Published online by Cambridge University Press: 17 July 2017
G. Udny Yule (1924) was perhaps the first to examine the subject of rates of taxonomic evolution mathematically, but George Gaylord Simpson was the first to examine the subject from within the confines of the so-called Modern Synthesis of Biology (Simpson, 1944). In that sense, therefore, Simpson's can be regarded as the first modern study of rates of taxonomic evolution. Although he is almost universally regarded as the catalyst behind the current interest in taxonomic evolutionary rates, it is a remarkable fact that Simpson's aims were almost entirely different from those of current workers. In a very important sense, Simpson's taxonomic rates of evolution were not taxonomic at all, but were morphological, or even more to the point, genetic.