Human frontal lobes are not relatively large
- 13 May 2013
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 110 (22), 9001-9006
- https://doi.org/10.1073/pnas.1215723110
Abstract
One of the most pervasive assumptions about human brain evolution is that it involved relative enlargement of the frontal lobes. We show that this assumption is without foundation. Analysis of five independent data sets using correctly scaled measures and phylogenetic methods reveals that the size of human frontal lobes, and of specific frontal regions, is as expected relative to the size of other brain structures. Recent claims for relative enlargement of human frontal white matter volume, and for relative enlargement shared by all great apes, seem to be mistaken. Furthermore, using a recently developed method for detecting shifts in evolutionary rates, we find that the rate of change in relative frontal cortex volume along the phylogenetic branch leading to humans was unremarkable and that other branches showed significantly faster rates of change. Although absolute and proportional frontal region size increased rapidly in humans, this change was tightly correlated with corresponding size increases in other areas and whole brain size, and with decreases in frontal neuron densities. The search for the neural basis of human cognitive uniqueness should therefore focus less on the frontal lobes in isolation and more on distributed neural networks.This publication has 42 references indexed in Scilit:
- Primate Prefrontal Cortex Evolution: Human Brains Are the Extreme of a Lateralized Ape TrendBrain, Behavior and Evolution, 2011
- Patterns of differences in brain morphology in humans as compared to extant apesJournal of Human Evolution, 2011
- The Evolution of Syntax: An Exaptationist PerspectiveFrontiers in Evolutionary Neuroscience, 2011
- Coordinated scaling of cortical and cerebellar numbers of neuronsFrontiers in Neuroanatomy, 2010
- The human brain in numbers: a linearly scaled-up primate brainFrontiers in Human Neuroscience, 2009
- Erratum: The delayed rise of present-day mammalsNature, 2008
- Cortical dopaminergic innervation among humans, chimpanzees, and macaque monkeys: A comparative studyNeuroscience, 2008
- Functional Trade-Offs in White Matter Axonal ScalingJournal of Neuroscience, 2008
- The delayed rise of present-day mammalsNature, 2007
- Understanding primate brain evolutionPhilosophical Transactions B, 2007