We have explored the evolution of cooperation and conflict at several different levels, including replicating molecules within networks of molecules, cells within organisms, and among organisms within societies. We have been especially interested in developing a general theoretical framework within which the evolution of cooperation at different levels can be understood. How this came about is far from clear. The evolution of multicellular organisms is probably the premier example of the integration of lower evolutionary levels into a single, higher-level individual. Explaining the transition from single cells to multicellular organisms is a challenge for evolutionary theory.
Current work focuses on including epigenetic change during development.
Evolutionary Transitions in Fitness and Individuality . While accepting the importance of variability in the evolutionary process and the role of sex in creating variation, my research has led me to explore alternative explanations for the ubiquity of sex, especially the role of sex in coping with genetic error. The most obvious consequences of sex are its risks and costs. I believe that individuals would not undertake such an inherently risky and costly process as sex, unless they were in trouble to begin with. Genetic error, both mutation and damage are a constant threat to the integrity of the organism and the vitality of life.