Analysing the evolution of brain size in three clades of carnivora using model selection

The evolution of brain size is a contentious topic, spawning numerous hypotheses on what drives it. In this study, we analyse and take several of them, and apply those theories to be tested on. We used a dataset by combining two forms of secondary data, the first on the brain sizes of various mammals within the families of Procyonidae, Mustelidae and Herpestidae and the second on the life history of members of carnivora, producing a dataset comparing the life histories of species within Procyonidae, Mustelidae and Herpestidae with their brain sizes, body mass, and encephalization quotients. We then ran several generalised linear models and used Aikake’s information criterion to select the best ones through model selection, then analysed the results. We found that environmental (arboreal, aquatic and fossorial) and dietary (cephalopods and durophagy) factors were associated with the evolution of brain size. Further, body mass was associated with environmental factors (arboreal and fossorial), dietary factors (cephalopods, durophagy, fish and insects), and activity time (nocturnal and diurnal). Encephalization quotient (EQ/EI) correlated weakly with some factors but were not significant. Our model suggests that the evolution of brain volume (and body size) is mediated by dietary and environmental factors. In particular, when the life history of the selected species showed significant amounts of time spent on water and land (amphibiousness), brain volume increased and body size didn’t. This suggests that amphibious mammals may have larger brain volumes than their terrestrial counterparts, although results from the encephalisation quotient tests didn’t support this.
Our data suggests environmental and dietary factors did drive the evolution of brain size.