Re: Origin of feathers

[Dinogeorge <Dinogeorge@aol.com>]

In a message dated 98-04-28 02:37:07 EDT, Patrick.Norton@state.me.us writes:

<< Watch out for circular logic, George. If you assert both your statements   
 to be true, then your theory about an aerodynamic-related origin of   
 feathers is not a compelling evolutionary scenario either, since other   
 animals evolved flight without "needing feathers to do so." >>

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. Feathers did not >originate<
to fill some aerodynamic purpose; they were exapted for an aerodynamic purpose
after they appeared. The ultimate cause of the appearance of feathers--or
primitive structures that were homologous to the feathers we are now familiar
with in birds--is random mutation together with the initial selection effect
that preserved that mutation in the population where it originated. That
initial selection effect, I assert, must have been physiological.