Wolf (Canis lupus) hybrids highlight the importance of human-directed play behavior during domestication of dogs (Canis familiaris).

) using a standardized behavioral test applied to wolf hybrids and several dog breeds. Contrary to expectations, our study provides little support for collective behavioral alterations. Specifically, although we found that wolf hybrids were less playful and overall more fearful than dogs, we did not detect any differences in sociability or aggression between wolf hybrids and dog breeds. Instead, our results suggest that behavioral alterations during domestication do not necessarily occur in concert and point to an important, but previously overlooked, role of selection on play behavior directed at humans during the domestication of dogs. (PsycINFO Database Record (c) 2018 APA, all rights reserved).