To expand the question:
Assuming sleep correlates with sharply reduced
alertness/awareness, what is the across-the-board
selective advantage of unconsciousness that prevents
at least some vertebrate animals from evolving always
on status relative to mental awareness? Or if there
are some, why are they rare?
Is it a systemic weakness that selection cannot
overcome? I can rest w/out sleeping, but sleep I will,
even in the face of certain death.
Don
--- K and T Dykes <ktdykes@arcor.de> wrote:
<<REM sleep is much more common. Crocodiles and very
young birds show it,
and I forgot what else.>>
I wouldn't be surprised about that, David. However,
the question concerned
only mammals.
<<Sleep per se is common to all... vertebrates?>>
This must be another interesting question, because I
don't know the answer
either. Happily, there's a good chance somebody
else will be able to
enlighten us both. That's the great thing about
ignorance. It leaves
plenty of
room for learning new stuff.
Cheers
Trevor
Mesozoic Eucynodonts
http://home.arcor.de/ktdykes/meseucaz.htm
The Mesozoic - more than just the dinosaur.