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From: lincoln@randvax.UUCP
Newsgroups: sci.bio,sci.med,comp.ai,sci.misc
Subject: Re: Models of biological aging
Message-ID: <300@iris.randvax.UUCP>
Date: Tue, 16-Jun-87 00:51:54 EDT
Article-I.D.: iris.300
Posted: Tue Jun 16 00:51:54 1987
Date-Received: Thu, 18-Jun-87 04:07:51 EDT
References: <622@unicus.UUCP> <1343@sigi.Colorado.EDU> <1756@ttrdc.UUCP>
Reply-To: lincoln@iris.UUCP (Tom Lincoln)
Organization: Rand Corp., Santa Monica
Lines: 24
Xref: utgpu sci.bio:385 sci.med:2098 comp.ai:497 sci.misc:290
Summary: There is something counter-intuitive about 2^50

In article <1756@ttrdc.UUCP> levy@ttrdc.UUCP (Daniel R. Levy) writes:
>In article <1343@sigi.Colorado.EDU>, eddy@boulder.Colorado.EDU (Sean Eddy) writes:
>< Hayflick limit: In actual practice, it is not thought that any
>< human cell approaches 50 divisions during the human lifetime.
>
>Is this true even for skin cells? ....that intestinal cells continually
>regenerate and get sloughed off during the normal digestive process.
>That's a lot of cell division, or am I mistaken?)

2^50 is a very large number, if every cell had two progeny (which of course
they don't) - but the rate of proliferation is impressive. In fifty
divisions two cells would produce something like 10,000 lbs of tissue. Thus
a little proliferation goes a long way.

There is the story about the man who was granted one wish by the king...
that the king would place one grain of wheat on the first square of a
chessboard, and double it every square thereafter... by 55 he was well on
the way toward taking over the entire world.

 p q
 \|/
 /|\   TOM LINCOLN  lincoln@rand-unix.ARPA
 \|/  "Life is short, art is long, opportunity fugitive,
 /|\   experimenting dangerous, reasoning difficult."