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December 26, 2006
This picks up on this post here, which mentions Elizabeth Grosz's recent collection of essays entitled Time Travels: Feminism, Nature, Power I want pick up on Grosz's argument about postructuralism's presupposition about nature: it is static and fixed, with all change and movement coming from culture. A passive nature is what is transformed and dynamized by culture. One of the odd aspects of poststructuralism is that it had little to do with the biological sciences. Somehow the focus on deconstructing the liberal subject, or the turn to embodied subjectivity, never placed the human beings within nature as understood by the biological sciences. It was almost as if human beings were inside culture and society but outside nature.
Rarely, if ever, was there an engagement with the current conception of evolutionary theory that emerged from the 1920s to the 1940s, when geneticists, mathematicians, naturalists, and paleontologists reached a consensus on how evolution works. Called the Modern Synthesis, the theory merged the 19th-century botanist Gregor Johann Mendel's discoveries of inheritance patterns with Darwin's ideas of evolution by natural selection. At its core, the Modern Synthesis holds that microevolution -- the minor changes at the level of each individual -- can explain the broad patterns in the history of life, also known as macroevolution.
What of Gould and Eldredge's idea of punctuated equilibrium? This is evolution by jerks. It interprets the fossil evidence as suggesting that evolution worked in terms of species remained essentially unchanged for millions of years, and then disappeared abruptly, only to be replaced, in a blink of geologic time, by markedly new species.
Gould and Eldredge's implication they two drew from their findings is that punctuated equilibrium suggests a different style of evolution, in which species, not just individuals, competed against one another for survival -- a concept dubbed "species selection."
What of evidence that life on earth occasionally suffers instantaneous catastrophes that temporarily shatter the rules of gradual Darwinian evolution, he says. Mammals replaced the dinosaurs not because the latter were ill-adapted to their environment but because they were wiped out by a gigantic asteroid impact. Such calamities make it impossible to extrapolate the big changes in evolution from the kind of small-scale, microevolutionary steps visible at any moment in time.
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