Many organisms encounter situations where they lackinformation required to successfully exploit a resource. Onestable strategy that may be particularly useful is a win-stay-lose-shift strategy, in which an individual continues toperform a behavior that has proven fruitful in the recent pastor otherwise shifts to a new behavior. Here we investigatewhether domestic dogs (Canis familiaris) use a win-stay-lose-shift strategy utilizing data from 326 puppies and 323 adultdogs on a repeated object-choice task. We found a significanteffect of previous-trial success on dogs’ subsequent searchpatterns. Specifically, dogs were more likely to shift searchlocations if they were unsuccessful on the previous trial.These findings suggest that puppies and adult dogs win-stay-lose-shift.

Cognition presents evolutionary research with one of its greatest challenges. Cognitive evolution has been explained at the proximate level by shifts in absolute and relative brain volume and at the ultimate level by differences in social and dietary complexity. However, no study has integrated the experimental and phylogenetic approach at the scale required to rigorously test these explanations. Instead, previous research has largely relied on various measures of brain size as proxies for cognitive abilities. We experimentally evaluated these major evolutionary explanations by quantitatively comparing the cognitive performance of 567 individuals representing 36 species on two problem-solving tasks measuring self-control. Phylogenetic analysis revealed that absolute brain volume best predicted performance across species and accounted for considerably more variance than brain volume controlling for body mass. This result corroborates recent advances in evolutionary neurobiology and illustrates the cognitive consequences of cortical reorganization through increases in brain volume. Within primates, dietary breadth but not social group size was a strong predictor of species differences in self-control. Our results implicate robust evolutionary relationships between dietary breadth, absolute brain volume, and self-control. These findings provide a significant first step toward quantifying the primate cognitive phenome and explaining the process of cognitive evolution.