The second law of thermodynamics poses a problem for evolutionary biologists. While it seems to predict increasing disorder over time, the record of evolution suggests ever-increasing order and higher levels of organization. The common solution to the paradox was to look for a balance between organic systems and their environment. Perhaps there was, as Schrodinger suggested, a trade-off by which organisms grew more orderly at the expense of the universe.

As with many paradoxes, the best approach may be to confront it head-on, which is what Brooks and Wiley have done, by putting forward the theory that evolution is actually a biological operation of the second law. In their view, entropy is not merely a tendency to disorder but the characteristic of all “time-dependent behavior.” The growth and development of an organism and the evolution of the species become more a matter of irreversible history than of mere survival of the fittest. The history of a species, therefore, significantly determines its “future trajectories.” Successful species are not necessarily those which adapt best to their environment. Indeed, the authors speak of “the survival of the adequate,” because evolution is a process “historically restrained . . . regardless of the environment.”

One intended benefit of this theory is to reconcile the conflict between strict neo-Darwinists, for whom reproductive competition is the sole determining factor, and the believers in orthogenesis, the notion that evolutionary changes have a purpose or direction. For Brooks and Wiley, there is obviously no purpose, no Aristotelian telos toward which life is tending; however, there is a historically determined process of development which stipulates that the longer a genealogical population (e.g., a species) persists, the more self-organized it becomes. Such a process is obviously constrained by environmental factors, but they alone do not determine the direction of change.

Evolution as Entropy is not for the casual reader, even one with a Ph.D. in zoology. It is a densely argued patchwork of speculation and journal articles that will perplex even its authors a dozen years hence. They have been generous, though, with prelude and reprise as well as chapter summaries, but in these sections too they cannot resist entering into learned quarrels. This is all the more the pity, since they think clearly and write, for scientists, that is, effectively.

In any event, it is a bold work—explicitly Aristotelian, and, despite a sappy concluding paragraph (“We would like nothing better than to make sure that violent human behavior could no longer be justified and condoned as an unalterable consequence of an evolutionary legacy” [how glibly they slip from is to ought!]), it deserves attention from anyone who believes that biological theory can be used in an account of human behavior.


[Evolution as Entropy: Toward a Unified Theory of Biology, by Daniel R. Brooks and E.O. Wiley; Chicago: University of Chicago Press]