Evolution

Building Bigger Brains

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Science  04 Nov 2011:
Vol. 334, Issue 6056, pp. 571
DOI: 10.1126/science.334.6056.571-b

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Relative to those of other mammals, the human brain is exceptionally large, although how such a large size evolved is a mystery. Zhang et al. investigated differences in genes that are expressed in developing and adult brains in humans and in mice through gene expression profiling. They found an excess of evolutionarily new genes (primate-specific), of diverse functional types, expressed in the developing brains of humans as compared to the mouse. Furthermore, by profiling 13 developing brain regions, the authors observed that many of these genes were more highly expressed in the developing neocortex, one of the most expanded regions of the human brain relative to those of other primates. On the basis of these results, the authors suggest that changes in the regulation of young genes during neural development may have been responsible for the evolutionary changes that account for our large brain size.

PLoS Biol. 9, e1001179 (2011).

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