Abstract # 142:

Scheduled for Friday, August 19, 2005 05:10 PM-05:30 PM: Session 12 (Crystal Ballroom) Oral Presentation


PROBING THE GENETIC BASIS OF HUMAN BRAIN EVOLUTION

B. Lahn
University of Chicago, Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
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     Human evolution is characterized by a dramatic increase in brain size and complexity. Traditionally, efforts to study human brain evolution have focused on the anatomical and physiological differences between the human brain and that of the other taxa, as well as the behavioral manifestations of these differences. We sought to study human brain evolution from a genetics point of view. To this end, we examined the evolution of genes involved in diverse aspects of nervous system biology. We found that these genes display significantly higher rates of protein evolution in primates than rodents. Importantly, this trend is most pronounced for the subset of genes implicated in nervous system development. Moreover, within primates, the acceleration of protein evolution is most prominent in the lineage leading from ancestral primates to humans. Thus, the remarkable phenotypic evolution of the human nervous system has a salient molecular correlate, i.e., accelerated evolution of the underlying genes, particularly those linked to nervous system development. In addition to uncovering broad evolutionary trends, our study also identified many candidate genes, most of which are implicated in regulating brain size and behavior, that might have played important roles in the evolution of the human brain. More detailed analysis of these candidate genes found in several of them strong signatures of positive selection in the lineage leading to humans. Remarkably, some showed evidence of ongoing positive selection within anatomically modern humans.