Human sense of fairness evolved to favor long-term cooperation

September 18, 2014
Two adult females look on as a third eats a preferred food resource. Credit: Sarah Brosnan and the Keeling Center for Comparative Medicine and Research of MD Anderson Cancer Center

The human response to unfairness evolved in order to support long-term cooperation, according to a research team from Georgia State University and Emory University.

Fairness is a social ideal that cannot be measured, so to understand the evolution of in humans, Dr. Sarah Brosnan of Georgia State's departments of Psychology and Philosophy, the Neuroscience Institute and the Language Research Center, has spent the last decade studying behavioral responses to equal versus unequal reward division in other primates.

In their paper, published in the journal Science, she and colleague Dr. Frans de Waal of the Yerkes National Primate Research Center and the Psychology Department at Emory University, reviewed literature from their own research regarding responses to in primates, as well as studies from other researchers. Although fairness is central to humans, it was unknown how this arose. Brosnan and de Waal hypothesize that it evolved, and therefore elements of it can be seen in other species.

"This is the basis of lots of things in human society, from wage discrimination to international politics," Brosnan said. "What we're interested in is why humans aren't happy with what we have, even if it's good enough, if someone else has more. What we hypothesize is that this matters because evolution is relative. If you are cooperating with someone who takes more of the benefits accrued, they will do better than you, at your expense. Therefore, we began to explore whether responses to inequity were common in other cooperative species."

Brosnan and de Waal began their studies of fairness in monkeys in 2003, becoming the first in the field to report on this subject for any non- species, Brosnan said. This paper, titled "Monkeys Reject Unequal Pay," was published in Nature.

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A video describing the ultimatum game in chimpanzees. Credit: Darby Proctor, Frans de Waal and the Yerkes National Primate Research Center

In this study, brown capuchin monkeys became agitated and refused to perform a task when a partner received a superior reward for that same task. To view video footage of the study, visit http://www.youtube.com/watch?v=meiU6TxysCg. Since then, Brosnan has tested responses to inequity in nine different species of primates, including humans. She has found that species only respond to inequity when they routinely cooperate with those who are not related to them.

However, responding to getting less than a partner is not the only aspect of fairness. For a true sense of fairness, it also matters if you get more. Brosnan and de Waal hypothesize that individuals should be willing to give up a benefit in order to reach equal outcomes and stabilize valuable, long-term cooperative relationships. Thus far, this has only been found in humans and their closest relatives, the apes.

A juvenile capuchin monkey shows interest in the food held by the alpha male of his group. Credit: Frans de Waal

"Giving up an outcome that benefits you in order to gain long-term benefits from the relationship requires not only an ability to think about the future, but also the self-control to turn down a reward," Brosnan said. "These both require a lot of cognitive control. Therefore, we hypothesize that lots of species respond negatively to getting less than a partner, which is the first step in the evolution of fairness, but only a few species are able to make the leap to this second step, which leads to a true sense of fairness."

Explore further: Exploring reactions to inequality

More information: "Evolution of Responses to (Un)Fairness," by S.F. Brosnan et al. Science, www.sciencemag.org/lookup/doi/10.1126/science.1251776

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orti
1 / 5 (7) Sep 18, 2014
I sometimes marvel at the wonderful pliability of evolutionary theory. I'm sure if I could convince and evolutionist that grass is black, he would discover that it is an evolutionary inevitability. Something like global warming explains everything bad for phys.org.
kochevnik
5 / 5 (4) Sep 18, 2014
I sometimes marvel at the wonderful pliability of evolutionary theory. I'm sure if I could convince and evolutionist that grass is black, he would discover that it is an evolutionary inevitability. Something like global warming explains everything bad for phys.org.
"Evolutionist" isn't a science career path, christtard. Did you see such a discipline at the university? Or have you ever been to a university that didn't study bibles?
orti
1 / 5 (5) Sep 18, 2014
Ah, a wanderer in search of the soul of Russia. Ever wonder why it's never been found? The atheists sold it for power – and got nothing in return.
TheGhostofOtto1923
4.3 / 5 (6) Sep 18, 2014
"Evolutionist" isn't a science career path, christtard. Did you see such a discipline at the university? Or have you ever been to a university that didn't study bibles?
Actually there are many such disciplines.

Evolutionary biology
Evolutionary anthropology
Evolutionary neuroscience
Evolutionary physiology
Evolutionary psychology
Evolutionary Behavioral Sciences
etc

These include sub-disciplines as well;
Evolutionary biology: palaeontology, molecular biology, population genetics, and developmental biology, to name just a few. Many universities offer a major in Ecology and Evolution.

-This shows how widely accepted and very fruitful the theory has become.
kochevnik
5 / 5 (5) Sep 18, 2014
Actually there are many such disciplines.
Right, but no generic "evolutionist" although there are billions of 'religionists' with no discernible specialty apart from reproduction
I Have Questions
5 / 5 (2) Sep 20, 2014
You know if you dumb anti evolution people want to argue about whether or not a segment of science makes sense you should be commenting on quantum mechanics.
Goika
Sep 21, 2014
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Goika
Sep 21, 2014
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