Thermodynamics and the conceptual structure of evolutionary theory.

Thermodynamics and evolutionary theory have spent most of their shared history in adversarial relationship to one another. The point of this paper is to consider some qualitative ways in which thermodynamics can enrich both the theory and epistemology of evolution. The "autonomy of biology" posture in evolutionary theory hangs on the supposed uniqueness of why-questions in biology. With this posture, and with the general obstruction of constructive dialogue between evolution and the physical sciences it fosters, come the perennial accusations that Darwinism deals in adaptational teleology but not mechanisms. Thermodynamics provides for a two-tiered hierarchy of causation in nature in which the why-question is rendered not only legitimate materialistically, but essential to understanding the evolutionary process in its totality--from the emergence of life to the branching of lineages in speciation.