Mendel's Legacy: The Origin of Classical Genetics

This book is a labor of love by a professional geneticist with a sharp intellect and a mature understanding of society as well as science. The book is beautifully produced, with many diagrams and portraits of the scientists, as well as photographed excerpts from famous papers (although there are no color plates). Perhaps the most attractive aspect of Carlson's approach is the care with which he presents the evidence for specific genetic principles, and the arguments used by opponents of what are now elementary textbook principles. Appreciating basic genetic principles is much enhanced by realizing the intellectual struggle involved in each piece of the puzzle. For instance, I have read a dozen times that quantitative geneticists rejected Mendelism because they believed in evolution by continuous, incremental change, whereas Mendel's laws appear to support discontinuous, saltationist, change. I always thought this to be a quite silly objection, and that R. A. Fisher's demonstration of the compatibility of the two views was stating the obvious. Carlson suggests a far deeper objection. Following Galton, quantitative geneticists believed in regression to the mean and blending inheritance, both seeming incompatible with Mendelism. Overcoming these objections is quite a sophisticated task. In another passage, Carlson presents Sewall Wright's reasons for developing his position on gene interaction and environmental effects on natural selection, based on his study of coat color in guinea pigs. Again, he shows that opposition to Mendelian segregation was not just conservative stubbornness, but rather a reaction to the fact that a considerable fraction of inheritance studies did not conform to Mendelian segregation. We now know why, with our understanding of transpositions, gene jumping, and the like. The glory of this book is simply reading the detailed history of marvelous discoveries in an almost blow-by-blow fashion. But, almost as welcome is Carlson's historical method, which he presents briefly at the end of the book. Science, he says, is the "winning of the facts." I interpret this to mean that truth needs no explanation---it is its own justification. "I have read accounts" Carlson says (p. 208) "...that attempted to explain science in sociological (in-groups versus outsiders), political (Marxism versus capitalism), or historical (depression, war, and ideology) contexts, and I found these either false or extraneous." This viewpoint is such a breath of fresh air after plowing through so many insufferable post-modern treatments of science. Carlson does have strong and interesting arguments concerning the time and place of scientific discoveries. He notes that genetics was a European stronghold in the Nineteenth century and became an American-led endeavor in the classical period from 1900 to 1930. He attributes this to the scientific freedom offered by the American graduate school, among other things. Hitler and Stalin account for the continued pro