Being Social Does Grow Your Brain...if you are a carnivore

Brain-size evolution and sociality in Carnivora

1. John A. Finarellia,b,1 and
2. John J. Flynnc

-Author Affiliations

1.
aDepartment of Geological Sciences, University of Michigan, 2534 C.C. Little Building, 1100 North University Avenue, Ann Arbor, MI 48109;
2.
bMuseum of Paleontology, University of Michigan, 1529 Ruthven Museum, 1109 Geddes Road, Ann Arbor, MI 48109; and
3.
cDivision of Paleontology and Richard Gilder Graduate School, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024

1.


Abstract:

Increased encephalization, or larger brain volume relative to body mass, is a repeated theme in vertebrate evolution. Here we present an extensive sampling of relative brain sizes in fossil and extant taxa in the mammalian order Carnivora (cats, dogs, bears, weasels, and their relatives). By using Akaike Information Criterion model selection and endocranial volume and body mass data for 289 species (including 125 fossil taxa), we document clade-specific evolutionary transformations in encephalization allometries. These evolutionary transformations include multiple independent encephalization increases and decreases in addition to a remarkably static basal Carnivora allometry that characterizes much of the suborder Feliformia and some taxa in the suborder Caniformia across much of their evolutionary history, emphasizing that complex processes shaped the modern distribution of encephalization across Carnivora. This analysis also permits critical evaluation of the social brain hypothesis (SBH), which predicts a close association between sociality and increased encephalization. Previous analyses based on living species alone appeared to support the SBH with respect to Carnivora, but those results are entirely dependent on data from modern Canidae (dogs). Incorporation of fossil data further reveals that no association exists between sociality and encephalization across Carnivora and that support for sociality as a causal agent of encephalization increase disappears for this clade.

No time to comment in depth. If tis holds up, it harpooned and dragged in a hypothesis that has been used repeatedly.