A philosopher once wrote to Frans de Waal, explaining the flaw in the primatologist’s findings on what he calls “the emotional side of animal behavior.”
It was impossible that monkeys have a sense of fairness, the philosopher said, “because the sense of fairness was discovered during the French Revolution.”
On Monday, in a lively campus appearance hosted by UC Berkeley’s Greater Good Science Center, de Waal offered compelling evidence that capuchin monkeys — namesakes, though presumably not co-religionists, of an order of Catholic friars — not only recognize inequity, but are quick to challenge it.
Before a packed house at Sibley Auditorium, de Waal played a video of an experiment he’d done with pairs of capuchin monkeys, housed side by side in glass cages. In return for handing a pebble to a researcher, one monkey receives a bland piece of cucumber, which she’s happy to get — until she sees that her partner’s reward for the very same task is a tasty grape.
She gives it another try, but instead of a grape gets cucumber again. This time she hurls the cuke back at the researcher, rattles her cage, pounds the floor in angry protest. It’s a tantrum similar, in fact — as another video showed — to that of a human toddler who sees her older brother get a cookie, only to get half herself.
During de Waal’s experiments, he said, monkeys rewarded equitably rejected the cucumber just 5 percent of the time. If their partners received a grape, however, they refused their lower pay at a rate of 50 percent. And when partners were given a grape “for free,” without even having to pick up a pebble, rejections soared.
Such behavior, said the Dutch-born de Waal, now at Emory University, is further evidence that humans are not the only species to boast a moral code, and that morality is separate from God and religion. Instead, it’s related to what he calls the “prosocial tendencies” of primates and other animals, a self-awareness — and awareness of others — that gives rise to emotional responses like reconciliation, empathy and consolation.
“I’ve seen chimps kill each other,” said de Waal, “so I’m very fully aware of their competitive side.” After studying aggression in chimps as a student in the Netherlands, though, “It struck me that after fights they would come together, they kissed and embraced each other, and that was actually more interesting than the aggression itself.”
And chimps aren’t the only nonhuman animals with a bent for reconciliation. “There’s only one mammal that has been tested where it has not been found, and that’s a mammal many of you have at home,” de Waal said. “It’s a domestic cat.
“I’m a big cat lover,” he added, “and I’m still waiting for the magical moment.”
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