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Re: Evolution of sleep



Hi Don,
I found a paper on-line recently, which may be of some help: Siegel JM
(1997), Sleep in monotremes; implications for the evolution of REM sleep,
from Sleep and Sleep Disorders; From Molecule to Behaviour, p.113-128.
http://www.npi.ucla.edu/sleepresearch/113/113.pdf

It doesn't directly address your question, but it's of relevance.
Consequently, the following quote from page 114 is somewhat out of context.
Being that in mind, Siegel wrote: "The only mammal other than the echidna
that has been reported to lack REM sleep is the dolphin (Tursiops truncatus
and Phoecena phoncena) (Mukhametov, 1987; Mukhametov et al., 1977)."

I decided not to attempt any kind of article anchored on the paper, which is
my way of saying I found it very hard going.  Even bearing in mind that he's
not a paleontologist, the mention of "ancient egg laying reptiles called
therapsids" left me feeling queasy, as do the not particularly relevant
appearances of "cretaceous", "allosaurus", "stegosaurus", "tyrannosaurus"
and "triceratops" on page 115.  At least he gave the monotreme genera the
capital letters they merit!  I found those lapses somewhat off-putting, but
it doesn't mean the author is sloppy with his own speciality.

I think I read that the short-beaked echidna, (Tachyglossus), has
subsequently been found guilty of indulging in REM sleep at the correct sort
of temperature.  Siegel sensibly points out that the studies of dolphins
might be misleading, as the animals were in captivity, and their sleep
patterns could have been disrupted by the experience.

If all other studied mammals do indeed have REM sleep, then sleep per se
would presumably be universal among mammals.

<<Hard to see the advantage of being unconscious in a "bad neighborhood".>>

It keeps your off the streets, and saves on fuel bills.
Cheers,
Trevor

Mesozoic Eucynodonts
http://home.arcor.de/ktdykes/meseucaz.htm
The Mesozoic - more than just the dinosaur

----- Original Message -----
From: "don ohmes" <d_ohmes@yahoo.com>
To: <dinosaur@usc.edu>
Sent: Thursday, March 17, 2005 5:47 PM
Subject: Evolution of sleep


> Are there any widely accepted theories addressing the
> evolution of sleep in mammals? Any mammals that do
> w/out?
> Hard to see the advantage of being unconscious in a
> "bad neighborhood".