Human Nature

, Volume 18, Issue 2, pp 109–124

Paleoclimatic Variation and Brain Expansion during Human Evolution



One of the major adaptations during the evolution of Homo sapiens was an increase in brain size. Here we present evidence that a significant and substantial proportion of variation in brain size may be related to changes in temperature. Based on a sample of 109 fossilized hominid skulls, we found that cranial capacities were highly correlated with paleoclimatic changes in temperature, as indexed by oxygen isotope data and sea-surface temperature. Indeed, as much as 52% of the variance in the cranial capacity of these skulls could be accounted for by temperature variation at 100 ka intervals. As an index of more short-term seasonal fluctuations in temperature, we examined the latitude of the sites from which the crania originated. More than 22% of the variance in cranial capacity of these skulls could be accounted for by variation in equatorial distance.


Cranial capacity Homo Paleoclimatic variability Seasonal variability Sea-surface temperature Variability selection 

Copyright information

© Springer Science & Business Media, LLC 2007

Authors and Affiliations

  1. 1.Department of PsychologyUniversity at Albany, State University of New YorkAlbanyUSA

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