone tools were used 2.5 million
years ago, but stone tools may have been used by hominids
as much as 5 million years ago," Panger said. "If
we look for assemblages of stone pieces like those
we have found left behind by the chimpanzees, we can
infer that those assemblages may relate to tool use,
even if we don't have the tools themselves."
Mark Weiss, NSF program director for physical anthropology
said, "Understanding the activities of our early ancestors
involves a lot of detective work. Mercader, Panger
and Boesch's work is an ingenious approach to trying
to tease out more information from the archaeological
record-trying to flesh out the context of the earliest