Playing is an important part of growing up for both humans and animals. In animals, it appears to help them rehearse key behaviors, release pent-up energy, and strengthen bonds.
In terms of interspecies play, research has understandably focused on the hi-jinks between domestic animals such as dogs and humans.
But researchers in Italy who delved into play between horses and dogs discovered something quite remarkable. Their findings suggest deep evolutionary roots in the ability of some species to playfully interact.
They share what appears to be a common language of play that reduces the chance of fun antics escalating into aggression.
Researcher Elisabetta Palagi and colleagues from the University of Pisa point out that play between species requires each animal to have the capacity to correctly perceive and interpret signals from their play partners.
“Up to now, most studies have focused on dog-human play due to the important implications such studies have in understanding the peculiar relationship we establish with our pets,” the study team wrote in the journal Behaviourial Processes. “Here, we focused on social play between dogs and horses.”
For their study, they identified 20 videos of dog-horse social play from YouTube, in which each session lasted at least 30 seconds.
The study team then analysed the videos to identify species-specific patterns shown by the dogs and horses.
The researchers found that the rates of self-handicapping and variability in playful actions did not differ between the two interacting subjects, suggesting well-balanced playful tactics.
The horses and dogs involved in play displayed what they termed as a Relaxed Open Mouth — a widespread playful facial expression in mammals.
They also found what they describe as Rapid Facial Mimicry — an automatic response in which individuals quickly mimic the others’ expressions. This, they say, seems to have a role in mood sharing during social interactions.
This facial mimicry, already identified among dogs, seems to occur just as often between dogs and horses during play as it does between dogs.
Ultimately, the researchers found little difference found between the two species’ way of playing.
The authors found that, despite the differences in body size, their different evolutionary paths, and differences in their behavioural repertoire, dogs and horses were able to fine-tune their actions to reduce the chances of misunderstanding and aggression.
One of the future challenges will be exploring the role of developmental pathways and familiarity in shaping inter-species communication.
It could, they say, be the basis of a universal language of play.
The study team comprised Palagi, Veronica Maglieri, Filippo Bigozzi and Marco Germain Riccobono.
Levelling playing field: synchronization and rapid facial mimicry in dog-horse play
Veronica Maglieri, Filippo Bigozzi, Marco Germain Riccobono, Elisabetta Palagi.
Behavioural Processes, Volume 174, May 2020, https://doi.org/10.1016/j.beproc.2020.104104
The abstract of the study can be read here.