A naive observer, studying the homages to Darwin written during the bicentennial year of 2009, might wonder why evolutionary biologists even bother coming to work every day, knowing that the last great insight into evolution happened 150 years ago. In reality, in spite of the cultural imperative to label everything "Darwinian", evolutionary thinking has been undergoing a slow and uncertain revolution ever since the discovery of genetics, from Darwin's view of evolution as a process of shifting plastic forms via abundant infinitesimal variation, in response to external demands, to a more open-ended process of mutational exploration of fitness landscapes.  

The latter view has many implications.  Some of these implications are mundane or familiar, e.g., it has become commonplace to say that evolution is "contingent" because the outcome of evolution may depend on which mutations occur.  Other implications are more radical and disconcerting, therefore of greater theoretical interest.  Among these radical implications are ideas that used to be ridiculed, like the idea that mutation can be a source of direction or orientation in evolution. The ability to demonstrate something that used to be ridiculed as a heresy would be a clear indication of the need for a shift in understanding.  

Indeed, biases in mutation (e.g., see bubble plot of mutation rates at right) bias the course of evolution, even adaptive evolution (see Rokyta, et al.), in a predictable manner. This causal influence raises many questions: What is the population-genetic mechanism (see Yampolsky and Stoltzfus, 2001)? How did neo-Darwinists overlook this mechanism, claiming instead that internal causes of direction are impossible (Stoltfus, 2006a)? Can we tease apart mutational effects from fitness effects? (Yampolsky and Stoltzfus, 2005) What kinds of mutation biases exist and what is their impact? Can they cause long-term patterns or trends (Stoltzfus, 2006b)? How often are mutational effects wrongly attributed to "function"? What about developmental biases in phenotypic variation (Stoltzfus, 2006a)? Our research in this vital and exciting area includes both theoretical modeling and data analysis. Ongoing work addresses the alleged adaptedness of the genetic code (Stoltzfus and Yampolsky, accepted), and the challenges for genomics (Stoltzfus, in prep).