A possible definition of life.

Ed Rybicki ed at MOLBIOL.UCT.AC.ZA
Thu Apr 24 02:42:40 EST 1997


> From:          "Kirk Elder" <gt6873d at prism.gatech.edu>
> Subject:       Re: A possible definition of life.

...
> life needs to be free from all constraints that REQUIRE an external entity,
> that not only assigns its growth (mentally, physically, abstractly) but
> interprets its actions.
> This throws a serious wrench into the subject.  I think this takes the
> photocopier out of the picture, and the thermostat.  

So does any definition requiring that a living thing code for itself 
AND replicate itself.

> Life does what it chooses to, when it chooses to, and how it chooses to do
> it. 
> Can anybody think of a living creature, (agreed upon beforehand) that
> doesn't obey this rule. 

The concept of choice, when talking about even the organisms we know, 
is a a very difficult one: does a bacterium "choose" to follow a 
concentration gradient of a nutrient, or is its behaviour programmed 
to such an extent that it is involuntary?  Does a virus "choose" 
which cells it attaches to, or whether it will infect it?  I suspect 
the smaller you go, the more programmed things are, in terms of 
intermolecular interactions; thus the concept of "choice" in 
determining what an organism does, falls away.

Good thread...B-)

                     Ed Rybicki, PhD  
      Dept Microbiology     |   ed at molbiol.uct.ac.za   
   University of Cape Town  | rybicki at uctvms.uct.ac.za
   Private Bag, Rondebosch  |  phone: x27-21-650-3265
      7700, South Africa    |   fax: x27-21-689 7573
    WWW URL: http://www.uct.ac.za/microbiology/ed.html      
                                        
"Every year is getting shorter, never seem to find the time..."



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