Newsgroups: comp.ai.alife
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From: mwd@cray.com (Mark Dalton)
Subject: Re: "What is Life?"
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References: <jhansen-120195102007@cetq10.coe.uga.edu>
Date: 14 Jan 95 15:44:08 CST

Jon Hansen (jhansen@moe.coe.uga.edu) wrote:
: Hello all,
: I am a biology teacher and some of my students have been wondering about
: the defining characteristics of life.  I thought it would be a good
: exercise for them to read real scientists definitions of life.  So if any
: of you are interested in helping some high school biology students wrestle
: with the most significant question in biology, please just write a simple,
: concise parapgraph that answers the question, "What is life?"  Thanks so
: much.  I really appreciate all the help you can give.
: C. Scott Williams
: cscotwil@moe.coe.uga.edu

I am not sure ANYONE can answer this  (^8.  This is the 'artificial life'
which is pretty vague also (in the sense of life).

But I will take a stab (of course it is not 'correct').

Life requires certain characteristics:
	1. Ability to grow.
	2. Ability to change/adapt.
	3. Ability to reproduce.
	
	I would added that they can grow or change on thier own.  And they
	can reproduce either by them self or though 'mating'
	 (I just want to eliminate virus as living.)

An analogy *may* help state why I think this and approach it from this
perspective. (In computer terms, sort of):

    This is WEAK, but it may convey the idea.
	Think of life as a Computer Hardware and software.

	 - A virus would be like just the software (DNA/RNA)/ability to
	   change and grow etc. Only if it had the hardware available to it.
	   And it IS very adaptable.
	 - A salt crystal can grow and 'reproduce' but it does not really
	   change or adapt.

So for Computers or software to become 'life', I think that both the
hardware and software need to be able to grow, adapt, reproduce.
	- rewire themselves, modify the next generation they build.
	- Be able to expand.

   AI has traditionally just done the software side (as far as I know).

I still think it would be quite amazing to build a small robot that can
build the next robot, and also be able to modify it self.  (Of course,
if something becomes 'alive' there are ethical questions that should have
been previously addressed).

Well, maybe this will get another discussion going?  (^8

Mark
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Mark Dalton       CH3-S-CH2 H                      H      O       H
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