Since this keeps coming up, a little clarification might
be worthwhile (for me, anyway). 'Sex' in itself is not a
non-adaptive process; there has to be some means of
reproduction (ideally with a mechanism for trying new
gene combinations) for evolution to proceed. I think you
are referring to 'sexual selection', in which (typically)
females choose mates based on apparently non-adaptive
characters.
Even that concept seems questionable, though. Every organism
lives in its own world, its own niche. If I'm a male peacock,
I have to adapt to a world in which females look for that
big feather display. Fitness is determined by the existing
environment, not by abstract criteria. It can always be said
of a species that its strategies are not optimal as seen from
our position. Group selection, even ecosystem selection, can
come into play, fostering apparently non-adaptive strategies
among individual species.
Perhaps someone could itemize the non-adaptive processes
Dawkins (or anyone else) envisages? I guess I'm just wondering
how fuzzy the concept is.
-- Cliff Lundberg ~ San Francisco ~ cliff@noevalley.com