Publications [#139267] of Meredith L Bastian

Journal Articles

1. Barrickman, NL, Bastian, ML, Isler, K., van Schaik, CP, Life history costs of increased brain size: a comparative test using data from long-term studies of primates in the wild, Journal of Human Evolution (in press)
   (last updated on 2007/12/10)

   Abstract:
   The correlation between brain size and life history has been investigated in many previous studies, but the results of these studies often conflict, causing uncertainties about whether these two features coevolved. The reason for these disparities stems from the quality of data used in analyses, which often consists of a mixture of wild and captive values. The lack of rigor in compiling these data could obscure real relationships. In addition, the work of evolutionary ecologists that attempts to explain the variation in life histories focuses on the demographic variables such as mortality rate, and discounts or ignores the association between brain size and life history. This paper seeks to resolve these difficulties by (1) proposing an overarching hypothesis that encompasses the work of evolutionary ecologists and the work of natural historians; (2) testing the predictions of this hypothesis using rigorously compiled data. Our hypothesis proposes that increased brain size is adaptive because it increases the reproductive lifespan of the species, but this benefit can only be realized if the costs of growing and maturing a large brain are met. The costs and benefits are directly reflected in the length of the periods of life history. This balance between costs and benefits explains why evolutionary ecologists have found consistent relationships between growth periods and mortality rates. Our results demonstrate that large brain size relative to body size is significantly correlated with prolongation of all stages of developmental life history except the lactational period, and is significantly correlated with an extension of the reproductive lifespan. These results support the contention that the link between brain size and life history is caused by a balance between the costs of growing a brain and the benefits the brain provides.