Re: Article: Chimp tool use
- From: "Chapstick" <chapstick@xxxxxxxxx>
- Date: Mon, 26 Feb 2007 20:49:41 -0500
hi
this post also did not show up on Google Groups, so I am confused and not
sure if it went to the server correctly... thus... replying to myself...
--chap
"Chapstick" <chapstick@xxxxxxxxx> wrote in message
news:45dbb5c0$0$8934$4c368faf@xxxxxxxxxxxxxxxxx
http://www.sciencenews.org/articles/20070217/fob1.asp
Chimpanzee Stone Age: Finds in Africa rock prehistory of tools
Bruce Bower
Working along a riverbank in a West African rain forest, researchers have
uncovered remnants from a chimpanzee stone age that started at least 4,300
years ago. The finds constitute the only evidence yet detected of
prehistoric ape behavior.
Most of the more than 200 stone artifacts found at three sites in Taï
National Park, Ivory Coast, were used by prehistoric chimps to crack open
nuts, say archaeologist Julio Mercader of the University of Calgary in
Alberta and his colleagues. The animals placed nuts on the flat surface of
one rock and smashed the tough shells with another rock.
"I'd predict that this type of simple bashing technology goes back to a
common ancestor of chimps and humans around 6 million years ago," Mercader
says.
His team presents its findings in an upcoming Proceedings of the National
Academy of Sciences.
The researchers excavated a cluster of three sites in 2001 and 2003. Most
of the stone artifacts came from one location, known as Noulo. Radiocarbon
measurements of burned wood in the soil produced the age estimate for the
finds.
To see whether the artifacts could be distinguished as implements,
Mercader and two of his coauthors, both well-recognized specialists in
Stone Age tools, assessed a group of 90 stones, not knowing beforehand
their origins: the West African sites, a 5,000-year-old human occupation
in Canada, or a location in the Canadian Rockies where the stones had been
modified only by geological forces. In almost all cases, the three
examiners identified just the stones from the first two groups as being
intentionally modified.
Turning to the full set of specimens from the three West African sites,
the scientists concluded that most represent instances of one stone being
hammered forcefully against another. Those rocks weighed from 1 kilogram
to 9 kilograms (2.2 to 19.8 pounds).
The team also judged that people had apparently struck flakes off 28 of
the stones. People probably visited the frequently flooded riverbank sites
sporadically, Mercader posits.
Other clues suggest that chimps, rather than people, had used the unflaked
stones, For instance, large, heavy hammering stones at Noulo look like
those that chimps at a nearby site use to crack nuts (SN: 3/30/02, p. 195:
http://www.sciencenews.org/articles/20020330/fob2.asp). Both the old and
modern sets of artifacts contain small pits and hollow depressions
produced by bashing rocks together, as well as distinctive edge and corner
damage.
Finally, starch grains extracted from 31 stones at the West African sites
came predominantly from nuts typically eaten only by chimps, according to
Mercader's team. People living in that part of the rain forest mainly
subsist on tubers, plants, and fruits. The sites yielded none of the
pounding and grinding tools favored by foragers and farmers.
The new finds precede the emergence of farming villages in that part of
Africa. Mercader notes that it's possible that chimps imitated simple
stone-tool practices of human foragers. Still, he suspects that the
rock-bashing activity originated deep in prehistory.
Archaeologist Alison S. Brooks of George Washington University in
Washington, D.C., agrees: "There is no reason why future work should not
reveal evidence of even older chimpanzee sites." Starch grains last well
over 100,000 years, Brooks notes.
Although the new data make "a fairly solid case" for prehistoric nut
cracking by chimps, the animals probably invented this stone-tool
technique on their own rather than inheriting it from a common human-chimp
ancestor, remarks archaeologist John J. Shea of the State University of
New York at Stony Brook.
.
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