Richard C. Lewontin, the geneticist whose research contributed to a revolution in population biology by showing that enormous genetic variation exists within each species, will give three public lectures at the University of California, Davis, beginning Monday, Nov. 18. A Harvard University professor, Lewontin contributed a fundamental observation and measurement technique that allowed scientists to make predictions based on Darwin's theory of natural selection, which assumes there are genetic variations that can be passed along through generations. Lewontin found more variations than anyone had anticipated. His findings apply to all organisms, from bacteria to animals and from molds to plants. Lewontin is an Alexander Agassiz Professor of Zoology in the Museum of Comparative Zoology at Harvard University and a professor of population sciences at the Harvard School of Public Health. Below is a schedule of his lectures, which are sponsored by the campus Division of Biological Sciences and supported through the endowed Tracy and Ruth Storer Lectureship in the Life Sciences. • "What's Wrong With Evolutionary Explanations?" Monday, Nov. 18, 4:10 p.m., in 180 Med Sci Bldg. C. • "Patterns of Constraint on Genes and Proteins," Wednesday, Nov. 20, 4:10 p.m., in 180 Med Sci Bldg. C. • "Distinguishing History From Natural Selection," Thursday, Nov. 21, 8 p.m., in 180 Med Sci Bldg. C. Lewontin will discuss how studies of genetic variation can shed more light both on evolutionary forces and on the root causes of genetic variations. "The central issue in evolutionary genetics is to distinguish different forces that govern evolution," Lewontin says. "The story of evolution is not just the story of natural selection. A lot of evolution is just historical accident." Lewontin studies DNA sequences at the molecular level to distinguish those forces. He began his population studies as a doctoral student at Columbia University, where he studied how genetic differences between organisms were manifested in different environments. "That work and everything I have learned since has taught me that the organism is not determined by its genes, although its different traits are undoubtedly influenced to varying degrees by its genetic constitution," Lewontin says. Established in 1960, the Tracy and Ruth Storer Lectureship in the Life Sciences brings eminent biologists from other institutions to participate in the UC Davis academic community.