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Article 2657 of comp.ai.philosophy:
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>From: weemba@libra.wistar.upenn.edu (Matthew P Wiener)
Newsgroups: comp.ai.philosophy
Subject: Re: Waking up is hard to do, but somebody's got to do it
Message-ID: <61968@netnews.upenn.edu>
Date: 12 Jan 92 21:30:22 GMT
References: <60551@netnews.upenn.edu> <334@tdatirv.UUCP> <60759@netnews.upenn.edu> <350@tdatirv.UUCP> <61668@netnews.upenn.edu> <363@tdatirv.UUCP>
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Reply-To: weemba@libra.wistar.upenn.edu (Matthew P Wiener)
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In-reply-to: sarima@tdatirv.UUCP (Stanley Friesen)

In article <363@tdatirv.UUCP>, sarima@tdatirv (Stanley Friesen) writes:
>In article <61668@netnews.upenn.edu> weemba@libra.wistar.upenn.edu (Matthew P Wiener) writes:
>|Remember: evolution of sleep did occur, even though some animals lose.

>That is my point, sort of.  It evolved, so the added benefit of sleeping
>*must* exceed the danger.

My point is that the dangers of sleep to species are not as great as the
danger to individuals.  I can even conceive of it evolving solely as an
energy conservation measure, and only later becoming more sophisticated.

>			    I think my model explains the benefit quite well.

But your model--preventative maintanance--has been explored and found
wanting for decades.

>Especially since sleep does *not* seem to be correlated with anything
>like 'intelligence'.

Actually, there is a correlation.  High EQ (encephelization quotient) species
seem to need more REM sleep than low EQ species.  Whether this correlation is
due to an underlying relationship or not is unknown.  If sleep is needed for
thermoregulation, than larger bodies will lead independently to both higher
intelligence and simpler thermoregulation.

(Actually actually, whether this correlation exists is a harder question.
Cross-species comparison of sleep is hard, and subject to all sorts of
selection effects.)

>		       Even reptiles enter torpor of some sort at
>various times.  It is not entirely clear that this is really any
>different than mammalian sleep.

Who knows?  Reptiles don't have REM sleep.  Very few mammal species (dolphins,
spiny anteaters, ????) don't.

>|>So what behavioral benefits come automatically with any consciousness at all?

>|Desire to survive is better than just instinct to survive.

>What does this mean?  What is a desire except a particular class of instinct?
>Or do you restrict the word 'instinct' to refer to insect style pre-wired
>behavior?  If so, there is precious little instinct amoung amniotes.
>[In short, I suspect the 'survival instinct' of even reptiles takes the form
>of *feelings*, like fear, hunger and so forth].

I refer to an active self-awareness to get food--tastes good!--rather than 
stop the stomach from growling--less filling!

>|>							     That is why
>|>most small animals sleep in burrows or holes in trees, and even bears seek
>|>out obscure, hard to find caves. [and why we generally limit our sleeping
>|>to our artificial caves - where we feel safe].

>|And warmth has nothing to do with it?

>Not in the tropics.  Humans live in buildings even in the warmest climates.

You'll also note that predators like lions generally sleep more than their
typical prey like zebras.  They eat their fill and laze around for days at
a time.

>| Assuming the dinosaurs were cold-
>|blooded, I'd expect that there was a massive slowdown of animal activity
>|at night 1e8 years BP.  Enough so that the mammals could get away with
>|evolving sleep.

>There is a problem here. Almost all Cretaceous mammals were *nocturnal*,
>sleeping, if at all, during the *day*, when the dinosaurs *were* active.

This is known?  Considering how varied dolphin sleep is from other mammals,
or even human from shrew, I find it quite difficult to buy the above based
on extrapolation from today's patterns.  Is there some other determination?

Are you implying that mammals did not need preventative maintence 1e8 years BP?

>Also, given that crocodiles doze, and birds apparently sleep, it is quite
>likely that dinosaurs themselves slept from time to time.

Right.  And they probably had some intelligence to boot.

>|>As stated above, your model of predation fails to allow adequately for
>|>opportunistic kills.  A very common occurance in nature.

>|No, opportunistic kills will still occur in my view.

>Exactly, and opportunistic kills are what makes sleep dangerous, so dangerous
>that it must have a simple, direct survival advantage.

I disagree at this point.  Predators that eat all their prey become instinct.
Lotke-Volterra dynamics permit a wide variety of individually dangerous
activity to go on.

>|>Perhaps, but it is necessary to demonstrate the need for the linkage.
>|>A linkage is an added component that needs independent verification.

>|There is independent verification: no physiological basis for sleep is
>|known, despite decades of research, and massive amounts of mind-based
>|correlations with sleep and near-sleep and waking are known.

>Unfortunately, these are also very weak, since sleep occurs in animals with
>relatively simple brains, and hence minds.

In humans, we can test cognition and hallucinations under voluntary sleep
deprivation.  In other species, sleep deprivation is incredibly stressful,
and this weakens and even kills numerous possible conclusions.

>					     It is almost as if any level of
>processing above that of reflex requires some form of sleep.

Yes!  Take out the "almost as if" and you've got what I've been arguing
for all along.

>|So what's your model of the evolution of sleep?  I've only seen one book
>|on the subject, and it doesn't get into the whys.

>I have already stated, it is for the purpose of Preventative Maintenance.
>It allows the body and brain to clear out the accumulation of crud associated
>with the day's activities.

>|For sure.  Total sleep deprivation of mice leads to death within three
>|weeks. 

>But what did they die *of*?  What was the *proximal* cause?  If it was
>any sort of physical collapse (like heart failure), this is perfectly
>consistant with the PM hypothesis.

The mice went on eating gorges, lost weight, developed skin lesions on
their paws and tails, and eventually their thermoregulation collapsed.
No proximal cause was identified.  No other problems were found, from
internal organs to the immune system.

Note that PM might be relevant to the paw and tail ulcers, but that
would be strange--why were there no other ulcers?  None under the fur,
and none internally.  Just the exposed naked skin.

It would be interesting to do this experiment with their exposed skin
protected.

>				     In fact this level of toxicity in
>unrested tissues would *easily* override the much smaller risk of death
>while sleeping.

What toxicity?

>What reason is there to think the death in this experiment was due to
>*mental* causes?

None.  The belief in that link is from the known cognitive distortions in
sleep-deprived humans.  A mere PM need would have to do a lot of explaining.

The mice's death is consistent with a cognitive need for sleep: they no
longer know to curl up their tails and tuck in their paws for heat
conservation, so they no longer know how to keep warm, and so they die.
-- 
-Matthew P Wiener (weemba@libra.wistar.upenn.edu)


