Playfulness is serious business. Scientists have gone to great lengths to solve the mystery of why animals play, with varying success.
Whether and how it benefits dogs, it seems their frolicking is good for humans – and surprisingly, it’s higher in breeds that work hard, according to European researchers.
They confirmed other suggestions that playfulness was favoured early in dog breeding and domestication and found this trait could be important for functions such as high trainability, says lead author Niclas Kolm, from Stockholm University in Sweden.
“High levels of human directed play behaviour is particularly important in dogs that work closely with their owners and trainers; for instance to retrieve quarry or help herding of livestock.”
Unlike their wolf ancestors, domestic dogs love to play, even as adults, whether it be with their canine friends, other animal species, humans or even objects. And there are many theories about why they do this.
Kolm’s team was interested in how behavioural evolution can be shaped by artificial selection, focussing on dogs’ human-directed play behaviour.
To explore this, they compared the level that different breeds play with humans in nearly 90,000 dogs from 132 breeds using data collected by the Swedish Kennel Club, combined with American Kennel Association breed categorisation.
These were grouped into herding, hound, non-sporting, sporting, terrier, toy and working dogs, and analyses controlled for shared ancestry and gene flow between them.
Results showed that dog ancestors already displayed playful behaviours that are found in several modern breeds and these aligned well with the arbitrary groupings. Notably, herding and sporting breeds showed more playfulness than non-sporting and toy breeds.
“The ancestral reconstruction showing intermediate levels of play with humans in the early breeds suggests that playful dogs were being chosen early because they are easier to work with – or just most fun to have around,” says Kolm.
“Then the analysis showed that the trait has evolved up and down during the breeding of the different functions and is currently most striking in the breed functions that require the closest work relationship between dogs and trainer/owner.”
These breeds include retrievers, pointers and collies that work closely and maintain eye contact with humans, and the authors suggest playfulness could help build a strong bond between dog and handler.
The research paper is published in the journal Biology Letters.