Gradualism in Evolution (was Categories ...) (Agnosticism)

by George Jelliss , Crewe, Saturday, July 10, 2010, 12:24 (5031 days ago) @ dhw

dhw: "Either innovations work or they don't, and if they do, they are already complex, even if they survive and later become even more complex. It therefore seems to me that evolution doesn't depend on gradualism at all. Perhaps someone can enlighten me."-There is a section in Ernst Mayr's "What Evolution Is" that deals with this subject, though as I've said before I'm not a biologist and I find the language difficult to follow. He points out that: "individuals in a single population may differ by visibly different characters" (he cites eye colour and number of molars). He continues: "A successful mutation with a large phenotypic effect can be gradually incorporated into a population as long as it is able to pass through a period of polymorphism in which it coexists with the previous phenotype, until it has completely displaced the original gene." He ends with "it must be remembered that there is a considerable range in the size of the mutations that lead to evolutionary change". Later on he says: "Darwinian gradualism is due to the gradual restructuring of populations."

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GPJ