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Re: Evolution, "adaptation", and what's currently adaptive
Heiko Pawelczyk (weizenkeim@t-online.de)
15 Sep 1996 16:10:10 GMT
In article <lpiotrow.444.323712E3@magnus.acs.ohio-state.edu>,
lpiotrow@magnus.acs.ohio-state.edu (Len Piotrowski) writes:
>In article <512lgo$38ga@argo.unm.edu> mycol1@unm.edu (Bryant) writes:
>
[snip]
>
>organisms lose their eyes. This, says Bryant, is a testable hypothesis in the
>parasitology literature. Lets see: would a higher degree of eye assaults in
>eyeful cave organisms versus eyeless cave organisms be sufficient proof of
>this need to unevolve the eye trait? Or would a higher incident of eye
>assaults in eyeful and eyeless cave dweller compared to eyeful and eyeless
>non-cave dwellers be convincing? Even if the data display a bimodal
>distribution, can there be an overall high incidence of assaults in cave
>environments untestable by the parasitology literature? At what point can we
>identify these kinds of stories as just so without fear of being labelled
>ourselves as anti-science?
>
>Cheers.
>
>--Lenny__
>
>"If you can't remember what mnemonic means, you've got a problem."
> - perlstyle
As biologist I have learnt that any gene, even that ones responsible
for eye formation are subject to mutations. Organisms living in a
lightless environment, therfore not needing their eyes anymore, are
not impeded by reduced capabilities of their eyes. Hence there is no
selection against these mutations and they begin to gather until the
eye is more or less reduced.
Since there are cave dwellers who stay there only part of their life
and spent the other outside, these should be blind too, if that
hypothesis of an increased incidence of injury where true. But this is
not the case. In the third world there is a high incidence of
blindness caused by freshwater born parasites. The humans living there
are not generally blind.
--
Heiko Pawelczyk
email weizenkeim@t-online.de
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