Performance of sheep and goats in a delay of gratification task

Self-control, the ability to resist an immediate reward for a more beneficial delayed outcome, is an adaptive skill underlying decision-making. While widely studied in non-human primates and birds, its evolution remains debated. Factors such as brain size, metabolic rate, longevity, social complexity, or foraging ecology may shape self-control across species. To investigate further the link between these factors and self-control, we compared two domesticated ungulates, sheep (Ovis aries, n = 7) and goats (Capra hircus, n = 7), in a delay of gratification task. These species mostly differ on their level of social cohesion and foraging ecology but share a relatively similar evolutionary and domestication history. In our study, sheep waited for 54.3 ± 15.1 s while goats waited for 62.9 ± 13.8 s (group level mean ± SD). Some individuals from both species delayed gratification for up to 80 s. The moderate higher success rate of goats may relate to their feeding ecology as dispersed foragers or to their social flexibility compared to sheep. The two species adapted their decision according to different parameters, such as the duration of the upcoming delay or the relative values of the rewards and engaged in distraction behaviours to increase their success rate in waiting, indicating that they share common cognitive strategies. These findings suggest that factors such as social complexity or foraging ecology may shape self-control in these domesticated species.