Page 122 - The Evolution Impasse 1

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nists had to suppose another transitional Evolutionary mecha-
form between them. However, no skele- nisms
ton belonging to this theoretical transiti-
The neo-Darwinist model we refer to
on between Eusthenopteron foordi and
today as the theory of evolution propo-
the tailed water frog Icthyostega has
ses two basic evolutionary mechanisms;
ever been found.
natural selection and mutation. Accor-
Now, the two favorite subjects for
ding to the theory’s basic proposition,
most of the contemporary evolutionary
these two mechanisms are mutually
scenarios regarding tetrapod origins are
complementary. The source of evolutio-
Eusthenopteron (an extinct fish) and
nary changes is random mutations in the
Acanthostega (an extinct amphibian). Ro-
genetic structure of living things. Again
bert Carroll, in his Patterns and Proces-
according to the theory, natural selection
ses of Vertebrate Evolution, makes com-
favors the most advantageous characte-
ments on these allegedly related forms:
ristics caused by mutations, and thus li-
Eusthenopteron and Acanthostega
ving things evolve.
may be taken as the end points in the
However, these proposed mecha-
transition between fish and amphibians.
nisms actually have no evolutionary for-
Of 145 anatomical features that could be
ce at all. And there is no question of
compared between these two genera, 91
them giving rise to new species, as evo-
showed changes associated with adapta-
lutionists claim. (See Natural selection
tion to life on land . . . This is far more
and Mutation.)
than the number of changes that occur-
red in any one of the transitions invol-
ving the origin of the fifteen major gro-
ups of Paleozoic tetrapods. 154

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