Fairness and economic behavior in human and nonhuman primates with distinguished professor and primatologist Dr. Sarah Brosnan

The PrimateCast

“You should always collaborate with your friends!”
- Sarah Brosnan
In this episode I am really excited to be able to bring to you an interview with Dr. Sarah Brosnan, Distinguished Professor of Psychology, Philosophy and Neuroscience in the Language Research Center at Georgia State University.
Dr. Ikuma Adachi, from Kyoto University's Center for the Evolutionary Origins of Human Behavior, also joined us for the interview.
Sarah Brosnan is probably best known for her work on inequity aversion in primates. Her early experiments published in Nature [Monkeys reject unequal pay] showed that capuchin monkeys are sensitive to what others receive for the same amount of work and reject unequal pay.
Note that the video of these experiments is absolutely delightful and should be required viewing for every student of nature, the nature of the mind, and probably bratty child out there. Check it out here: capuchin monkey fairness experiment.
In the interview, Sarah explains how inequity aversion is likely a key component of social knowledge, and likely evolved as a suite of abilities linked to prosocial behavior.
After discussing some of the nuts and bolts of experimentation and the challenges of interpretation, we move into Sarah's more recent line of research: comparative experimental economics.
What's fascinating about this work is that Sarah is testing multiple different species of primate - capuchins, macaques, chimpanzees, and humans - by setting them up with more or less identical experimental situations.
These experiments are really allowing Sarah and her colleagues to learn the mechanical foundations of how we make decisions; and how they may be the same or very different foundations to those of other species even when the outcomes - like being able to maximize the payoff in any given game - look exactly the same!
I learned a lot from Sarah in this interview, and had an absolute blast with this conversation! I hope you all enjoy this interview with Dr. Sarah Brosnan as much as I did.
Other topics discussed in the interview:

• “Let the monkeys show you the way” as a foundation for scientific discovery
• Maximizing interpretability through well-designed experiments … and follow-ups!
• How widespread inequity aversion is in the animal kingdom
• Whether spite is likely among the suite of emotionally-driven behaviors available to animals
• Getting into the weeds with games for game theorists
• Being careful not to confuse cause and consequence as mechanism and outcome
• testing cognition in group settings and all the chaos that brings

One final thought. At 24:14 of the interview, Sarah mentions a 2023 paper that demonstrates that bonobos are sensitive to inequity (Paywall). The author, whose name

The PrimateCast is hosted and produced by Andrew MacIntosh. Artwork by Chris Martin. Music by Andre Goncalves. Credits by Kasia Majewski.

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