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Non-human Primate Studies Inform the Foundations of Fair and Just Human Institutions


Experiments with human participants have inspired new theories to capture human social, economic, and justice preferences, and shed new light on the foundation of institutions that promote and support large-scale exchange. Another source of valuable data for informing this agenda derives from studies with non-human primates. Here, we argue that primate studies of social preferences provide behavioral evidence supporting the role of the brain as an evolved social record-keeping device. Our argument follows Dickhaut et al. (Accounting Horizons 24:221–255, 2010), who pointed to record-keeping as critical in enabling large-scale trade. Here, we note that record-keeping also underlies justice judgments in both personal exchange and large-scale trade. The reason is that evaluating whether an allocation is just requires tracking not only benefits that accrue locally, but also benefits for distant others. Further, if record-keeping is an evolved trait (as Dickhaut et al. in Accounting Horizons 24:221–255, 2010 suggest), then it seems reasonable to expect it to be evidenced not only in humans, but also in non-human primates. Indeed, we argue that evidence from non-human primate research supports the Dickhaut hypothesis, thus supporting the role of justice in the emergence of fair and efficient economic exchange.

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  1. Rubinstein (2006, p. 251), writes, “Why is animal behavior relevant? I have no idea. If the behavioral economists are trying to say that the behavior of human beings is rooted in their physical nature, I imagine they are right. Indeed, we are just flesh, blood and neurons. Even if we consider these experimental results relevant, a skeptical approach is recommended here as well.”

  2. “Studying behaviors in other species can inform us about the evolutionary trajectory of morality, helping us to understand how the behaviors evolved and which environmental characteristics were critical for their emergence (Brosnan, 2011, p. 23).”

  3. The connection to non-human primate studies was made by Dickhaut et al. (2010), which draws attention to two related studies: Shadlen and Newsome (2001), Fiorillo et al., (2003). In this article, we substantially expand on this point, and also draw new connections between record keeping and justice judgments.

  4. Those features include, for example, the revenue realization, expense-matching and cost management and conservatism, among others.

  5. Dickhaut et al. (2010, p. 221).

  6. Cultural adaptation refers to the evolved ability of humans to learn from each other. This paves the way for more rapid adaptation to the local environment, without the need for genetic evolution.

  7. It is interesting to note that this process might also be connected to “the evolution of other-regarding motives as empathy and social emotions like shame” (Boyd & Richerson, 2009). These emotions plausibly underlie reciprocal behaviors and aversion to inequity, and thus may provide an ultimate foundation for the human sense of justice.

  8. We are not aware of evidence of intentional non-reciprocation. However, as noted by a referee, it would be interesting to find evidence that primates create artifacts to remember where they stored food as a mechanism to avoid reciprocity by hiding resources to avoid detection.

  9. Not everyone agrees that food sharing is a demonstration of pro-social preferences. For example, Stevens (2004) argue that food sharing is predicated on avoiding harassment.

  10. While we focus largely on positive reciprocity, negative reciprocity is found in both human and non-human primate studies.

  11. To our knowledge, it is unclear whether the monkeys remember the actual exchange or that they are responding to a general sense of greater happiness with their partner.

  12. Indeed, reciprocity has been observed in many other experimental environments and species of non-human primates.

  13. Natural selection will increase behaviors that benefit the individual, though this need not imply that the ultimate motive selected by evolution is selfish. Indeed, some have argued that it could be quite pro-social.

  14. With information from a “reputation record”, one can avoid exchanging with disreputable partners and strengthen the relationship with reputable partners. Also, with the expectation that reputation matters for future economic exchanges, one has more incentives to be reciprocal.

  15. For human studies, see (Camerer, 2003), and non-human primates studies, see the works done by Brosnan and de Waal (2003), Brosnan et al. (2005), Brosnan et al. (2010), Fletcher (2008), van Wolkenten et al. (2007), Massen et al. (2010, 2011), Price and Brosnan (2012), previous issue, Bräuer and Hanus (2012), this issue. For work on other species, see Horowitz (2012), previous issue, Range et al. (2012), previous issue, Pierce and Bekoff (2012), previous issue, and Raihani and McAuliffe (2012), previous issue.

  16. A regular finding is that responses to inequity aversion often involve “punishment” (Fehr & Schmidt, 1999; Fehr & Gächter, 2002). In both human and non-human environments, such punishment can act to enforce pro-social norms (Fehr & Gächter, 2002; Brosnan & de Waal, 2002; Boyd, Gintis, Bowles., & Richerson, 2003; Fowler, Johnson, & Smirnov, 2005; Brosnan, 2011), however, active punishment may be rare in non-human primate studies. de Waal find increased aggressive resistance from the possessor of food towards food beggars who failed to groom them. Also there is some evidence of punishment from cleaner fish).

  17. It is interesting to speculate on the source of an aversion to advantageous inequality. It may be the case that this preference is due to non-human primates awareness of and consideration for future interactions with their partner. Alternatively, it might reflect an adaptive impulsive response determined sub-consciously.

  18. Some studies find no effect at all. Brosnan et al. (2010) finds male chimpanzees are more responsive to inequity, while Brosnan and de Waal (2003) report only female capuchin monkeys respond negatively to inequity.

  19. Note that this refers to the “reward” in non-human primates studies but the “endowment” in human studies.

  20. Responsiveness to social reference points underlies a number of disparate literatures in economics, including peer effects, responsiveness to competitive environments and a variety of findings regarding how to promote conformity to norms.

  21. i.e., Capuchin monkeys and chimpanzees.

  22. It should be emphasized that toleration is itself a complex decision process that arises even in relatively simple contexts, such as those faced by the participants in these experiments.


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Correspondence to Daniel Houser.

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Chen, J., Houser, D. Non-human Primate Studies Inform the Foundations of Fair and Just Human Institutions. Soc Just Res 25, 277–297 (2012).

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  • keywords
  • Non-human primate studies
  • Social preferences
  • Record keeping
  • Experimental economics