The generation of complexity in evolution: a thermodynamic and information-theoretical discussion.

It is argued that the evolutionary tendency toward complexity derives from the Second Law of thermodynamics and the set of physicochemical constraints provided by the biosphere. Complexity-generating processes provide the means by which thermodynamic information resulting from solar energy influxes can be dissipated. In particular, reductions in energetic information promote the growth of molecular size, and reductions in configurational information promote aperiodicity in molecular sequences. Natural selection converts the sequence entropy generated in these processes into molecular information.