Great apes enjoy monkeying about … just like humans

Azibo the juvenile chimpanzee likes to body slam the adult chimps and then run away. If this seems oddly familiar to human parents, it should not be a surprise.

Baby chimpanzees have been found to share some traits with their human counterparts. Picture: Justin Lloyd.

Azibo the juvenile chimpanzee likes to body slam the adult chimpanzees and then run away. If they do not respond, he keeps going until they do.

Denny the gorilla has similar interests, but prefers to keep it simple and ambush his mother from behind while hitting her.

Aisha the orangutan finds – perhaps in a reflection of the naturally hirsute attributes of her species – that pulling the hair of the adults is an excellent way to pass the time.

If any of this behaviour seems oddly familiar to human parents, then that should not be a surprise. All three juveniles were part of research that shows humans are far from the only great ape to engage in “playful teasing”.

And, says Isabelle Laumer of the Max Planck Institute of Animal Behaviour, in Konstanz, Germany, while it might be tedious to be on the receiving end of it, it demonstrates clear intelligence.

“Joking draws on complex cognitive abilities. In order to joke you need to understand social norms. You need a theory of mind. Playful teasing, which we can see in children of eight months, may be a precursor to this,” she said.

When a human child offers and withdraws an object or blocks someone’s path, it requires understanding of and subversion of another’s intentions. Deliberately riling someone is only possible if you can put yourself in their mind. The same is true with apes.

The research, published in Proceedings of the Royal Society B, is the first to look systematically at teasing behaviour in other apes – by studying hours of film of chimpanzees, bonobos, gorillas and orangutans in two zoos.

Teasing was defined by the researchers as behaviour that was difficult to ignore, often one-sided and – to paraphrase – extremely irksome. They were, they found, remarkably uniform between the species.

“What we found in general is they teased in similar ways,” Ms Laumer said. “It was poking, hitting, hindering movement. For orangutans, hair-pulling was more common. Probably it’s more fun to pull on long hair.”

As well as poking, hair-pulling and hitting, Ms Laumer and her colleagues included tickling, swinging and, to give one more specific example, battering an adult in the face with a rope.

One feature of the behaviour – also, perhaps, familiar to human parents – is that the adults would often try to pretend it was not happening.

“We found that they mostly ignored the behaviour, as a first strategy,” Ms Laumer said. Usually, as with humans, the adult apes found this did not work. “The teaser would look at the target. If the target was not reacting they did something else. Maybe a hair-pull, a poke, jumping, or pulling on the leg.”

Eventually, the juvenile apes got attention. What they almost never got, though, was aggression. During a total of 75 pokes, 53 hits, 30 body slams, 50 occasions of pulling/swinging on an adult and 13 thefts, only one time in 20 did the adult get angry.

Ms Laumer said it was not completely clear why the young did this. There are, though, established theories that might explain it. “At least for human children, through playful teasing, social boundaries can be tested.”

This shared behaviour with our closest cousins adds weight to the idea that it fulfils some purpose. It suggests that we have a common ancestor that also engaged in teasing. Or, in more colloquial language, the findings show that for at least 13 million years, primate babies have been really annoying.

The Times