On Wed, 29 Nov 1995, Jim Foley wrote:
>
> Let's break that into two separate items. I don't have any problem
> thinking that unneeded teeth could degenerate and eventually disappear.
> That would be consistent with the experiments that have been done which
> show that chickens still have the genes for teeth, they're just not
> expressed.
This is the Fisher & Kollar experiment, and it continues to generate
debate in "tooth" circles. Of interest, though, is that the enamel gene
(amelogenin) has not been found in the chicken as would be expected. So
the question is: "What exactly was the epithelial product produced by the
chick epithelium in the recombination experiment?" Some think is was
enamel, but from murine epithelial contamination.
Literature you might be interested in:
Fisher & Kollar (1980) Science vol 207: 993.
Lygnstadaas SP (1990) J of Comp Phys - B, vol 160(5): 469. On the enamel
gene.
Similarly, fossil platypuses have teeth, whereas modern ones
> have them only in the embryo stages. I have seen creationists argue
> that this is degeneration and could happen naturally, so the same
> argument could equally well explain the loss of teeth in birds.
Totally agree. Anodontia (lack of teeth) in humans is common with
epithelial genetic conditions. It just requires knocking out an
initiatory pathway.
Cordially,
Denis
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Denis O. Lamoureux DDS PhD PhD (cand)
Department of Oral Biology Residence:
Faculty of Dentistry # 1908
University of Alberta 8515-112 Street
Edmonton, Alberta Edmonton, Alberta
T6G 2N8 T6G 1K7
CANADA CANADA
Lab: (403) 492-1354
Residence: (403) 439-2648
Dental Office: (403) 425-4000
E-mail: dlamoure@gpu.srv.ualberta.ca
"In all debates, let truth be thy aim, and endeavor to gain
rather than expose thy opponent."
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