Indiscriminate sociality: puppies do not preferentially re-engage a human partner after joint social play is interrupted

The ability to form joint intentions (i.e. engaging in activities that reflect a shared commitment between at least two individuals to reach a common goal) is well documented in humans. Recent research highlights the possibility that other species, such as bonobos, Pan paniscus , and domestic dogs, Canis familiaris , may also possess components of joint intentionality. Additionally, comparative developmental studies suggest that humans, but not bonobos, possess mechanisms required to form joint intentions from infancy. In the current study, we tested whether behavioural markers of shared intentionality observed in adult dogs are also present early in dog ontogeny. Answering this question will not only help determine which underlying mechanisms may be required for joint intentionality, but also whether humans are uniquely predisposed relative to other species. One way researchers have tested for behavioural indicators of joint intentionality is to assess whether a subject attempts to re-engage a recalcitrant partner after a joint activity is interrupted. Here, we tested a sample of ∼8-week-old retriever puppies ( N = 80) using the re-engagement task protocol designed by Horschler et al. (2022, Animal Behaviour, 183 , 159–168). Contrary to findings from adult dogs, puppies did not preferentially re-engage their previous play partners in a triadic activity following an interruption. Puppies did display a high frequency and variety of social behaviours towards both experimenters in the task, but not in a way that was obviously relevant to the interrupted triadic activity. These findings suggest that although adult dogs possess a key marker of joint intentionality, puppies may not. The difference in ontogenetic onset of this skill between humans and other species may be key to uniquely human sociality. The discrepancy in the ability to form joint intentions may therefore have motivational and/or cognitive–developmental underpinnings that are lacking in young puppies and should be explored further.