Extinction from RE: Old-Earth Creationism

From: bivalve (bivalve@mail.davidson.alumlink.com)
Date: Tue Feb 19 2002 - 15:05:51 EST

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    >Is extinction a scientific concept? I thought, at least under
    Punk Eek, that a species just sort of fade until they are
    resurrected into new forms, such as dinosaurs --> birds.<

    No, punctuated equilibrium claims that species change
    little for long periods of time and then rapidly either go
    extinct or evolve into new species. Whether or not the
    resulting for is a new species depends on the definition.

    You are probably thinking of a slightly different issue.
    Some advocates of a phylogentic species concept might
    claim that either a species goes extinct entirely or else it
    gives rise to two descendant species and the original
    species becomes extinct. The fact that a descendant form
    may be very different from the ancestor is ignored if no
    other branches have arisen. For example, if you lump all
    early Homo as Homo habilis, all intermediate Homo as H.
    erectus, and all modern-looking ones as H. sapiens,
    believing the course of evolution to have been roughly
    linear through these, then the advocate of this view would
    claim that you should call them all Homo sapiens because
    no branches have arisen, despite the many differences in
    The polar bear arose from the brown bear in the past few
    hundred thousand years or so. Modern brown bears seem
    unchanged from the fossil brown bears before the split, yet
    extreme advocates of this view would claim that either the
    modern brown bears are a separate species from the
    ancestral brown bears or else that the polar bear should
    not be considered a separate species, even though it is so
    morphologically specialized that it once was given its own

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