From: Cliff Lundberg <cliff@cab.com>
>Richard Wein wrote:
>
>>>>You're still evading my question of whether we ever see heritable
>>>>Siamese-twinning in humans. If not, then your claim that we see this
>>>>mechanism in humans is false.
>
>This is a triviality to the theory in question, something I would happily
>scratch from the article if I were convinced you were right about this rare
>phenomenon. The big point is simply that Siamese-twinning is a mechanism
>for generating morphological complexity, a mechanism that we can
understand.
I'm not clear what you mean by this.
Are you withdrawing your claim that the mechanism underlying your
theory (heritable Siamese-twinning) is observed in humans?
Or are you saying that heritability of Siamese-Twinning is unimportant to
your theory?
>>And I come back to the point that I made earlier. Partial Siamese twinning
>>shows that a simple chance disruption during development can result in
>>functional duplicate limbs and organs, even in an organism as complex as a
>>human. If this can happen when the disruption is by chance, why can't it
>>also happen when the disruption is due to a simple mutation?
>
>Duplicate limbs and groups of organs, fine. Gradual serial accretion of new
>segments within sets of homologs, no way.
This seems to be a substantial concession, so let me make sure I understand
you. Do you now agree that limbs and organs may be duplicated as the result
of a simple mutation, i.e. not necessarily due to reactivation of an
atavistic gene?
If you now agree with this, then much of our discussion, such as polydactyly
in humans, loses its relevance. So I'll wait for your reply before
continuing.
Richard Wein (Tich)
This archive was generated by hypermail 2b29 : Tue Jun 20 2000 - 09:11:46 EDT