2005-01-24

Punctuated Equilibria

It's explained here:The Panda's Thumb: Time: Stealth Attack On Evolution
“By the 1950’s, biologists had synthesized Darwin’s natural selection and Mendel’s genetics into the discipline of population genetics, the mathematical theory describing how genes spread through populations under the influence of natural selection. A direct deduction from population genetics is that small populations can evolve more rapidly than large populations. In 1972, Gould and Eldredge applied this result from population genetics to the fossil record, producing the model of 'punctuated equilibria.' They argued that the fossil record would most commonly record only widespread species, and that these would typically evolve slowly. New species (closely related to the old species) would tend to evolve in small, isolated populations, and then spread. They would therefore appear 'suddenly', geologically speaking, in transitions taking between 10,000-1,000,000 years. Punctuated equilibria therefore predicts that gradual species-species transitions would tend to be relatively rare in the fossil record. It specifically did not say that 'transitional fossils' in general are absent — Gould, annoyed at creationist misrepresentations of his position, specifically said in rebuttal, 'Transitional forms are generally lacking at the species level, but they are abundant between larger groups.'"

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