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punctuated equilibria |
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punctuated equilibria (evolution) In the fossil record, long periods of little change in lineages interspersed with brief periods of relatively rapid change. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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Paleontologist Stephen Jay Gould's description of the evolutionary theory of punctuated equilibrium points out that geologically abrupt appearance and subsequent extended stasis of species is a fair description of evolutionary reality. While punctuated equilibrium (PE) reflected in the fossil record is a strong negative evidence to the underlying principle of phyletic gradualism (PG) enshrined in the evolutionary theory, the phenomenon of cell-directed mutagenesis challenges another tenet of the theory, namely, the requirement of stochastic mutations produced by extra-cellular agents to create heritable changes in the organism. Shermer begins by analyzing several heterodox theories--such as the punctuated equilibrium model of evolution offered by Niles Eldredge and Stephen Jay Gould, and the relationship between race and athletic achievement. |
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