No Short‐Term Contingency Between Grooming and Food Tolerance in Barbary Macaques (Macaca sylvanus)

Abstract

The exchange of services such as allo-grooming, allo-preening, food tolerance and agonistic support has been observed in a range of species. Two proximate mechanisms have been proposed to explain the exchanges of services in animals. First, an animal can give a service to a partner depending on how the partner behaved towards it in the recent past. This mechanism is usually tested by examining the within-dyad temporal relation between events given and received over short time periods. Second, the partner choice mechanism assumes that animals give favours towards specific partners but not others, by comparing how each partner behaved towards them over longer time frames. As such, the partner choice mechanism does not make specific predictions on a temporal contingency between services received and given over short time frames. While there is evidence for a long-term positive correlation between services exchanged in animals, results for short-term contingencies between services given and received are mixed. Our study investigated the exchange of grooming for food tolerance in a partially provisioned group of Barbary macaques, by analysing the short-term contingency between these events. Tolerance over food was compared immediately after grooming and in control condition, using food of different shareability. We found no evidence that grooming increases food tolerance or decrease aggression around food in the short term. Food tolerance was affected by the shareability of the food and the sex of the partners. The exchanges of grooming and food tolerance in non-human primates may be little affected by recent single events. We suggest that long-term exchanges between services given and received and social partner choice may play a more important role in explaining social interactions than short-term contingent events.

Short-term reciprocity in macaque’s social decision-making

“…This negative result could be simply explained by the fact that our macaques did not reciprocate juice reward delivery. Recent ethological report show the absence of short term contingencies between grooming and food tolerance in a different species of macaques (Molesti and Majolo, 2015) and in bonobos (Goldstone et al, 2016). This is somehow consistent with our results and underline the singularity of food sharing behaviors (Watson and Caldwell, 2009).…”

Wild Vervet Monkeys Trade Tolerance and Specific Coalitionary Support for Grooming in Experimentally Induced Conflicts

“…However, few experiments have been conducted to test for conditional helping rules. A recent study [11] did not find evidence for short-term contingency between grooming and food sharing based on tolerance in Barbary macaques (Macaca sylvanus). Hemelrijk [8] observed such support contingencies in captive macaques but lacked controls that would allow distinguishing between direct and generalized reciprocity.…”

“…Research has focused on three important aspects: the short-and long-term trading patterns of grooming for itself and/or for other commodities like tolerance or coalitionary support [1,2], the issue of whether exchanges are a convincing example for reciprocity [3,4], and what decision rules underlie trading [5][6][7]. These issues remain largely unresolved due to the correlative nature of observational studies and the rarity of experimental studies [2,[8][9][10][11]. Here, we present a new experimental paradigm to address these questions in wild vervet monkeys (Chlorocebus pygerythrus).…”

Why mutual helping in most natural systems is neither conflict-free nor based on maximal conflict

“…This implies that the return investments are not 'all-or-nothing'; in fact, although effects that are conditional on recent grooming are present both in related/bonded pairs and in unrelated/non-bonded pairs, they come on top of different baseline levels for interactions without prior grooming. Various other experiments (with both positive and negative results; [47,[51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66]) and a large number of correlational studies [67] provide additional evidence for such graded mutually conditional investments in primates. Based on this extensive experimental and correlational evidence, we predict that graded mutually conditional investments are indeed common in primates and will be found also in other taxa.…”