Where Next? Group Coordination and Collective Decision Making by Primates

Abstract

Primate groups need to remain coordinated in their activities and collectively decide when and where to travel if they are to accrue the benefits and minimize the costs of sociality. The achievement of coordinated activity and group decision making therefore has important implications for individual survival and reproduction. The aim of this special issue is to bring together a collection of empirical, theoretical, and commentary articles by primatologists studying this rapidly expanding topic. In this article, we introduce the contributions within the special issue and provide a background to the topic. We begin by focusing on decisions that involve a collective transition between a resting and a moving state, a transition we term making the move. We examine whether specific predeparture behaviors seen during transitions represent intentional processes or more simple response facilitation. Next we classify decisions according to the contribution of individual group members, and describe how, and why, certain individuals can have a disproportionate influence over group-mates' behavior. We then review how primate groups make decisions on the move. In particular, we focus on how variability in group size and spatial organization helps or hinders information transmission and coordination. We end with a discussion of new tools and methodology that will allow future investigators to address some outstanding questions in primate coordination and decision-making research. We conclude that a better integration of concepts and terminology, along with a focus on how individuals integrate environmental and social information, will be critical to developing a satisfactory understanding of collective patterns of behavior in primate systems.

Context-dependent hierarchies in pigeons

“…The dissociation between dominance and leadership in pigeons suggests that pigeons have a different mechanism, either of dominance or of leadership, compared with species where dominants lead (e.g., gray wolves, chacma baboons) (7,9,30). In common with those species, dominance in pigeons is associated with aggression and large body size.…”

Group personality during collective decision-making: a multi-level approach

“…This personality, corresponding to a consistent and correlated behaviour across time or situations, concerns a wide variety of traits such as boldness-shyness, exploration-avoidance, activity level, sociability or aggression [9]. Hence, from an evolutionary and ecological perspective, different populations across the animal kingdom show stable interindividual behavioural variations in the absence of demographic or morphological correlations [3,[9][10][11][12][13][14][15][16]. The most recent theory assumes that these personality traits play an important role for fitness in context-dependent ways: dominance, reproductive success or competitive abilities [8,10,13,17].…”

Ants work harder during consensus decision-making in small groups

“…During tasks such as collective movements, groups must reach a consensus over which action to pursue if group integrity is to be maintained [1,[3][4][5][6]. These decisions may be shared, with all group members contributing to the outcome, or unshared, with a distinct leader always initiating the decision [7].…”

“…These decisions may be shared, with all group members contributing to the outcome, or unshared, with a distinct leader always initiating the decision [7]. In a wide range of animals including fish [8], some primates [5] and insects [9,10], decisions are shared among a variable proportion of the group, and a group-level consensus manifests as an emergent product of the combined actions of multiple individuals [1,4]. Shared decisions allow information to be pooled, and this 'wisdom of the crowds' effect has long been recognized as a means by which groups can make more accurate decisions than individuals [3,[11][12][13][14][15][16].…”