Graduate student Daniel Horschler (right) is lead author and Assistant Professor Evan MacLean (Left) is a co-author on a recently published a paper in Animal Cognition titled “Absolute brain size predicts dog breed differences in executive function.” The research team used citizen science data from Dognition.com on over 7000 dogs from 74 breeds to find that breeds with larger brains perform better on measures of short-term memory and self-control (two components of executive function), but not on other cognitive measures (e.g., social cognition, physical reasoning, and inferential reasoning) even after accounting for variation in training history, visual perception based on skull shape, functional breed group classification, and genetic relatedness between breeds. This is the largest study of dog breed differences in cognition to date, and it builds on Dr. MacLean’s previous work across species linking brain size and executive function. Read the abstract below or access the full article here.
Abstract: Large-scale phylogenetic studies of animal cognition have revealed robust links between absolute brain volume and species differences in executive function. However, past comparative samples have been composed largely of primates, which are characterized by evolutionarily derived neural scaling rules. Therefore, it is currently unknown whether positive associations between brain volume and executive function reflect a broad-scale evolutionary phenomenon, or alternatively, a unique consequence of primate brain evolution. Domestic dogs provide a powerful opportunity for investigating this question due to their close genetic relatedness, but vast intraspecific variation. Using citizen science data on more than 7000 purebred dogs from 74 breeds, and controlling for genetic relatedness between breeds, we identify strong relationships between estimated absolute brain weight and breed differences in cognition. Specifically, larger-brained breeds performed significantly better on measures of short-term memory and self-control. However, the relationships between estimated brain weight and other cognitive measures varied widely, supporting domain-specific accounts of cognitive evolution. Our results suggest that evolutionary increases in brain size are positively associated with taxonomic differences in executive function, even in the absence of primate-like neuroanatomy. These findings also suggest that variation between dog breeds may present a powerful model for investigating correlated changes in neuroanatomy and cognition among closely related taxa. (Anthro News date: 1/18/2019)