The primate semicircular canal system and locomotion

Fred Spoor; Theodore Garland; Gail Krovitz; Timothy M. Ryan; Mary T. Silcox; Alan Walker

doi:10.1073/pnas.0704250104

Contributed by Alan Walker, May 8, 2007 (received for review December 23, 2006)

Abstract

The semicircular canal system of vertebrates helps coordinate body movements, including stabilization of gaze during locomotion. Quantitative phylogenetically informed analysis of the radius of curvature of the three semicircular canals in 91 extant and recently extinct primate species and 119 other mammalian taxa provide support for the hypothesis that canal size varies in relation to the jerkiness of head motion during locomotion. Primate and other mammalian species studied here that are agile and have fast, jerky locomotion have significantly larger canals relative to body mass than those that move more cautiously.

Footnotes

^‖To whom correspondence should be addressed. E-mail: axw8{at}psu.edu
Author contributions: F.S., T.G., M.T.S., and A.W. designed research; F.S., G.K., T.M.R., and M.T.S. performed research; F.S., T.G., T.M.R., and A.W. analyzed data; and F.S., T.G., T.M.R., M.T.S., and A.W. wrote the paper.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/cgi/content/full/0704250104/DC1.
Abbreviations:
AGIL,
locomotor agility;
AIC,
Akaike information criterion;
BM,
body mass;
CT,
computed tomography;
GLS,
generalized least squares;
ML,
maximum likelihood.
Freely available online through the PNAS open access option.
© 2007 by The National Academy of Sciences of the USA