http://www.newscientist.com/article/dn11165-did-prehistoric-chimps-use-stone-tools-too.html

(Can see pictures of the "tools" at the URL)

Did prehistoric chimps use stone tools too?
Bob Holmes


Over 4000 years ago, prehistoric chimpanzees were using stone tools to
smash nuts in the west African rainforest, a new study suggests.

The discovery represents the earliest known use of technology by chimps,
and could indicate we share a common tool-wielding ancestor with them.

When Julio Mercader of the University of Calgary in Canada, and
colleagues, excavated a 4300-year-old floodplain site in Tai National
Park, Ivory Coast, they found a variety of fashioned stone fragments. A
few are clearly of human origin, as they show systematic efforts to flake
rock to form edges. However, most of the fragments resulted from the kind
of cruder bashing action that chimps and humans use to crack nuts.

When Mercader and two colleagues reconstructed the original stone tools
from which the fragments came, they found that most were relatively large,
weighing an average of 710 grams. This is larger than tools used by Stone
Age humans, but a similar size to the hammer stones used by modern-day
chimps.

Nut lovers

Moreover, from the shape and size of the grains in plant residues lodged
in crevices in the stones, Mercader concludes that most came from nuts
rather than tubers or legumes. Many of these nut species, he says, are
eaten by modern chimps, but not ancient human hunter-gatherers. Putting
the two lines of evidence together, he reckons the site represents an
ancient feeding area where chimpanzees used stone tools


The simplest, most parsimonious explanation to having two lineages using
bashing technologies is that they both inherited that, rather than
inventing it separately,
Mercader says.

Not everyone agrees. There may have been prehistoric cultures we have yet
to discover that used heavier hammer stones and ate a wider range of nut,
notes Sally McBrearty, a paleaoanthropologist at the University of
Connecticut in Storrs, US. By piling inference upon inference as Mercader
does, she says,
you just get on shakier and shakier ground, because of the uncertainty
with each one of the steps
.

Journal reference: Proceedings of the National Academy of Sciences (DOI:
10.1073/pnas.0607909104)

Weblinks
Proceedings of the National Academy of Sciences
http://www.pnas.org/
Julio Mercader, University of Calgary
http://www.comcul.ucalgary.ca/mercader

Chimps Observed Making Their Own Weapons
http://www.washingtonpost.com/wp-dyn/content/article/2007/02/22/AR2007022201007.html?referrer=emailarticle

Chimps using spears?
http://newsvote.bbc.co.uk/mpapps/pagetools/print/news.bbc.co.uk/2/hi/science/nature/6387611.stm

Hunting chimps may change view of human evolution
http://news.yahoo.com/s/nm/20070222/sc_nm/chimps_hunting_dc

Hunting chimps may change view of human evolution
By Maggie Fox, Health and Science EditorThu Feb 22, 12:50 PM ET

Chimpanzees have been seen using spears to hunt bush babies, U.S.
researchers said on Thursday in a study that demonstrates a whole new
level of tool use and planning by our closest living relatives.

Perhaps even more intriguing, it was only the females who fashioned
and used the wooden spears, Jill Pruetz and Paco Bertolani of Iowa
State University reported.

Bertolani saw an adolescent female chimp use a spear to stab a bush
baby as it slept in a tree hollow, pull it out and eat it.

Pruetz and Bertolani, now at Cambridge University in Britain, had
been watching the Fongoli community of savanna-dwelling chimpanzees
in southeastern Senegal.

The chimps apparently had to invent new ways to gather food because
they live in an unusual area for their species, the researchers
report in the journal Current Biology.

"This is just an innovative way of having to make up for a pretty
harsh environment," Pruetz said in a telephone interview. The chimps
must come down from trees to gather food and rest in dry caves during
the hot season.

"It is similar to what we say about early hominids that lived maybe 6
million years ago and were basically the precursors to humans."

Chimpanzees are genetically the closest living relatives to human
beings, sharing more than 98 percent of our DNA. Scientists believe
the precursors to chimps and humans split off from a common ancestor
about 7 million years ago.

Chimps are known to use tools to crack open nuts and fish for
termites. Some birds use tools, as do other animals such as gorillas,
orangutans and even naked mole rats.

But the sophisticated use of a tool to hunt with had never been seen.


Pruetz thought it was a fluke when Bertolani saw the adolescent
female hunt and kill the bush baby, a tiny nocturnal primate.

But then she saw almost the same thing. "I saw the behavior over the
course of 19 days almost daily," she said.

PLANNING AND FORESIGHT

The chimps choose a branch, strip it of leaves and twigs, trim it
down to a stable size and then chew the ends to a point. Then they
use it to stab into holes where bush babies might be sleeping.

It is not a highly successful method of hunting. They only ever saw
one chimpanzee succeed in getting a bush baby once. The apes mostly
eat fruit, bark and legumes.

Part of the problem is this group of chimps is shy of humans, and the
females, who seem to do most of this type of hunting, are especially
wary. "I am willing to bet the females do it even more than we have
seen," she said.

Pruetz noted that male chimps never used the spears. She believes the
males use their greater strength and size to grab food and kill prey
more easily, so the females must come up with other methods.

"That to me was just as intriguing if not even more so," Pruetz said.

The spear-hunting occurred when the group was foraging together,
again unchimplike behavior that might produce more competition
between males and females, she said.

Maybe females invented weapons for hunting, Pruetz said.

"The observation that individuals hunting with tools include females
and immature chimpanzees suggests that we should rethink traditional
explanations for the evolution of such behavior in our own lineage,"
she concluded in her paper.

"The multiple steps taken by Fongoli chimpanzees in making tools to
dispatch mammalian prey involve the kind of foresight and
intellectual complexity that most likely typified early human
relatives."

hasn't this technique been observed in some other place - chimps pushing sticks into holes to spear ?grubs? - ?termites?

They seem to be distinguishing between sticking the stick into a termite mound and eating whatever comes out stuck to the stick, and actually planning/sharpening/using the stick to stab a mammal. At least, that's how I understand it. I suspect it's one of those distinctions that sounds a bit semantic to us (or should that be me?!), but for those people trying to drive back the die-hard behaviourists still trying to dismiss animal consciousness it's probably an important step forwards!