Chimpanzees are vengeful but not spiteful

Abstract

People are willing to punish others at a personal cost, and this apparently antisocial tendency can stabilize cooperation. What motivates humans to punish noncooperators is likely a combination of aversion to both unfair outcomes and unfair intentions. Here we report a pair of studies in which captive chimpanzees (Pan troglodytes) did not inflict costs on conspecifics by knocking food away if the outcome alone was personally disadvantageous but did retaliate against conspecifics who actually stole the food from them. Like humans, chimpanzees retaliate against personally harmful actions, but unlike humans, they are indifferent to simply personally disadvantageous outcomes and are therefore not spiteful.cooperation ͉ fairness ͉ other-regard ͉ punishment ͉ reciprocity P eople will willingly suffer a cost to punish others. Although this does not sound like a formula for cooperation, something that humans are exceedingly good at, theoretical models and experimental evidence show that in the absence of punishment, cooperation does not survive the degrading influence of free-riders (1). Punishment, in the biological sense, is a strategy that decreases the occurrence of a behavior, and it is typically selfish in that it provides a future benefit for the individual such as the reduction of harmful behavior received from others (2) † . Punishment can make an act of spite, incurring a cost to impose a cost on another individual, beneficial in the long run and is therefore a means to an end. Spite, on the other hand, is the decreasing of the welfare of another individual as an end in itself, just as proximate-level altruism has increasing the welfare of another as the ultimate end (3). Negative reciprocity makes spite selfish just as positive reciprocity does for altruism (4). We use the term ''spiteful'' for proximate-level spite to distinguish it from ultimate-level spite ‡ .A special form of punishment has been revealed in economic experiments such as the ultimatum and public goods games. This ''altruistic punishment'' (7) provides benefits in the form of increased cooperation to others, whereas the punisher alone bears the costs. It could be argued that on a short time-scale, such unselfish punishment is spitefully motivated, and altruistic outcomes are an unintended byproduct; to our knowledge, the underlying motivations behind altruistic punishment remain to be shown. What might motivate punitive and possibly spiteful behaviors is that, instead of acting solely selfishly and counting only one's own gains and losses, people appear to compare their outcomes with those of others and appraise the motives behind the actions of others. The punishment of others based on unfair outcomes (8, 9) or intentions (10-13) has been argued to be a central and possibly unique feature of human cooperation.There is currently controversy about whether nonhuman primates also have a sense of fairness (in the sense of personally disadvantageous outcomes). Capuchin monkeys (Cebus apella) and chimpanzees (Pan troglodytes) reject food offered b...

Punishment and spite, the dark side of cooperation

“…In the studies described above in which subjects could control and respond to outcomes, there did not appear to be any comparison of gains and losses relative to others (Jensen et al 2006(Jensen et al , 2007a. A paradigm that is widely used has subjects react to differential outcomes without being able to control them as a demonstration of inequity aversion.…”

“…Humans are not the only angry species; anger is basic emotion that probably has deep evolutionary roots (Darwin 1899;Burrows et al 2006;Parr et al 2007). In the punishment experiment described above, chimpanzees also showed signs of anger (displays and tantrums) when food was stolen from them, and anger was correlated with collapsing the food table (Jensen et al 2007a). However, although other species have primary emotions, secondary, social emotions such as moral outrage, pride, shame and guilt may be uniquely human (e.g.…”

“…To elucidate whether chimpanzees functionally punish non-cooperative behaviours, an experiment presented captive subjects with three different scenarios, all involving food loss ( Jensen et al 2007a). In the loss condition, the food was moved away from the subject by the experimenter to an empty, adjacent room; this was a baseline measure of general frustration to losing food.…”

Evolutionary precursors of social norms in chimpanzees: a new approach

“…Only on the level of veridical empathy a complete separation of self and other's 340 distress is achieved, enabling an appropriate response to the other's specific needs (Zahn- Furthermore, there is experimental evidence that chimpanzees -punish‖ conspecifics that steal 369 their food by pulling a rope that causes the food platform to collapse and the food to fall out 370 of the thief's reach (Jensen et al 2007). This experiment supports anecdotal observations that 371 chimpanzees treat food, including highly valued food such as meat, with remarkable -respect 372 for ownership‖ (Goodall 1971;Mitani 2009) and hence possibly expect others not to steal it.…”

Chimps don't just get mad, they get even

“…Virtually all of the work on other primates has focused on the willingness to provide benefits to conspecifics. In this issue, Jensen et al (9) turn the tables and examine chimpanzees' propensity to impose sanctions on familiar group members who commit transgressions.…”