Great apes have a penchant for joking and clowning, a new study shows – a finding that sheds new light on the origins of human humor.
All species of great apes occasionally tease, mess and torment their peers and older relatives – and then stand back to watch the results, according to findings published Tuesday in Royal Society B.
The paper suggests that humor is a widespread feature of the simian family tree, stretching the origins of ‘playful teasing’ in humans back to at least 13 million years ago, when the great apes began to split.
It also offers a glimpse into a tantalizing new line of research that has emerged in the 21st century: the idea that play and non-immediately practical behavior may play a larger role in animal life than was commonly believed in the 20th century.
“We explore the possibility that animals’ minds are not always serious – and not always about the next action needed to survive,” said co-author Erica Cartmill of the University of California, Los Angeles (UCLA).
“It’s a serious study of a non-serious subject,” she added.
In the footage collected by researchers, members of all four great ape groups – gorillas, chimpanzees, bonobos and orangutans – exhibit the kind of prodding, provocative and playfully unpleasant behavior familiar to anyone who has spent time around young children.
The behavior, somewhere between play and aggression, followed a consistent trajectory. When monkeys sat around relaxed, one monkey – usually though not always a juvenile – would survey a target, usually an adult.
Then the teaser deliberately provoked the target, usually by poking, hitting, pulling or jumping on it – and then stepping back and waiting for a response.
This step at the end – which primatologists call “response looking” – was “particularly interesting,” says lead author Isabelle Laumer, a primatologist at the Max Planck Institute.
“They’re actually looking at the target, probably because they want to see their reaction,” Laumer said. If they didn’t get a response, the teaser generally tried again – only this time at a higher intensity.
A few other patterns stood out. First, adults and young people joked with each other in different ways: a young person might hit an adult, while an adult would just poke or tickle a young person.
And although young primates’ closest companions are often their mothers, mothers were not generally the target of teasing – although older sisters disproportionately were.
Adults usually greeted this teasing with half-hearted reprimands or withdrawals – pushing the teaser away, getting up and going elsewhere – although in about a third of cases they responded indulgently or playfully.
And while teasing patterns were very consistent across great ape species, among orangutans – a species known for their flowing orange locks – hair pulling was much more popular as a means of attracting attention than among their relatively short-haired people. cousins such as chimpanzees and bonobos.
These findings—like many others from the emerging research on animal cognition and sociality—straddle the line between the obvious and the revealing.
On the one hand, the findings represent scientific confirmation of something that anyone who has visited a primate enclosure at a zoo had a good chance of seeing.
In her previous work with great apes, Laumer said, “I have observed in the zoo that they sneak and move [each other’s] her from behind.”
This type of behavior is well represented in the scientific literature, noted by celebrities such as Jane Goodall and Frans de Waal.
“Juveniles in the chimpanzee colony of the Arnhem Zoo regularly ‘harass’ adult group members,” wrote primatologist Otto MJ Adang in a classic 1986 article.
Time and time again, Adang wrote, younger chimpanzees picked up adults and “threw sticks and sand at them, hit them from behind, etc., and immediately ran away. This happens without any apparent inducement and despite the fact that they could be punished.”
For decades, however, scientists tended to categorize this behavior as belonging to low-level overt aggression – described by words like “annoying,” “bullying” or “intimidation” – or as play.
For example, in Adang’s studies, he specifically excludes such provocations from the term “teasing” if they are performed with a characteristic primate expression known as a “play face.”
And a 2017 article refers to a similar cluster of behavior among bonobos as the “intimidation of adults by immature.”
But this ignores the way that teasing, joking and clowning exist somewhere between the two categories, said Cartmill of UCLA.
“There’s some teasing in the middle,” she said. “It has some characteristics of aggression – you do it to provoke a response – but within close relationships it is playful.”
An important element of these interactions, she noted, is that “they occur when animals are in a relaxed state—like two children in the backseat of a car seat on a road trip, poking each other. Or offer something and withdraw it, or lean very close to put my face near yours – ah, now you’re irritated.
This behavior can be playful, she said, but it is also different from play. “The non-scientific term is: they are their own deal.”
Cartmill recognized that this comparison of human children in the backseat to a pack of chimpanzees sounds a lot like an old bogeyman of animal behavioral science: anthropomorphism, or the idea (ubiquitous in children’s cartoons, for example) that animal behavior is analogous to human ones.
“Monkeys don’t tell sophisticated jokes,” she said, noting that even the simplest and most groan-inducing “dad joke” is often at a level of complexity that requires not only the ability to speak but also a deep command of a culture.
To launch an annual lecture on this point, Cartmill shows students a list of “horrible, eye-rolling jokes,” such as a cartoon showing a pickle with a top hat and walking stick with the caption “I’m quite a big dill.” ‘
“Understanding that joke – and even understanding why it’s a terrible joke – is something no other species can do,” she said.
But in a discipline that has often viewed animals as akin to complex machines that run unconsciously on program-like stimulus-response inputs, she said, obvious comparisons between humans and animals can provide a “reality check” to help scientists to ask better questions. .
And many of the comparisons are tempting. Laumer, Max Planck’s primatologist, pointed to a 2021 study by the paper’s UCLA co-author Sasha Winkler, which found a strong overlap between human laughter and “play sounds” in primates.
(That study hypothesized that the characteristic “ha ha” of human laughter “evolved from an auditory signal of labored breathing during playing.”)
Other studies have shown that one of the foundations of the idea that humor is human-specific—that at least enough language is needed to understand why that pickle is a big dill—doesn’t turn out to be true.
For example, human babies as young as eight months old already begin to play with the expectations of others, as shown in a 2015 article on the subject. “Before they speak, walk, or crawl, babies joke,” wrote scientists Vasudevi Reddy and Gina Mireault.
“Even in the first year of life, infants create and maintain new humorous initiatives,” they found, including “actively seeking opportunities to provoke laughter from others by playing the ‘clown’ and playfully provoking others by telling them plagues.”
Like those of young great apes, these toddler jokes are not particularly complicated: for example, they can be broad comic gestures, such as wearing a shoe on the head, or offering a toy to a parent and then withdrawing it.
These kinds of early, playful banter — which Tuesday’s research suggests is common among great apes — could form the building blocks of what eventually comes to be presented in our species as, for example, political cartoons and stand-up comedy, Cartmill said.
But for both young monkeys and young people, she said, it can also teach, reaffirm and reinforce valuable lessons about social norms and about the specific nature of individual family members — how much you can poke your brother before he gets really angry. relationships. (As Laumer said, quoting a German proverb: “Those who love each other tease each other.”)
After all, one core element of humor is that it is social: both young apes and human children seem to derive their understanding of what is funny – and what is scary or alarming – from the way adults and older youngsters react.
For toddlers, Mireault and Reddy write, “It is other people’s emotional responses—their laughter, amusement, outrage, surprise, annoyance, and confusion—that are the key to their funnyness, which ‘opens the doors’ to humor.”
This social context now represents the source of some of the biggest unanswered questions about the building blocks of humor in animals. Because the scientists looked at small groups of captive monkeys, they couldn’t investigate how joking occurs in more numerous or complicated social groups.
For example, does teasing occur more often in the presence of others than when both parties are alone – and does it matter whether those others are socially popular? And how does this behavior change in chimpanzees in the wild?
“I’m not saying monkeys joke,” Cartmill said, “but perhaps they have a culture of teasing that varies from group to group.”
To see those differences — or to notice them in species more distant than monkeys — will require moving beyond old assumptions about what animals are capable of, she argued.
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