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[Carrie McLaren <temporary181 AT stayfreemagazine.org>]

Spear-wielding chimps snack on skewered bushbabies
http://www.newscientist.com/article/dn11234?DCMP=Matt_Sparkes&nsref=tools
17:00 22 February 2007

In a revelation that destroys yet another cherished notion of human 
uniqueness, wild chimpanzees have been seen hunting bushbabies with 
spears. It is the first time an animal has been seen using a tool to 
hunt a vertebrate.

Many chimpanzees trim twigs to use for ant-dipping and 
termite-fishing. But a population of savannah chimps (Pan troglodytes 
verus) living in the Fongoli area of south-east Senegal have been 
seen making spears from strong sticks that they sharpen with their 
teeth. The average spear length is 63 centimetres (25 inches), says 
Jill Pruetz at Iowa State University in Ames, US, who observed the 
behaviour.

And the method of procuring food with these tools is not simply 
extractive, as it is when harvesting insects. It is far more 
aggressive. They use the spears to hunt one of the cutest primates in 
Africa: bushbabies (Galago senegalensis).

Bushbabies are nocturnal and curl up in hollows in trees during the 
day. If disturbed during their slumbers - if their nest cavity is 
broken open, for example - they rapidly scamper away. It appears that 
the chimps have learnt a grizzly method of slowing them down.

Power grip

Chimps were observed thrusting their spears into hollow trunks and 
branches with enough force to injure anything inside the holes, 
Pruetz's research team says. The chimps used a "power grip" and made 
multiple downward stabs - much the same way as a human might wield a 
dagger.

Ten different chimps in the population were observed to perform this 
behaviour in 22 bouts. In one case the researchers saw a chimp remove 
a dead bushbaby and eat it.

The Fongoli chimps inhabit a mosaic savannah - patches of grass and 
woodland - where there are no red colobus monkeys. The absence of 
these monkeys, which are the favoured prey of several other chimp 
populations, may explain the Fongoli chimps' unique spear-hunting 
behaviour.

"Given the lack of opportunity, Fongoli chimps have come up with a 
way to get around the problem of how to get protein in their 
particular environment...using tools to hunt," says Pruetz.
Secret snacks

Intriguingly, the behaviour is mostly confined to females and 
immature chimps. Adults hunt and eat green monkeys, but males have 
priority over access to the meat. Pruetz suggests that Fongoli 
juveniles and females get around this by exploiting a niche that is 
relatively ignored by adult males - and spearing little bushbaby 
snacks for themselves.

"Immatures and females are innovative in solving the problem of 
feeding competition," she says.

Chimps regularly seem to be discovered doing things once thought 
unique to humans (see Stone Age chimps were handy with a hammer) - 
hunting vertebrates being the latest.

"Back to the drawing board again in terms of trying to define how 
humans are special," says Pruetz.