Page 123 - The Errors the American National Academy of Sciences

The NAS's Errors in Portraying Common
Structures as Evidence of Evolution

structure emerges in very different ways in a great many different
creatures. For example, the alimentary canal in sharks forms from the
roof of the embryonic gut cavity. In the lamprey, an eel-like fish, how-

ever, it forms from the floor of the gut. In frogs, it begins to form from
the floor and roof of the embryo, while in birds and reptiles it starts in
the lower layer of the embryonic disc or blastoderm. 19
Darwin's classic example of homology was the forelimbs of ver-
tebrates. This, too, represents a problem for the theory of evolution.
This is because the forelimbs emerge in different body segments in
different species. In the newt, for example, the forelimbs emerge from

segments 2, 3, 4, and 5 of the trunk; in lizards, from segments 6, 7, 8,
and 9; and in human beings, from segments 13, 14, 15, 16, 17, and
20
18. As the molecular biologist Michael Denton has stated, it could be
concluded from this fact that forelimbs are not homologous. 21
According to Denton,

The development of the vertebrate kidney appears to provide an-
other challenge to the assumption that homologous or-
gans are generated from homologous embryonic
tissue. In fish and amphibia the kidney is derived di-

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