Abstract

A lesson in evolutionary theory can be drawn from the work of Rick Charnov, who transformed Fisher’s sex ratio theory into sex allocation theory, but unfortunately, the lesson has not spread far enough. The lesson is that costs as well as frequencies need to be included. That is so whether we are talking about evolutionary ecology (e.g., density dependence), social evolution (e.g., sexual selection), origins, an extended evolutionary synthesis, multilevel selection, or whatever. The two dimensions can be expressed in a variety of ways—investing as well as spending, quality as well as quantity, costs as well as frequencies, and somatic as well as reproductive functions, for example. Both are needed everywhere in evolutionary theory.