Population Genetics, Genetic Variation, and the Monomorphism of the Human Species

This talk will relate discussions about human genetic variation (a key issue in the debates on human races) to the history of theoretical population genetics. In the first part of the presentation, I will analyse how two prominent statistical population geneticists, namely Newton Morton and Masatoshi Nei, used the concept of race in a series of studies that took place from the late 1950s to the late 1980s. I will argue that a proper understanding of these lines of work requires considering more general debates on population genetics theory, such as the classical-balance debate, and the debate on the neutral theory of molecular evolution. In the second part of the presentation, I will move away from the focus on variability and consider the issue of genetic monomorphism. Although the science of population genetics has been typically concerned with the study of genetic variability, not all genes present variation. An interesting outcome of molecular studies of human variation has been to show that the proportion of polymorphic loci may be minute, with current estimates suggesting that humans rank among the most monomorphic species. My purpose will be to reconstruct how geneticists came to view humans as genetically monomorphic, and to assess its implications from the viewpoint of population genetics theory.