First report of food sharing among nicobar long-tailed macaques

Abstract

it is a very rare phenomenon. Here we provide the first descriptive report of food sharing in wild macaques. We studied two free-ranging groups of Nicobar long-tailed macaques from two different islands (i.e., Great Nicobar and Katchal), that have very different ecological settings and vegetation, for over 168 days. Using focal animal sampling, we observed a total of 18 food sharing events, that revolved around monopolizable food items (coconut and termite log) and mostly involved males. Females, even when present near the food owner, took very little interest in observing the event. The macaques shared food only among the individuals who sat close to the food owner, who, in turn, displayed very little aggression against bystanders. Given that, among Nicobar macaques, males have been previously described as forming strong social relationships, and since harassment was rarely observed in the present study, we argue that our observations could support the reciprocal exchange rather than the harassment hypothesis. While more observations are needed to better clarify the ultimate function of food sharing in this species, our study on Nicobar long-tailed macaques, highlighting some features that might make this species an ideal model to study the evolution of human behavior.

Where do we stand with the covariation framework in primate societies?

“…Sex differences are another challenge to the case for covariation. Critics charge that trait covariation only applies to females, as (1) few males have been included in comparative studies, (2) the social style of males differs from that of females, and (3) the behavior of males does not correlate with that of females (Balasubramaniam et al, 2020; Mazumder & Kaburu, 2021; Schülke & Ostner, 2008; Tyrrell et al, 2020). As regards the first issue, it is true that given the uneven sex ratio of macaque social groups, adult males were often less represented than adult females as study subjects, and that females became the standard subjects for the comparison of species on a quantitative basis (Balasubramaniam et al, 2012, 2018; Berman & Thierry, 2010; de Waal & Luttrell, 1989; Petit et al, 1997; Rebout et al, 2020; Thierry et al, 2008).…”

Mechanisms of equality and inequality in mammalian societies

“…females philopatric; mixed sexes; folivore/frugivore (food mostly not defendable) coalitions (N, R, CH) [54] co-feeding limited to kin [60] inequity aversion to unequal food reward [86] post-conflict reconciliation [67] long-tailed macaque (M. fascicularis) females philopatric; mixed sexes; frugivore (food is defendable) coalitions (N, R) [54] reciprocal exchange of food among non-kin [87] inequity aversion to unequal pay (food) paradigm [64] post-conflict reconciliation [67] rhesus macaque (M. mulatta)…”

“…By contrast, bonobos share food in the absence of conflict [70] and their co-feeding among non-kin enhances social interactions [69,71]. Many baboons and social carnivores share food (table 1), particularly with close kin [166]; brown capuchins ( Cebus apella ) [188], ravens [189] and long-tailed macaques ( M. fascicularis ) [87] also share with non-kin. Moreover, mutual tolerance between males and females maintains social bonds in Guinea baboons ( P. papio ) [190] to domestic dogs ( Canis lupus familiaris ) [191].…”