Crafty Chimps Carefully Choose Materials For Their Tools [VIDEO]

You've likely seen the occasional video of chimpanzees poking around in ant hills with a stick or long reed, fishing for a tasty snack. Now researchers have determined that the tools used for this are actually carefully selected. "Any old stick" just won't do.

The technique, called "ant dipping," was initially believed to be a last resort for hungry chimps. However, recent field studies have revealed that ants are actually a staple in the chimpanzee diet - eaten year round regardless of the availability of other food sources.

A new study, recently published in the American Journal of Primatology, details how chimps will also carefully search for the right ant dipping tool, only settling for material from Alchornea hirtella, a spindly shrub whose straight shoots can scoop up mouthfuls of angry army ants without the risk of getting bitten.

"Ant dipping is a remarkable feat of problem-solving on the part of chimpanzees," author Kathelijne Koops from the University of Cambridge said in a recent release. "If they tried to gather ants from the ground with their hands, they would end up horribly bitten with very little to show for it. But by using a tool set, preying on these social insects may prove as nutritionally lucrative as hunting a small mammal - a solid chunk of protein."

Koops observed that chimps will resort to fashioning other ant dipping tools as well, but only after exhaustive searches for Alchornea hirtella shoots end without success.

So why such stubbornness about tool material? Koops argues that like any close-knit culture, chimp populations don't like breaking from tradition.

"Scientists have been working on ruling out simple environmental and genetic explanations for group differences in behaviors, such as tool use, and the evidence is pointing strongly towards it being cultural," Koops explained. "They probably learn tool use behaviors from their mother and others in the group when they are young."

This tool study is part of an ongoing larger project that attempts to discover more about how chimps teach and learn from one another.

[Credit: Cambridge University/Kathelijne Koops]