A possible definition of life.

Rob Miller rmiller at house.med.und.ac.za
Mon Apr 21 04:23:33 EST 1997

James Foster wrote:
> In article <m0wHUt6-0004OBC at uctmail2.uct.ac.za> ed at MOLBIOL.UCT.AC.ZA ("Ed Rybicki") writes:
>     "Life (anywhere) is the phenomenon associated with th replication of
>    self-coding informational systems".
> This is too imprecise.  To which phenomena do you refer?  Replication?
> Self-coding?  Decoding?  Translation?  Does your definition make my
> copy program alive?  How about my photocopier?

Seems pretty precise to me -- Ed's statement implies to me the
(singular) which is specifically the existence and function of
informational systems.'  Your photocopier is clearly not self-coding,
your copy program is not sufficiently self-coding to replicate on its
(without more assistance than the `natural phenomena' occurring on your 
hard drive - like a computer virus could get by with).

> I remember a philosophy paper in college arguing that thermostats were
> alive: they are self regulating, have internal representations, must
> be in a host, etc.

But they are not self-coding.

> Personally, I think defining life is a fool's errand.  We're not

Or perhaps a hobby for net-nerds like us :-)

> really interested in "what is life".  Ed is interested in how viruses
> do what they do.  Alife people are interested in algorithms which
> display interesting behaviors.  You don't have to define the term to
> justify what you do, or even as a prerequisite to doing it.

I think Ed's interested in the question on a lot of levels, as am I. 
gives me insights into models of protein folding, and I believe a lot of 
Alife `experts' would be at least annoyed by your justification of their 
field as an opportunity to `display interesting behaviors.'  Just as 
many AI folk believe they are gaining insight into human intelligence 
with their work, defining (and modelling) life helps us understand 
what constitutes life, how it works, and what we really mean by the

Not trying to flame, just carrying on an interesting thread and ....

> University of Idaho 

  ^ I (mostly) grew up within 2 miles of your desk !


Robert T. Miller, Ph.D.                               
rmiller at sanbi.ac.za
Manager, Durban Satellite, South African National Bioinformatics
Department of Molecular Virology,  University of Natal,  Durban, S.
h: www.sanbi.ac.za   p: +27 (0)31 2604580  f: +27 (0)31 3603744 or

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