Calculated reciprocity after all: computation behind token transfers in orang-utans

Abstract

Transfers and services are frequent in the animal kingdom. However, there is no clear evidence in animals that such transactions are based on weighing costs and benefits when giving or returning favours and keeping track of them over time (i.e. calculated reciprocity). We tested two orang-utans (Pongo pygmaeus abelii ) in a token-exchange paradigm, in which each individual could exchange a token for food with the experimenter but only after first obtaining the token from the other orang-utan. Each orang-utan possessed tokens valuable to their partner but useless to themselves. Both orangutans actively transferred numerous tokens (mostly partner-valuable) to their partner. One of the orang-utans routinely used gestures to request tokens while the other complied with such requests. Although initially the transfers were biased in one direction, they became more balanced towards the end of the study. Indeed, data on the last three series produced evidence of reciprocity both between and within trials. We observed an increase in the number and complexity of exchanges and alternations. This study is the first experimental demonstration of the occurrence of direct transfers of goods based on calculated reciprocity in non-human-primates.

Grooming in mandrills and the time frame of reciprocal partner choice

“…Schino et al [2007] noted that hypothesizing that reciprocation could be constrained by animal cognitive limitations amounts to assuming that all forms of reciprocation are proximately supported by what Brosnan and de Waal [2002] labeled ''calculated reciprocity''. In fact, calculated reciprocity seems to be extremely rare, the first convincing case being recently documented by Dufour et al [2009] in a single pair of orang utans (Pongo pymaeus). On the contrary, the observation that reciprocal partner choice is widespread among primates [reviewed in Schino & Aureli, 2009], together with the evidence reported in this and previous studies that reciprocity is not necessarily immediate, suggest some form of attitudinal reciprocity [de Waal, 2000;Brosnan & de Waal, 2002] supported by emotionally based bookkeeping constitute the most likely proximate mechanism underlying primate reciprocity.…”

Lack of prosociality in great apes, capuchin monkeys and spider monkeys: convergent evidence from two different food distribution tasks

“…Following previous studies [27,29,30], we did not train subjects to reach a criterion. However, most of the subjects and species included in our study had already exchanged objects for food in previous studies [42][43][44][45][46] and all subjects readily exchanged tokens in this study (see the electronic supplementary material, table S1). In retrospect, our results highlight the importance of assessing whether …”

How can social network analysis improve the study of primate behavior?

“…Tests of symmetry will also advance the outstanding question of the function of grooming relationships, and whether individuals groom an individual in return for grooming, or for other commodities, e.g. tolerance at feeding sites or coalition support [Dufour et al, 2009;Fruteau et al, 2009;Kanngiesser et al, 2011;Pelé et al, 2010]. In this way, the term ''symmetrical'' can be replaced by the term ''reciprocal'' [Hemelrijk, 1990;Whitehead, 2008].…”