Eight Little Piggies (Book review)

Eight Little Piggies S.J. Gould, 1993. Collection of Gould's essays in Nature since last book. As good as ever, but somewhat repetitious in his concerns, naturally. He seems unaware of complexity theory (CT), which amongst other things suggests that evolution must be "punctuated." CT holds that a complex system can exist in limited number of states. Change from one state to another may be very rapid, catastrophic even. Thus, if an organism is a complex system, then its form (genome or phenotype) has a limited number of stable states. Thus, selective pressure (or genetic drift?) would shift the form from one stable state to another very quickly. Intermediate forms are not stable, and therefore could not exist for very long. Anyhow, Gould's emphasis on non-Darwinian mechanism and processes in evolution solves a number of puzzles.
     The most moving essay tells of the snails in Tahiti, which have disappeared since a British scientist spent his whole life describing them as a base-line for future study of evolutionary changes. Makes you wanna cry. (August 1994)
     Comment 2012: I realised some time ago that the Gould-Eldridge hypothesis of punctuated equilibrium is Darwinian to its core: when an environment changes very slowly, there is little selective advantage in the vast majority of changes, so that selective pressure operates against change. Thus the equilibrium, a time of very slow evolution, driven almost entirely by genetic drift. Evolution is the effect of selective pressure on the genome. Natural selection will operate to drive rapid change when the environment changes rapidly, and to conserve existing genotypes when the environment changes slowly. The question then becomes, How rapidly must the environment change to promote rapid evolution? The answer, I think, is a function of the generational die-off rate of any given population of organisms. If the die-off is too high, the organism will become doubly extinct: it will cease to exist, and it will have no progeny.