Re: what is life

From: Chris Gordon-Smith (address_at_homepage.net)
Date: 08/03/04 

Date: Tue, 3 Aug 2004 04:25:10 +0000 (UTC)

Tim Tyler wrote:

> Chris Gordon-Smith <address@homepage.net> wrote or quoted:
>
>> haiguang wrote:
>
>> > In his book "the origins of life", Freeman Dyson showed something more
>> > important than metabolism: replication. In his opinion, life must be
>> > able to reproduce itself, and that is really the meaning of life.
>> > Nowadays, more and more scientists agree with this idea.
>>
>> The key point about Freeman Dyson's book is that he is making the case
>> for life having a metabolic origin, rather than having an origin as a
>> template replicating molecule.
>>
>> I don't think anyone doubts that life must be able to reproduce itself,
>> although it is of course possible for an individual organism to be alive
>> without having the ability to reproduce.
>
> Life needs to be able to perpetuate itself.
>
> Reproduction dosen't seem to be logically necessary - it would be
> possible for a living system to consist of a single large entity
> that grew into new environments rather than reproducting itself -
> and most would still judge such an organism to be alive.
>
> There are large plants that operate like this - vegetative growth -
> rather than reproduction.
>
> Consider, for example:
>
> ``Lomatia tasmanica: the oldest clonal plant on the planet''
>
> http://www.research.utas.edu.au/reports/1998/clone.htm
>
> ...an article about the world's oldest known living thing.

The ability to reproduce is certainly not necessary for an organism to be
alive. The plant you mention is alive, as are animals above reproducing
age.

However, reproduction does seem to be necessary for the origin and survival
of the living world.

i) Lomatia tasmanica is the product of a long process of evolutionary
selection, and reproduction seems to be necessary for evolution (selection
has to have something to work on)

ii) A species that does not reproduce and which cannot evolve is unable to
adapt to changing conditions, and so is unlikely to survive in the long
term (although I suppose it might stand a better chance if other species
are also not evolving)

iii) Even though Lomatia tasmanica may perpetuate itself by growth, this
growth does of course depend on the individual cells of this multicellular
organism being able to reproduce

If you are not already aware of it, you might be interested in the
distinction that is made between 'Real' and 'Potential' life criteria that
is made by Tibor Ganti in the book "The Principles of Life". A summary of
the criteria can be found at:-

http://home.wxs.nl/~gkorthof/korthof66.htm 

-- 
Chris Gordon-Smith
London
Homepage: http://graffiti.virgin.net/c.gordon-smith/
Email Address: Please see my Home Page

Relevant Pages

  • Re: Questions about the Upper Paleolithic
    ... Since most critters can reproduce pretty fast, life ... Adaptedness ... adaptation is to be clever enough to find and exploit new ...
    (sci.anthropology.paleo)
  • Re: What is biological life?
    ... >>>troubled that there is no crisp definition for biological life. ... >>I noticed a couple of things that seem to be common to all living ... They reproduce ... > maybe of individual characteristics common in a group, ...
    (talk.origins)
  • Re: Images: A Womans Right To Choose
    ... Arbitrary crapola. ... gay couples etc etc etc cannot reproduce in kind ... It is now accepted, for instance, that the unborn child is able to sense the ... We should never forget that the birth process is not the 'start' of life - ...
    (rec.photo.digital)
  • Re: How to increase lifespan indefinetely...
    ... >>be a gradual evolution of longer lifespans, ... lifespan, these Methusalah flies bred much later in life than normal flies. ... problem with the number of times their cells can reproduce. ...
    (sci.bio.evolution)
  • Re: the meaning of life
    ... see Life and Living ... Adaptation - Adaptation is the accommodation of a living organism ... considered replicators rather than forms of life: they cannot reproduce ...
    (sci.physics)