This Is Your Brain: The Guided Tour – Who Do You Trust?

In case you were wondering, a trusting relationship can be based on things other than just money. In this edition of “This Is Your Brain – The Guided Tour” we’ll meet scientists who devised a “critter café”, where chimpanzees could consider splitting their entrée with a trusted friend.

In the study led by Jan Engelmann and Esther Herrmann of Germany’s Max Planck Institute for Evolutionary Anthropology, fifteen chimps living in a Sanctuary in Kenya got to play the classic economic “trust game” using apples and bananas rather than cash.

Picture two chimps at adjoining tables in our imaginary café. Each animal has the option of pulling a “trust rope” or a “no-trust rope.” The no-trust rope yielded immediate access to food, but not the kind that chimps love. In human terms: the kale salad might be good for you, but you crave a cheeseburger.

If the chimp pulled the trust rope, however, a box of prized snacks like apples and bananas moved to its partner. The partner chowed down on some and then got to decide; do I share or not? Think of dinner with a friend: who gets that last slice of pizza?

A “trustworthy” chimp would send the rest of the food back to its pal, while an “untrustworthy” chimp kept the food for itself. When paired with their friends – identified by mutual grooming and other behaviors – the chimps were much more likely to choose the trust rope and its promise of favorite fruit.

The findings surprised the scientists since chimpanzee social life is often characterized by conflict, competition, and dominance. As Dr. Engelmann noted, “Our research suggests that chimpanzees are able to form friendships that are based on trust,”

Still no definitive word on how chimps split the check.

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