[T]ransitions are often found in the fossil record. Preserved transitions are not common -- and should not be, according to our understanding of evolution (see next section) but they are not entirely wanting, as creationists often claim. [He then discusses two examples: therapsid intermediaries between reptiles and mammals, and the half-dozen human species - found as of 1981 - that appear in an unbroken temporal sequence of progressively more modern features.]


Faced with these facts of evolution and the philosophical bankruptcy of their own position, creationists rely upon distortion and innuendo to buttress their rhetorical claim. If I sound sharp or bitter, indeed I am -- for I have become a major target of these practices.


I count myself among the evolutionists who argue for a jerky, or episodic, rather than a smoothly gradual, pace of change. In 1972 my colleague Niles Eldredge and I developed the theory of punctuated equilibrium. We argued that two outstanding facts of the fossil record -- geologically "sudden" origin of new species and failure to change thereafter (stasis) -- reflect the predictions of evolutionary theory, not the imperfections of the fossil record. In most theories, small isolated populations are the source of new species, and the process of speciation takes thousands or tens of thousands of years. This amount of time, so long when measured against our lives, is a geological microsecond . . .


Since we proposed punctuated equilibria to explain trends, it is infuriating to be quoted again and again by creationists -- whether through design or stupidity, I do not know -- as admitting that the fossil record includes no transitional forms. Transitional forms are generally lacking at the species level, but they are abundant between larger groups.




アーカイブ ヘルプ
ログイン ユーザー登録
ようこそ ゲスト さん