Re: Cnidaria versus ctenophora

Now, Ben and Lorentz, the two of you seem to disagree with whether
symmetry-breaking took place-or perhaps the kind of symmetry-
breaking. This is actually good, for it gives us something to talk
about, discuss, and possibly debate.

Ben (post 7): "Now one major conjecture in the literature is that
nervous system evolution is heavily inter-twined with a process of
'symmetry-breaking' (to do with body-plan symmetry).
The hydra for example is regarded as having the most primitive-like
nervous system and also the most -primitive like (radial) symmetry."

Lorentz (post 10): "All evolution has to do to get from D_2 to C_2 is
add some feature that breaks the C_2 symmetry. Some biologists
apparently think that happened in the case of the ctenophore ancestor,
resulting in a
bilateral clade. This is probably wrong."

Now, one thing that has long interested me is the debate between Gould
and Dawkins regarding punctuated equilibrium.

(And the Cambrian Explosion certainly seems to me to be a big
punctuation mark!)

-Doug


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