Chimpanzees monopolize and children take turns in a limited resource problem

Abstract

Competition over scarce resources is common across the animal kingdom. Here we investigate the strategies of chimpanzees and children in a limited resource problem. Both species were presented with a tug-of-war apparatus in which each individual in a dyad received a tool to access a reward, but tools could not be used simultaneously. We assessed the equality of tool use as well as the frequency of turn taking. Both species managed to overcome this conflict of interest but used different strategies to do so. While there was substantial variation in chimpanzee behaviour, monopolization was the common course of action: tool use was asymmetric with individual chimpanzees monopolizing the resource. In children, turn-taking emerged as the dominant strategy: tool use was symmetric and children alternated access to the tool at a high rate. These results suggest that while both species possess strategies for solving limited resource problems, humans might have evolved species unique motivations and socio-cognitive skills for dealing with such conflicts of interest.

Young children’s moral judgments depend on the social relationship between agents

“…Highlighting their equal footing, 3-year-olds share their resources with peers when their peer gets fewer rewards than them after collaboration (Hamann et al, 2011). Fiveyear-olds actively coordinate and help each other by employing fair strategies such as turntaking to ensure an equal outcome in collaborative tasks (Grueneisen & Tomasello, 2017;Knofe et al, 2019;Melis et al, 2016). Around ages 3 to 4, children start paying attention to who their peer partners are: they act more generously towards friends than towards strangers or disliked peers (Birch & Billman, 1986;Moore, 2009) and towards in-group than towards out-group peers (Renno & Shutts, 2015).…”

Chimpanzees engage in competitive altruism in a triadic Ultimatum Game

“…Therefore, it does not come as a surprise that apes were particularly motivated to outcompete their partners when the returning bene ts could still be high while the standing offers were still lower or equal to half of the total value. However, during the early test sessions their probability of offering more as second proposers was still lower than chance, possibly due to their initial predisposition to keep most of the rewards for themselves 32,33 . Another plausible explanation is that, even though chimpanzees showed signs of strategizing, they primarily focused on their own offers and on what the responder was accepting.…”

Communicative roots of complex sociality and cognition: neuropsychological mechanisms underpinning the processing of social information

“…Group-living involves substantial costs, as group mates have different fitness interests and compete for limited resources, including food, social partners and mates [42]; in addition, it is well-established that the stresses arising from group-living can have a direct impact on primates' fitness [43]. The ability of dominant group members to physically harm subordinate individuals, and monopolise their resources during competition [44,45] can act as a centrifugal force that, if unchecked, drives individuals apart and results in the group dispersing. In particular, subordinate females are exposed to higher rates of aggression from group mates, and those without access to social support have higher stress levels [46], reducing fitness through its effect on female fertility [47].…”

“…Through the course of hominin evolution, there was an increase in both brain size and group size, leading to selection pressures for more efficient mechanisms of social bonding than grooming [1]. As group size increases, there is a greater number of differentiated social relationships to monitor and a greater risk of monopolization of ecological and social resources by dominant members of the group [44,45], leading to stresses that would reduce the coherence of the group in the absence of social bonding mechanisms. When humans expanded into drier habitats with lower resource availability, these stresses would have increased, demanding more efficient bonding mechanisms.…”

“…R. Soc. B 377: 20210295 [44,45], leading to stresses that would reduce the coherence of the group in the absence of social bonding mechanisms. When humans expanded into drier habitats with lower resource availability, these stresses would have increased, demanding more efficient bonding mechanisms.…”