Wolf pups more likely to play on equal terms with similarly aged partners https://www.sciencedaily.com/releases/2016/05/160511154151.html
"Scientists have hypothesized that to facilitate social play, individuals may act to maintain equality by following a "50:50 rule," where each player is 'winning' or 'losing' 50% of the time. For instance, instead of using offensive tactics during play, a dominant animal may show 'self-handicapping' to put itself at a disadvantage, allowing a subordinate to 'win.' The authors of the present study observed play styles in captive wolves, analyzing play interactions in puppy-puppy and puppy-adult pairs to test if the interactions adhered to the 50:50 rule. They found that play in wolf puppies did not appear to follow this rule. Puppy-puppy pairs consistently showed more equal play than puppy-adult pairs, although the degree of equality varied greatly. In puppy-adult pairs, however, the puppies engaged in self-handicapping and less offensive behaviors, rather than the adults." ‎- JustDuckie
"The authors propose that such behavior may act to reinforce the dominant adult and subordinate puppy hierarchy established outside of play, and hope that continued research in this area may provide further insight." ‎- JustDuckie