Evolutionary theory is experiencing a period of close scrutiny. Some authors assert that evolutionary theory is essentially complete (e.g. Charlesworth et al., 1982; Stebbins and Ayala, 1981; Buss, 1987), and others argue for a replacement theory that is independent of Darwinian principles. What is needed, however, are approaches that try to integrate traditional principles and research programs with new ideas that can address problems not addressed by current evolutionary theory. This is exemplified by the titles of recent texts and articles that emphasize the need to "expand" (Gould, 1980), "finish" (Eldredge, 1985), "extend" (Wicken, 1987), or "unify" (Brooks and Wiley, 1988; Brooks et al., 1989) evolutionary biology. Attempts to find common ground among these various proposals have begun (e.g. articles in Weber et al., 1988). To my mind, two concepts are common to all these proposals. The first is the feeling that there is more to evolution than changes in gene frequencies in local populations under different environmental conditions. The second is that evolutionary theory has been preoccupied with questions of maintenance rather than with questions of origin of diversity.