In Memoriam: Robert R. Sokal (1926–2012)

Abstract

Robert R. Sokal, Distinguished Professor Emeritus in the Department of Ecology and Evolution at the State University of New York at Stony Brook, Long Island, New York, died on 9 April 2012, at the age of 86 years. It is particularly appropriate that he be remembered in this Journal, for his first academic position, in which he developed one of the fields for which he is best known, was in the Department of Entomology, University of Kansas. Throughout his career he was involved in the development and use of a wide variety of statistical methods for evaluating similarities among organisms (hence numerical taxonomy) and for analyzing spatially distributed variations such as patterns in human genetic and linguistic data. He published widely in these fields and is probably most widely known for his book (coauthored with F. James Rohlf), Biometry, which has influenced the training and practice of many biologists, especially in fields of evolution, ecology, and anthropology. Born in Vienna, Austria (13 January 1926), he left there in 1939 with his family at the same time as many other European Jews, to escape the Nazi regime. By way of train to Italy and by ship to China, they settled in Shanghai where he continued schooling. From St.John’s University in Shanghai he received a bachelor’s degree (biology) in 1947. There also he met Julie Chenchu Yang who played an important role throughout his subsequent life. At St.John’s he wrote for publication his first scientific paper, a study of the head morphology of a dragonfly. In the same year, 1947, he entered the University of Chicago as a graduate student, and in 1948 he and Julie were married. At Chicago he worked under the direction of Alfred E. Emerson (ecologist and termite specialist) and Sewall Wright (population biologist). His dissertation was a statistical treatment of the geographical variation in morphology of a poplar gall aphid, Pemphigus populitransversus, for which he received a Ph.D. degree in 1952. At that time he moved to the Department of Entomology at the University of Kansas, first as an Instructor, then in the usual academic sequence. His first study at Kansas had to do with the evolution of insect behavior and of insect resistance to insecticides. Specifically, he asked if Drosophila melanogaster, so well known genetically, would develop insecticide resistance as do many insect pests, and if so, what could be learned about the genetics and evolution of such resistance. He reared Drosophila larvae in food medium containing DDT at levels that killed some of the larvae. After several generations with larvae in this environment, mature larvae were leaving the food and pupating on the glass walls of the food containers. Thus behavior had evolved, and apparently as a result, some change in resistance by larvae to DDT in their environment. Later, Sokal began a study for which he is well known, concerning classification of organisms. Traditionally classifications had been based on subjectively determined phylogenetic ideas, the views of specialists, Sokal said by intuition. When different