A study in the journal Scientific Reports has described how orangutans were able to create hooks from wire to reach the handle of a basket, a surprising skill that even some human children find difficult.
In the paper, researchers led by the University of Vienna in Austria described how they gave orangutans a tube and a piece of wire, and tasked them with trying to reach a basket of rewards inside it.
In one experiment, they were given a vertical tube and a straight piece of wire. For this, they needed to bend a hook in the wire in order to reach the handle on the basket.
In a second test, they were given a wire already bent at right angles and a horizontal tube with a basket in it. To reach this one, they had to unbend the wire to push the basket out of the tube.
Amazingly, in the experiments – conducted at the Zoo Leipzig in Germany – the researchers found that several orangutans were able to bend or unbend the wire as necessary to reach the basket, with two solving the tasks within minutes.
"The orangutans mostly bent the hooks directly with their teeth and mouth while keeping the rest of the tool straight,” Isabelle Laumer from the University of Vienna said in a statement. “Thereafter they immediately inserted it in [the] correct orientation, hooked the handle and pulled the basket up."
The research is said to be the first time hook tool making has been seen in a non-human primate species. This is a task that children typically struggle to perform, with less than half at the age of seven able to solve the task. They significantly improve, however, when shown how to bend a hook.
But the orangutans did not require a demonstration. They were able to solve the task spontaneously, which came as a surprise to the researchers, who noted the animals were inventing a solution to the problem, rather than applying what they already knew.
"Finding this capacity in one of our closest relatives is astonishing,” Josep Call of the University of St Andrews, one of the study’s co-authors, said in the statement.
Call noted that hooks only date back 16,000 to 60,000 in humans. And while other animals like New Caledonian crows have been shown to use them somewhat regularly, such an ability had not been seen in apes before.