Chimps and Six-Year-Olds Want to Mete Out Punishment — Even If It Comes at a Cost

Experiments with chimpanzees and 4 to 6-year-old children show that members of both groups will make a personal sacrifice to see antisocial behavior punished.

When misfortune befalls another, humans and other animals often empathize and show concern for the suffering individual. If an individual suffers, yet is deemed to be antisocial and cruel, there is an entirely different reaction: We want to see punishment.

From medieval public hangings to the #MeToo movement, people are willing to invest their own time and resources to witness the enactment of justice, or at least what is perceived to be just. Sometimes pleasure is even derived in doing so — what we know of as schadenfreude.

Chimpanzees also incur costs to watch antisocial others being punished, reveals a new paper published in the journal Nature Human Behavior. Like humans aged 6 years and older, chimps want to see just punishment meted out, even if they have to pay for it in some way.

"More often than not, you see younger children 'outperform' chimpanzees, especially in terms of social skills and behavior," co-author Nikolaus Steinbeis of University College London told Seeker. "But here we actually see similarities, suggesting how deeply this desire for watching punishment might run."

The idea for the study came from senior author Tania Singer of the Max Planck Institute for Human Cognitive and Brain Sciences. She told Seeker that she had previously researched social emotions and motivation in humans, and now desired to look at "empathy and schadenfreude, and the need for revenge of unfair people, in non-human primates and to compare this behavior to children."

She approached co-author and renowned comparative psychologist Josep Call about the idea. They assembled their team and formulated a unique series of experiments.

RELATED: Comparison of Primate Brains Reveals Why Humans Are Unique

Seventeen chimps from the Leipzig Zoo were recruited for the non-human primate part of the study. The chimps included both males and females between the ages of 8 and 42.

Each chimp was separately brought into a room with a heavy, mesh, sliding door on one side that when pushed aside allowed the chimp visual access to an adjacent room. The experiment began with a human actor either being friendly with the chimp and offering food or teasing the chimp and being mean — preventing the chimp access to tasty snacks.

Another human actor, playing the role of "the punisher" then appeared. The punisher, wielding a stick, pretended to beat up either the friendly actor or the "mean" one, all while the victims cried out in supposed pain. The punishment took place for four seconds in full view of the chimp before moving to an adjacent room, which the chimp could only view if it pushed open the heavy door.

When the "good" person was punished, the chimps often vocalized by emitting worried barks, hoots, and whimpers, as if to protest the unfair treatment. The observing chimps did not slide the door further, indicating that they did not want to see the beating.

When the "bad" individual was punished, however, the chimps were less aroused. The majority were riveted to the action and went to a lot of trouble to push open the heavy sliding door, enabling a clear view of the beating.

For the part of the study concerning children, 72 boys and girls aged 4 to 6 were brought to the laboratory by at least one parent. Before they arrived, the parents were told to bring six of their child's favorite toys without their child noticing. Each child was then asked to watch a puppet show.

The first puppet told the child viewer that it wanted to play and then offered one of the child's favorite toys. This friendly puppet acted as promised and without hesitation handed over three of the child's coveted toys.

The antisocial puppet, however, held out each toy, as though it was going to give it to the child, but then quickly snatched it away.

Another puppet playing the role of "the punisher" then appeared. This "punisher puppet" first beat the friendly puppet and next the antisocial one as both victims cried out in supposed anguish. An assistant gave the children money tokens and informed them that they could continue to watch the punishment if they placed a token into a box to the left of the puppet show stage. They could do this up to four times.

The majority of the six-year-olds used their tokens to watch the antisocial puppet being punished, but did not wish to see the "good" puppet's beating. Both the visual and vocal expressions of the children — studied by the scientists — revealed that they rejoiced in the misfortune of the "bad" puppet. The four and five-year-old study participants showed no such bias.

"Six years of age is a very important time because it is also at this point when children are willing to incur costs to punish others' transgressions, even if they do not stand to gain anything from it," Steinbeis said. "Fair and prosocial behavior becomes very important to children."

From a physiological standpoint, the brain at this time develops an increasing number of connections between prefrontal and limbic brain regions, which the researchers said are likely involved in processing perceived justice.

From a social standpoint, children at this age usually begin first grade and spend more time with others. “[Schooling] is obviously very important in shaping children's social behavior," Steinbeis said.

The common ancestor of chimps and humans might have also been hardwired to seek justice given that chimpanzees share some behaviors with our species. It is also possible that other primates have these skills as well.

The abilities help with living in a small family, as well as larger groups.

"Having psychological mechanisms that ensure fairness in one's social environment is important in order to see fair or prosocial behavior thrive,” Steinbeis explained. “Such a mechanism of feeling reward when knowing that this happens is a pretty effective one because such a desire would make punishment more likely and be a stronger deterrent not to engage in antisocial behaviors."

RELATED: The Super Strength of Chimpanzees, Explained

The researchers used human actors for the chimp study and puppets for the children because they wanted to keep the level of difference between participants and players more or less comparable, Singer and Steinbeis said. The participants understood the action, but there was a slight disconnect between them and the players, so their experiences were similar.

It at first seems like quite a stretch to link reaction to a puppet show to an adult human's desire for justice, but the basic underlying brain mechanisms are the same.

While the researchers saw no real difference between male and female responses during the studies on chimps and children, prior research led by Singer suggests "that there are individual differences in the extent to which one might wish to see deserved punishment, something which in adults might be more present in men than in women," Steinbeis said.

"Such responses," he added, "can also be modulated by perceiving others to one's in and out-group."

Humans therefore tend to cheer wins for their team — be it in sports, politics, or some other shared belief or group — and conversely celebrate losses experienced by the opposing individuals. Often this is done in a playful way, but the same mechanisms gone awry could lead to an obsession with deadly punishment for perceived injustices, even if imagined or projected onto innocent others.

Steinbeis said that the latest studies are now within a wider research agenda looking at social behaviors, emotions, and motivations in humans and other primates. Future research may reveal more about what causes children, starting at age 6, to sacrifice resources in the interest of fairness. The scientists also hope to gain a better understanding of the evolutionary roots of this strategy in primates to maintain fair cooperation.

WATCH: We Finally Know Why Chimpanzees Cooperate With Each Other