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From: altenbur@plains.NoDak.edu (Karl Altenburg)
Subject: Defs for a Living System
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Date: Sun, 12 Feb 1995 18:52:13 GMT
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It seems a the definitions of life being passed around here have
a tendency to dwell on one aspect or another (i.e. evolution vs.
organization).  I though I would try a put together a broader list.

The following list of descriptions define a living system.  The examples
provided draw on biology but I've attempted to be general enough to 
permit other living systems.

What criticisms do you have of this list?  Are there recognizable 
life forms that do not have all/some/any of these characters?

I did not place them in any order of priority.

Here's the list:

Living systems are composed of a collection of heterogeneous, 
inter-related functional subsystems.  These subsystems function to
store, transform, and transmit energy or information; they may also
separate the living system from its environment.

Living systems are capable of self preservation.  Self preservation can
take many forms including repair of damaged subsystems, re-growth, and
reproduction.

Living systems are responsive to changes in the environment in which
they exist.  Responses include movement towards or away from a stimulus,
changes in growth, or changes in reproduction.

Living systems transfer energy or information from one state to another.
Transformations would include storing potential energy and generating
kinetic energy from potential energy sources, or decreasing and 
increasing entropy.

Livings systems can be damaged and terminated.


Here is another list for the initialization of living systems:

Accumulation of functional subsystems

Localized ordering of functional subsystems

Aggregation and isolation of functional subsystems

Replication of the entire aggregate of subsystems

-- 
Karl R Altenburg				altenbur@plains.NoDak.edu
North Dakota State University, Fargo, ND  58105

All things are artificial, for nature is the art of God.  SIR THOMAS BROWNE
