Macro- and microevolution [was: Re: Icons of Evolution]

From: Paul Nelson (
Date: Fri Jun 15 2001 - 10:32:09 EDT

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    Allan Harvey, responding to Todd Greene, wrote:

    >> What is it about "macroevolution," what are the
    >> characteristics of this evolution that are the cause
    >> for raising some kind of distinction from
    >>"microevolution"? Is this a distinctive kind
    >> of evolution recognized through scientific
    >> observation? Or is this concept something in
    >> the eye of the creationist beholder?
    > Somebody, I think on this list, once remarked that
    > "microevolution" is usually effectively defined as
    > "evolution I believe in" while "macroevolution" means
    > "evolution I don't believe in." I too would like to
    > see anti-evolutionists give the terms scientific
    > definitions and use them consistently. I'm not
    > holding my breath.

    The terms "microevolution" and "macroevolution" were
    coined by Russian evolutionary geneticists in the late
    1920s, and were already common parlance in the
    evolutionary literature by the mid 1930s. See, for
    instance, the introduction to Dobzhansky's _Genetics
    and the Origin of Species_, where he describes the
    "reluctant sign of equality" that biologists have placed
    between micro- and macroevolution:

    "...there is no way toward an understanding of the
    mechanisms of macro-evolutionary changes, which
    require time on a geological scale, other than through
    a full comprehension of the microevolutionary processes
    observable within the span of a human lifetime and
    often controlled by man's will. For this reason we
    are compelled at the present level of knowledge
    reluctantly to put a sign of equality between the
    mechanisms of macro- and micro-evolution, and,
    preceeding on this assumption, to push our investigations
    as far ahead as this working hypothesis will permit."

    (T. Dobzhansky, _Genetics and the Origin of Species_
    [New York: Columbia University Press, 1937], p. 22)

    A "working hypothesis" can fail under contrary evidence,
    of course, and today many evolutionary theorists argue
    that there is in fact an inequality between micro- and macro-
    evolution. See, for instance, this recent paper by
    paleontologist Douglas Erwin:

    Douglas H. Erwin
    Department of Paleobiology
    National Museum of Natural History
    Washington DC 20560

    "Macroevolution is more than repeated rounds of microevolution"

    _Evolution & Development_ 2 (2000):78-84

    SUMMARY [Erwin's abstract]: Arguments over macroevolution versus
    microevolution have waxed and waned through most of the twentieth
    century. Initially, paleontologists and other evolutionary biologists
    advanced a variety of non-Darwinian evolutionary processes as
    explanations for patterns found in the fossil record, emphasizing
    macroevolution as a source of morphological novelty. Later,
    paleontologists, from Simpson to Gould, Stanley, and others,
    accepted the primacy of natural selection but argued that rapid
    speciation produced a discontinuity between micro- and
    macroevolution. This second phase emphasizes the sorting of
    innovations between species. Other discontinuities appear in
    the persistence of trends (differential success of species within
    clades), including species sorting, in the differential success of
    clades and in the origination and establishment of evolutionary
    novelties. These discontinuities impose a hierarchical structure to
    evolution and discredit any smooth extrapolation from allelic
    substitution to large-scale evolutionary patterns. Recent
    developments in comparative developmental biology suggest
    a need to reconsider the possibility that some macroevolutionary
    discontinuities may be associated with the origination of
    evolutionary innovation. The attractiveness of macroevolution
    reflects the exhaustive documentation of large-scale patterns
    which reveal a richness to evolution unexplained by microevolution.
    If the goal of evolutionary biology is to understand the history of
    life, rather than simply document experimental analysis of evolution,
    studies from paleontology, phylogenetics, developmental biology,
    and other fields demand the deeper view provided by macroevolution.

    [end abstract]

    In short, the distinction between micro- and macroevolution was
    formulated by evolutionary biologists (not creationists or design
    theorists), and remains a topic of active research and debate
    within evolutionary theory.

    Paul Nelson
    Senior Fellow
    The Discovery Institute

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