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what is alive?

Johnjoe McFadden j.mcfadden at surrey.ac.uk
Tue Sep 17 09:56:34 EST 1996


>Johnjoe McFadden wrote:
>> 
>> An apposite description of a virus that I once heard is:

>>  "A virus is a piece of bad news wrapped up in protein."
>>         (I cannot remember the source)

Mario.Vaneechoutte now writes:
>>

>A nice one.
>However, 'bad' and 'good' always depend on the point of view you take.
>For individual organisms, viruses surely are bad news. But, evolution
>and evolution towards more complex organisms owes a lot to viruses.
>Humans usually consider 'evolution towards more complex organisms' as
>good (otherwise we wouldn't have been here).

............................................
Many people do not see increasing complexity as 'good'. See eg. SJ Gould's
many excellent books including his latest (which I haven't yet read) which
argues strongly against the 'complexity=good' viewpoint. Anyway, viruses are
surely genetically-selfish elements that are in there for their own 'good',
not that of the host. Any role they may have had in evolution (and I am not
aware of any strong case where this has been demonstrated) is purel;y
accidental.

..............................

>> Both viruses and prions are information that can replicate themselves >if
injected into the right environment. 
>
>OK, but this definition applies to all life: e.g. as a human, just try
>to replicate yourself outside the human society.

Maybe that is because of an anthropocentric view. It is difficult to get
>rid of and to look at things from the point of view of information.
>For an exercise, see: http://www.club.innet.be/~claeys/boi/boi.html.
>Behavior of Information by Luc Claeys.

....................................
Sure, replication is neccessary for the procreation of life but is it what
defines life? No mule has ever replicated but I don't doubt that a mule is
alive. No definition of life is perfect but merely replicating information
is too broad - it could also bring in cultural stuff such as those
irritating chain mail letters and e-mail's that also replicate themselves
within the right environment (ie. a gullible reader). Life is a lot more
wonderful that a computer virus or a chain mail letter - not just more
complex - it differs at more fundemental levels.


Johnjoe

Johnjoe McFadden, PhD
Molecular Microbiology Group
School of Biological Sceinces
University of Surrey,
Guildford, Surrey GU2 5XH, UK.

tel: 44-(0)1483 300800 extn.2671
fax: 44-(0)1483 300374

e-mail: j.mcfadden at surrey.ac.uk




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