Re: Origin of feathers

[Thom Quinn <swo@execpc.com>]

I have posted a transcript of the talk I gave at Dinofest, The
informational origin of feathers: an overveiw, on the web.

I have not linked any pictures as of yet, but I plan to do so when I
have the time.

It can be found at http://www.evolutionary.org/talk.htm

Comments are welcome, please send them privately to me.

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Tony Canning wrote:
> 
> On Apr 9, 11:46am, Dinogeorge wrote:
> 
> > When pre-feathers first appeared, it is likely (though not certain, of
> course:
> > perhaps they popped into existence fully structured, with rachis, barbs, and
> > barbules!) they were small (like hairs) and thus had little impact on the
> > visual appearance of the animals. The visual impact would have come later,
> and
> > would have gone hand-in-hand with the enlargement and elaboration of the 
> > pre-
> > feathers.
> >-- End of excerpt from Dinogeorge
> 
> Well, I suspect vertebrates with good vision are very sensitive to minute
> differences in the appearance of conspecifics - as long as pre-feathers
> were visible it is possible that sexual selection had a role.  Sexual
> selection can be responsible for the spread of a mutant gene which does
> not aid survival in any way, and the significance of Michael Ryan's work
> on frogs is the demonstration that a female preference can be present
> BEFORE the male characteristic evolves.
> (Also, are you saying that it is impossible for ANY structure to evolve
> purely for display without having had a utilitarian origin?)
> 
> It is also possible (via genetic linkage) that this mutation spread via
> co-selection with something of genuine utility, ie classic natural selection.
>  Speculation I know, but plausible, not requiring miracles!
> 
> On Apr 28,  4:28am, Dinogeorge wrote:
> >
> > I don't maintain an aerodynamic origin for feathers. I currently favor a
> > metabolic origin for feathers. This >is< compelling, in that feathers 
> > thereby
> > fill a prior physiological need of the organism.
> 
> >From your previous posts, it is clear that you don't mean a physiological
> need to support sustained flight in your descendents - could you elaborate
> on the prior physiological need aspect, ie what was the need which other
> reptiles did not share?
> 
> Just to be clear, I have no strong views on which, if any, of the competing
> theories of feather origins is correct - food capture doesn't seem likely,
> and I agree with you that flight was probably not the initial function of
> feathers.
> 
> Tony