Developmental changes in the sequential behavior of interacting timber wolf pups.

We used information statistics to quantify first-order sequential dependencies in the social behavior of two sibling wolf pups (Canis lupus). Sequential dependencies in the behavior of the individual pups increased between the first sample (18-32 days of age) and two later samples taken from 34-53 days and 64-106 days of age. Sequential dependencies between pups were greatest during the second age sampled. We relate these findings to changes in the importance and style of interactions. In the first 32 days, social co-actions primarily involved mutual mouthing and pushing. Between 34 and 53 days, when interactions frequently became aggressive, pups were most responsive to the actions of their partner and tail-raising predicted biting. By 64 days, play-chasing was the mode. By this age pups had formed a relationship, were less attentive to the specific actions of their partner, and biting was no longer predicted by tail-raising. These results illustrate the importance of considering demand characteristics in distinguishing capabilities from performance, and suggest that changing social organization may underlie developmental changes in behavior. We also speculate that during these play-like interactions, pups may gain control over expressive displays.