Big brains, enhanced cognition, and response of birds to novel environments
- *Centre de Recerca Ecològica i Aplicacions Forestals, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain; ‡Bio-Protection and Ecology Division, P.O. Box 84, Lincoln University, and Landcare Research, P.O. Box 69, Lincoln, Canterbury, New Zealand; §School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom; and ¶Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montréal, QC, Canada H3A 1B1
-
Edited by Gordon H. Orians, University of Washington, Seattle, WA, and approved February 11, 2005 (received for review November 2, 2004)
Abstract
The widely held hypothesis that enlarged brains have evolved as an adaptation to cope with novel or altered environmental conditions lacks firm empirical support. Here, we test this hypothesis for a major animal group (birds) by examining whether large-brained species show higher survival than small-brained species when introduced to nonnative locations. Using a global database documenting the outcome of >600 introduction events, we confirm that avian species with larger brains, relative to their body mass, tend to be more successful at establishing themselves in novel environments. Moreover, we provide evidence that larger brains help birds respond to novel conditions by enhancing their innovation propensity rather than indirectly through noncognitive mechanisms. These findings provide strong evidence for the hypothesis that enlarged brains function, and hence may have evolved, to deal with changes in the environment.
Footnotes
-
↵ † To whom correspondence should be addressed. E-mail: d.sol{at}creaf.uab.es.
-
Author contributions: D.S., R.P.D., T.M.B., P.C., and L.L. designed research; D.S., R.P.D., T.M.B., P.C., and L.L. performed research; D.S. analyzed data; and D.S. wrote the paper.
-
This paper was submitted directly (Track II) to the PNAS office.
-
Abbreviations: BS-EC, brain size–environmental change; PIC, phylogenetically independent contrasts.
-
See Commentary on page 5306.
- Copyright © 2005, The National Academy of Sciences
