Clever orangutans invent nutcrackers from scratch

Animal behaviour

18 August 2021

Chimpanzees are not the only great apes to develop tools without tutoring.

Chimpanzees have long been thought to be the only non-human great apes to regularly smash nuts with stones or wooden hammers — one of the most complex forms of tool use observed in nature. Now, researchers have found that orangutans, too, can use hammers to crack open nuts, and they learn to do so without copying others.

Elisa Bandini at the University of Tübingen in Germany and her colleagues observed 12 zoo-dwelling orangutans (Pongo abelii and Pongo pygmaeus) that were given hard nuts and small wooden logs as potential hammers. None of the animals had previously broken nuts open with tools.

Some of the apes never tried the potential tools. But most wielded the logs as hammers to crack open the nuts, and three used a tree stump or another object as an anvil to stabilize the nuts.

Four animals started to use the tools without observing more experienced individuals, which suggests that orangutans can spontaneously learn to use objects as efficient nutcrackers, the researchers say.