Brain Science: New Syntheses
Wednesday, April 18, 2007
Presented by the New York Academy of Sciences
The New Vistas Lecture Series has been created to celebrate the Academy's move to our new downtown home. In this series, the Academy has invited highly accomplished scientists to serve as hosts for an evening of "science at the frontiers." Each evening will feature talks by two up-and-coming scientists whose work has been identified by the host as exceptionally worthy of the spotlight. The New Vistas Lecture Series is free to nonmembers.
This evening, Steven Pinker, the Johnstone Family Professor in the Department of Psychology at Harvard University and author of several books including The Language Instinct, How the Mind Works, and The Blank Slate, moderates a discussion with two researchers who are exploring how the physiology of the brain gives rise to our experience of mind.
Rebecca Saxe is an assistant professor in the Department of Brain and Cognitive Sciences at MIT. She studies the neural and psychological basis of social cognition, the process through which we recognize and reason about other minds. Her goal is to understand how specific brain regions can give rise to the human ability to perceive causality, form beliefs, and build understanding based on prior events.
Bruce Lahn is a Howard Hughes Medical Institute investigator and a professor in the Department of Human Genetics at the University of Chicago. In his mammalian biology lab he is working to identify the genetic changes that occurred over evolutionary history that gave rise to the human brain. He has found that, on average, protein sequences of brain-related genes have evolved more rapidly in primates than in other mammals, and that this accelerated evolution is most dramatic in the lineage leading to humans. He also studies stem cell biology, particularly the question of what gives stem cells their "stemness."
Probing the Genetic Basis of Human Brain Evolution
Bruce Lahn, PhD
University of Chicago
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.