(CIT): Evolutionary biology's central task is to provide historical explanations for the diversity of living forms. At the molecular level, the question is how genes, and the proteins they code for, acquired their functions. By combining evolutionary and phylogenetic analysis with molecular and structural biology, Dr. Thornton has shown, atom by atom, how a biomedically crucial family of proteins -- the steroid hormone receptors -- changed over hundreds of millions of years to acquire their present-day functions. Lecture series presented by National Institute of General Medical Sciences, the Office of Science Education, and the National Human Genome Research Institute. For more information, visit