Colin Rowat writes:
> I have a question regarding the evolution of any species with
>specialized members that would require many generations to serve a
>useful purpose. A specific example is that of wings: clearly, for the
>first n generations, the "ancestors" of wings would not be
>evolutionarily adaptive but would rather be a hinderance until they
>became flight-able. I wonder, then, what mechanisms can be used to
>explain members such as these.
If you can show that the ancestors of a specialized member would indeed
have been a hindrance, then you would have a valid question. However, the
ancestors of wings are not a good example. Flying squirrels do not have
wings, and it will probably be millions of years before they can fly like
bats (if they ever do). However, the membranes between their front and
rear legs are clearly useful for gliding safely out of trees to avoid
danger or to break a fall, and I see no reason to think that smaller
membranes were EVER a hindrance rather than a help.
In addition, animals that jump or run fast probably will run faster or jump
farther if they are aerodynamic. Animals that jump may also find it useful
to have "control surfaces" which allow them to control their attitude while
ballistic.
Creationists often cite the perfection of the eye as an example of
something that cannot be explained by evolution. But you can start
removing the advanced features of the eye one by one and still have
something that's better than nothing, even if you end up with a simple
trace of light-sensitive chemicals. Even single-celled plankton detect
light and rise and fall in the ocean depending on the time of day.
Ben Jones BioQUEST / Department of Biology
jonesbb at beloit.edu Beloit College, Beloit, Wisconsin
