Re: Evolution: A few questions

From: George Murphy <>
Date: Sun Jun 20 2004 - 13:57:01 EDT

> In contrast even to a benign remodel, let me note what happens during the
> metamorphosis of a frog. The embryo hatches and begins to grow as a
> purely aquatic form, breathing through gills. It strips algae off
> supports or consumes eggs or other tadpoles. With every original part
> fully functional, the tadpole sprouts legs, first rear, then front. Only
> when the legs are fully functional for swimming does the tail resorb.
> While the external changes are taking place, lungs are developing within.
> With the lungs fully developed, the gills are lost. But. at the same
> time, the small frog can "breathe" through its skin. Without impeding
> feeding, another change within produces a tongue capable of catching
> insects. The aquatic tadpole has become a frog capable of swimming in the
> water or hopping on land with no down time at all.

Dave, I don't know whether or not this argument is original with you. There
have, of course, been comparisons between evolution & embryological
development. But I haven't previously seen this argument for the usefulness
of "intermediate forms" & think it's excellent. In fact, it simply blows
away all the arguments to the effect that such intermediate forms muct have
been selected against in the evolutionary process. Of course I mean that as
a matter of general principle. Specific instances of development may still
provide difficulties.

Received on Sun Jun 20 14:16:07 2004

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