Xref: utzoo sci.bio:3263 sci.misc:4304
Path: utzoo!utgpu!watserv1!watmath!att!cbnewsl!arrizzo
From: arrizzo@cbnewsl.att.com (anthony.r.rizzo)
Newsgroups: sci.bio,sci.misc
Subject: Re: 25 hr day
Message-ID: <1990Jul12.212246.19272@cbnewsl.att.com>
Date: 12 Jul 90 21:22:46 GMT
References: <33843@ut-emx.UUCP>
Organization: AT&T Bell Laboratories
Lines: 47

In article <33843@ut-emx.UUCP> tmca@emx.UUCP (The Anarch) writes:
#OK, I gotta question:
#
#	I'm told, through various reputable sources, which I can't remember
#just this minute, that the majority of the human race lives on a 25 hr 
#schedule, and some on as long as a 27 hr schedule. By schedule, I mean
#circadian (sp?) rythms and such like. Now this is all very well, and would
#explain admirably why I can't get up of a morning, but, being a scientist
#'n'all, I can't help but think that there ought to be some good reason
#for this. After all, the Earth has been running on a 24 hr day for quite
#some time now, and I'd've thought that we'd have caught up by now. Anyone
#got any ideas?
#
#	On a related note, being an astronomer, I'm often faced with the
#transition from a day schedule to a night schedule and back again. Some
#years of practise have led me to the conclusion that I can only grin
#and bear it. Anyone got any better, more scientific ideas of how to
#deal with jet-lag?
#
#	Tim


This is a very interesting question.  I've heard the same statements
from equally reputable but unmemorable sources.  
I agree with you.  There must be some good reason for the mismatch,
and it must be evolutionary in nature.  Here's my idea:
the 25 hr to 27 hr cycle is observed only in the laboratory.
Individuals eventually reverse their sleep/waking periods
completely if their bodies are not permitted the luxury of
some form of clock or time reference, such as the sun.
However, outside of the laboratory such a time reference
is inevitable.  We're usually awakened by sunlight and
animal noises, in the absence of a timepiece.  Therefore,
outside of the laboratory, such as in the wild millions
of years ago as well as now, the body's cycle is reset
each morning.  I suggest that the longer cycle ensured
a necessary degree of alertness at dusk, when most
predators go hunting.  Individuals whose bodies were
on a 24 hr cycle probably became prey and didn't get
the chance to have offspring.  Individuals whose bodies
were on a 25 hr (or longer) cycle probably were able
to avoid becoming prey and got a chance to live long
enough to have offspring.  What do you think?


-- 
----------------------------------- tony -----------------------------------