Critical issues in experimental studies of prosociality in non-human species

Abstract

Prosociality and acts of altruism are defined as behaviours which benefit another with either no gain or some immediate cost to the self. To understand the evolutionary origins of these behaviours, in recent years, studies have extended to primate species; however, studies on non-primates are still scarce. In light of the fact that phylogenetic closeness to humans does not appear to correlate with prosocial tendencies, but rather differences in the propensity towards prosociality may be linked to allomaternal care or collaborative foraging, it appears that convergent selection pressures may be at work in the evolution of prosociality. It would hence seem particularly important to extend such studies to species outside the primate clade, to allow for comparative hypothesis testing of the factors affecting the evolution of prosocial behaviours. In the current review, we focus on the experimental paradigms which have been used so far (i.e. the prosocial choice task, helping paradigms and food-sharing tests) and highlight the strengths and weaknesses of each method. In line with the aim of encouraging a broader comparative approach to the topic of prosociality, particular emphasis is placed on the methodological issues that need to be taken into account. We conclude that although a number of the paradigms used so far may be successfully applied to non-primate species, there is a need to simplify the cognitive demands of the tasks and ensure task comprehension to allow for a ‘fair’ comparative approach of prosocial tendencies across species.

Evaluating the self‐domestication hypothesis of human evolution

“…However, experts have long agreed that “the human‐directed selection that we associate with modern domestic populations (for commercial traits or fashion) would only have been possible after animal populations adapted to take advantage of the human environment, a process that took place, at least initially, in the absence of active human instigation” (Larson and Fuller). Domestication is therefore currently understood as a multi‐stage process characterized by a growing relationship between humans and animals . The process often starts with anthropophily.…”

“…For an understanding of the HSD hypothesis, it is important to make a distinction between domestication and improvement traits . Improvement traits result from the intense selection, in some cases leading to formally recognized breeds—some used as pets, some managed for economic reasons, many of great importance for human life . In these cases it is best to refer not to domestication but to selective breeding.…”

“…Domestication is therefore currently understood as a multi-stage process characterized by a growing relationship between humans and animals. 27 The process often starts with anthropophily. Among the various subsequent "pathways" to domestication, commensalism is the most widely assumed (e.g., for dogs), but a "direct" and a "prey" pathway have also been proposed for several species.…”

Mesotocin influences pinyon jay prosociality

“…From helping injured nest-mates in ants to donating to charities in humans, many species exhibit prosocial behavior , in which they behave in a way that benefits another individual [1]. In mammals, the neuropeptide oxytocin is a critical hormone regulating social behavior s, including prosociality.…”

Social manipulation in nonhuman primates: Cognitive and motivational determinants

“…In particular, species of particular relevance with regard to their phylogenetic position or their socioecology should be targeted while using standardized methods (as illustrated by recent studies, see Amici et al, 2014a;Burkart et al, 2014). To achieve this, simple setups are required that do not require extensive training or technical knowledge (see Albiach-Serrano 2015), especially to facilitate comparisons with non-primates (Marshall-Pescini et al, 2016). Physiological measures of emotional responsivity and arousal (such as pupil dilation, e.g., Hepach et al, 2012;and thermal imaging, e.g., Kano et al, 2016) may allow to detect other-regarding preferences and related cognitive biases (such as inequity aversion) even if they are not manifested 55 behaviorally.…”