The Evolution of Hunters

I found this news really astonishing. Seeming plausible, the discovery provides a most sound evidence to argue how we homo sapiens started our evolution. Below is excerpted from news of Science. The original report is on Current Biology whose full text I have no access to.

Spear-Wielding Chimps Seen Hunting Bush Babies

Ann Gibbons

The right to bear arms has long been considered a distinctly human privilege. But apparently the Second Amendment to the U.S. Constitution applies to chimpanzees too, at least while they're out hunting small game.

Researchers in Senegal recently spotted wild chimpanzees biting the tips of sticks, which they then used like spears to jab small primates called bush babies. Anthropologist Jill Pruetz of Iowa State University in Ames was astonished when her project manager saw a chimp thrust a sharpened stick into a hole in a tree and pull out a limp bush baby to eat, according to a report in the 6 March issue of Current Biology.

Bush baby, beware. Senegal chimps like this one attacked bush babies with sharpened sticks (inset). CREDIT: P. BERTOLANI/CAMBRIDGE (PHOTO AND INSET)

"This is stunning," says primatologist Craig Stanford of the University of Southern California in Los Angeles. It's the first time a nonhuman primate has been known to make a lethal weapon for hunting other animals, he says. "This is no anecdote, as they have 22 cases," adds primatologist William McGrew of Cambridge University in the U.K. "Once again, chimpanzees exceed our imaginations."

Anthropologists have known for some time that chimpanzees are adept at making and using stick and stone tools, for example to probe termite mounds or crack nuts. And researchers have seen gangs of male chimps kill monkeys by beating and biting. But they thought only humans used tools to hunt.

Pruetz's team, working at the Fongoli research site in the wooded savanna of Senegal, observed chimps breaking off green branches and in four cases using their incisors to sharpen the points. The chimps, which typically weigh 26 to 60 kilograms, were hunting nocturnal bush babies, 100- to 300-gram primates that hide by day in holes in trees. In all, Pruetz and Paco Bertolani, a graduate student at Cambridge University, documented 10 different chimps thrusting the tools into holes in 22 instances. "This is habitual," says Pruetz, whose team logged 2500 hours of observations.

Other researchers were impressed by the observations, although some noted that the researchers saw only one bush baby actually killed. "Could they have been rooting around for something else?" asks primate behavior ecologist John Mitani of the University of Michigan, Ann Arbor.

Pruetz says the chimps' intent was clear: They jabbed the sticks in the holes with enough force to injure prey and far more vigorously than when probing for termites. And bush baby remains were common in chimp feces, indicating they were regular fare.

In another surprising twist, most hunters were females. "It's a double whammy," says Pruetz. "It doesn't fit the old paradigm of Man the Hunter." Make that Chimp the Hunter.