Chimpanzees in Fongoli, Senegal, make and use weapons. On 22 occasions, they were seen making or using spears.
The chimps used the spears to hunt other primates that were hiding out of reach in hollows of trees or branches. They were stabbing, not probing, possibly with the intent to injure prey so that it could not flee. They often smelled or licked the points, and then stabbed again. One chimpanzee was seen drawing a bushbaby out of a hollow with a spear.
In most cases, the Fongoli chimpanzees carried out four or more steps to manufacture spears for hunting.
In all but one of the cases, chimps broke off a living branch to make their tool. They would then trim the side branches and leaves.
In a number of cases, chimps also trimmed the ends of the branch and stripped it of bark. Some chimps also sharpened the tip of the tool with their teeth.
Young or female chimps were seen to fashion spears more often than adult males. Dr. Preuetz said,
“It’s classic in primates that when there is a new innovation, particularly in terms of tool use, the younger generations pick it up very quickly. The last ones to pick up are adults, mainly the males.”
Jill Pruetz and Paco Bertolani are publishing their findings in the Feb. 22 issue of Current Biology. You can read a Eureka alert here.