Tool use is well documented among chimpanzees, but new research has found that when it comes to smashing nuts with rocks these animals need a little help from their friends. Whether problem-solving through the medium of smash boulder is a learned or innate behavior has been a debated topic, but these new findings would support the idea that this complex behavior is learned from others.
Published in the journal Nature Human Behavior, the new study used field experiments to determine what’s needed for a chimp to learn the behavior of using a rock as a tool to crack nuts. The primatologists on the study tuned to chimps in Seringbara in the Nimba Mountains, Guinea, to test whether chimpanzee nut-cracking could spark up under the right conditions.
The recipe for a cracking nut party is as follows: palm nuts and stones, palm fruit bunches, cracked palm nuts, and Coula nuts and stones. The theory was that if given the right tools and treats, the innate behavior of using rocks as tools to break down the tough but tasty food items would emerge.
Sure enough, the wild chimpanzees rocked up to the nut parties, but no nut-cracking occurred. Not ones to rush innovation, the researchers gave a total of 35 chimps over a year to familiarize themselves with the experimental items.
Of the animals studied, 11 parties closely investigated the nut-rock buffet, and showed themselves to be more eager to explore when arriving en masse. However, only one female chimpanzee was ever seen eating the palm fruit, and nobody got as far as trying to crack or eat the oil palm and Coula nuts.
It’s therefore the team’s conclusion that for the chimps of Seringbara, at least, nut-cracking tool use requires social learning to be adopted, not just the right ecological conditions. This shows that the cultural behavior mirrors some human ones in that it has to be passed on socially rather than spontaneously innovated.
“Our findings suggest that chimpanzees acquire cultural behaviors more like humans and do not simply invent a complex tool use behavior like nut-cracking on their own,” lead author Kathelijne Koops said in a statement.
“Our findings on wild chimpanzees, our closest living relatives, help to shed light on what it is (and isn’t!) that makes human culture unique. Specifically, they suggest greater continuity between chimpanzee and human cultural evolution than is normally assumed and that the human capacity for cumulative culture may have a shared evolutionary origin with chimpanzees.”
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