Play is generally considered an immature affair. However, adult play is present in several
mammal species living in complex social systems. Here, I hypothesize that adult social play …

Comparative analyses are the backbone of evolutionary analysis. However, their record in
producing a consensus has not always been good. This is especially true of attempts to …

Highlights•Ball rolling by bumble bees fulfils animal play criteria.•Ball rolling can act as an
unconditioned rewarding stimulus.•Younger bees rolled more balls, with age patterns …

Within-group variation in sociality has been linked to correlates of fitness across vertebrates.
Individuals that form strong social bonds with a few partners, or are well integrated into a …

Play is one of the most difficult behaviors to quantify and for this reason, its study has had a
very rocky history. Social play is ephemeral, difficult to distinguish from the other so-called …

According to established background knowledge, playing is essential in human
development and a power remediation tool in clinical populations. In clinical interventions …

It is widely believed that juvenile male mammals typically engage in higher rates of rough
and tumble play (RTP) than do females, in preparation for adult roles involving intense …

Energy is a variable of key importance to a wide range of research in primate behavioral
ecology, life history, and conservation. However, obtaining detailed data on variation in …

Many studies highlight the correlation between social ties and fitness, yet often cannot
reveal how ties influence fitness. This review is aimed to facilitate the formulation and testing …

Adaptive functions of play can vary across species, and also within species, reflecting
behavioral ecology and evolutionary history. We evaluated juvenile play in Belding's ground …