Document Type
Article
Publication Date
11-2013
Abstract
Cetaceans rival primates in brain size relative to body size and include species with the largest brains and biggest bodies to have ever evolved. Cetaceans are remarkably diverse, varying in both phenotypes by several orders of magnitude, with notable differences between the two extant suborders, Mysticeti and Odontoceti.We analyzed the evolutionary history of brain and body mass, and relative brain size measured by the encephalization quotient (EQ), using a data set of extinct and extant taxa to capture temporal variation in the mode and direction of evolution. Our results suggest that cetacean brain and body mass evolved under strong directional trends to increase through time, but decreases in EQ were widespread. Mysticetes have significantly lower EQs than odontocetes due to a shift in brain:body allometry following the divergence of the suborders, caused by rapid increases in body mass in Mysticeti and a period of body mass reduction in Odontoceti. The pattern in Cetacea contrasts with that in primates, which experienced strong trends to increase brain mass and relative brain size, but not body mass.We discuss what these analyses reveal about the convergent evolution of large brains, and highlight that until recently the most encephalized mammals were odontocetes, not primates.
Recommended Citation
Montgomery, S. H., Geisler, J. H., McGowen, M. R., Fox, C., Marino, L., & Gatesy, J. (2013). The evolutionary history of cetacean brain and body size. Evolution, 67(11), 3339-3353.
Comments
In compliance with the publisher’s copyright and archiving policies, this is a post-print version of the document. Post-print materials contain the same content as their final edited versions, but are not formatted according to the layout of the published book or journal.