Mother's little helpers: What we know (and don't know) about cooperative infant care in callitrichines

2018

Physiology & Behavior

Cooperatively breeding common marmosets raise their infants with the help of other adult group members, but individual care-taking contribution can vary considerably. We tested four hypotheses that may explain this variation within marmoset family groups. The pay-for-help hypothesis argues that allogrooming is used strategically by parents to pay helpers for helping. The pay-for-infant-access hypothesis claims that helpers use allogrooming as payment for infant-access. The intrinsic predisposition hypothesis suggests that more affiliative individuals are also more motivated for infant-care, and the relationship quality hypothesis that individuals involved in highly affiliative relationships with main caregivers contribute more to infant-care. To test these hypotheses, we followed five marmoset family groups over a total of eight reproductive cycles, and quantified affiliative behavior, infant-carrying, and food sharing over six to 12 weeks around infant-birth. We found no evidence for either the pay-for-help or pay-for-infant-access hypotheses nor did intrinsic prosocial predisposition determine individual infant-care. Mutual dyadic affiliation, however, was positively linked to infant-carrying and food sharing in female and male breeders and in male helpers. This suggests that cooperation during infant-care is mediated by relationship quality rather than strategic grooming in marmosets. Overall, these results may also contribute to a better understanding of cooperation in humans.

Section: Introductionmentioning

confidence: 99%

Why help? Relationship quality, not strategic grooming predicts infant-care in group-living marmosets

Finkenwirth

2018

Physiology & Behavior

“…Callitrichid monkeys, including common marmosets, show the highest levels of allomaternal care in non-human primates [1]. They typically live in extended family groups with a breeding pair and sexually mature helpers who may be more or less closely related [2,3]. All group members contribute to rearing offspring, mostly by carrying infants and sharing food with them.…”

Section: Introductionmentioning

confidence: 99%

“…A better understanding of these factors is crucial because this allows evaluation of different evolutionary scenarios of cooperative breeding. Likely ultimate explanations for cooperative infant care [3,10] are kin selection, gaining parenting experience, group augmentation, social prestige and pay-to-stay. Kin selection must have played a crucial role via indirect fitness benefits.…”

Section: Introductionmentioning

confidence: 99%

Reverse audience effects on helping in cooperatively breeding marmoset monkeys

Brügger

Kappeler-Schmalzriedt

2018

Biol. Lett.

Cooperatively breeding common marmosets show substantial variation in the amount of help they provide. Pay-to-stay and social prestige models of helping attribute this variation to audience effects, i.e. that individuals help more if group members can witness their interactions with immatures, whereas models of kin selection, group augmentation or those stressing the need to gain parenting experience do not predict any audience effects. We quantified the readiness of adult marmosets to share food in the presence or absence of other group members. Contrary to both predictions, we found a audience effect on food-sharing behaviour: marmosets would systematically share food with immatures when was present. Thus, helping in common marmosets, at least in related family groups, does not support the pay-to-stay or the social prestige model, and helpers do not take advantage of the opportunity to engage in reputation management. Rather, the results appear to reflect a genuine concern for the immatures' well-being, which seems particularly strong when solely responsible for the immatures.

“…Common marmosets (Callithrix jacchus) are cooperatively breeding callitrichid New World monkeys. Like other callitrichids, they live in cohesive family groups who cooperate in a variety of contexts, including group defense, food acquisition and caring for immatures (Digby et al 2007;Erb and Porter 2017;Garber 1997;Yamamoto et al 2014). Caretaking includes both infant carrying and sharing of food, which is frequent and performed by all group members, who in captivity may share up to 80% of all food items they obtain in food sharing tests (Finkenwirth et al 2016;Guerreiro Martins et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Marmoset prosociality is intentional

Schaik

2020

Anim Cogn

Marmoset monkeys show high levels of proactive prosociality, a trait shared with humans, presumably because both species rely on allomaternal care. However, it is not clear whether the proximate regulation of this convergent trait is also similar, in particular with regard to intentionality, which is a defining characteristic of prosocial behavior in the human literature. The aim of this paper was to investigate whether marmoset monkeys' prosociality fulfils the criteria of intentionality developed in primate communication research. The results show that marmoset prosocial behavior (i) has some degree of flexibility, since individuals can use multiple means to reach their goal and adjust them to specific conditions, (ii) depends on the presence of an audience, i.e. potential recipients (social use), and (iii) is goal-directed, because (a) it continues exactly until the putative goal is reached, and (b) individuals check back and look at/for their partner when their prosocial actions do not achieve the putative goal (i.e. if their actions don't lead to the expected outcome, this elicits distinct reactions in the actor). These results suggest that marmoset prosociality is under some degree of voluntary, intentional control. They are in line with other findings that marmosets perceive each other as intentional agents, and only learn socially from actions that are perceived as intentional. The most parsimonious conclusion is, therefore, that prosocial behavior is fundamentally under voluntary control in marmosets, just as it is in humans, even though our more sophisticated cognitive abilities allow for a far more complex integration of prosociality into a broader variety of contexts and of behavioral goals.