Our understanding of life is being transformed by the realization that evolution occurs not only among individuals within populations, but also through the integration of groups of individuals into new higher-level individuals. Indeed, the major landmarks in the diversification of life and the hierarchical organization of the living world are consequences of a series of evolutionary transitions in individuality: from genes to gene networks to the first cell, from prokaryotic to eukaryotic cells, from cells to multicellular organisms, from asexual to sexual populations, and from solitary to social organisms. We are interested in understanding the diversity of life by understanding the evolution of interactions among individuals and how these interactions may create new kinds of evolutionary individuals. We are especially interested in cooperation and conflict during the origin of multicellularity and the evolution of sex. We are interested in the consequences of sex in terms of coping with genetic error (mutation and damage), and how sex affects evolutionary transitions in individuality. The methods used in our work involve mathematical and computer models, experiments with micro-organisms, bioinformatics, comparative genomics, molecular biology, and philosophical analysis. Our ongoing work concerns the evolution of cooperation, sex, multicellularity and complexity in volvocine green algae. We are grateful for past support from the National Science Foundation and the National Institute of Health, and to NASA Exobiology and the National Science Foundation for our current support.
