Sour Grapes

Just as a human toddler will indignantly throw down a cracker if he sees his friend receive a cupcake, monkeys will turn down previously acceptable rewards—cucumbers—if their partners get sweet grapes for doing equal or less work.

In addition to revealing emotions such as grief and empathy, monkeys may have an innate sense of fairness, according to researchers at Emory’s Yerkes National Primate Research Center and the Living Links Center. In the first experimental demonstration of its kind, a team led by primatologists Sarah Brosnan and Frans de Waal have shown that non-human primates respond negatively to unequal reward distribution, a reaction often seen in humans based on a universal instinct toward fairness. The findings were published in the Nature journal.

In the study, researchers used cucumbers and grapes to test brown capuchin monkeys’ reaction to injustice. The monkeys consistently refused the cucumbers if they saw their partners receiving the grapes for the same effort or less.

These results support a developing school of thought about human behavior: that economic decision-making is based as much on an emotional idea of fairness as on rational considerations. Identifying such reactions in nonhuman primates offers insight into how these feeling-driven responses developed, providing new perspective on why people make certain economic decisions.

“People often forgo an available reward because it is not what they expect or think is fair,” Brosnan says. “Such irrational behavior has baffled scientists and economists, who traditionally have argued that all economic decisions are rational. Our findings in nonhuman primates indicate the emotional sense of fairness plays a key role in such decision-making.”—P.P.P.

How does prostate cancer become bone cancer?

A collaborative group of cancer researchers at Emory has been granted $7.6 million from the National Cancer Institute to study the pathways and mechanisms through which prostate cancer metastasizes to bone cancer. The project is led by Leland Chung, director of Urological Research in Emory’s Department of Urology. Nearly 90 percent of all men who die from prostate cancer experience bone metastasis.




© 2004 Emory University