Are viruses alive?

[Geoffrey M Henebry]

jk13+ at andrew.cmu.edu (Joanne M. Karohl) writes:

>Peter writes:

>>Harold Morowitz' forthcoming book, "Metabolism Recapitulates
>>Biogenesis: The Beginnings of Cellular Life" has a succinct definition
>>of living systems.  To paraphrase from a draft of the book, an
>>autonomous biological self-replicating system is a molecular
>>self-replicating entity that is capable of evolving, and that operates
>>in the absence of other self-replicating entities.       ^^^^^^^^^^^^^
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>This definition of life does exclude many symbiotic organisms, such as
>the malaria parasite and others, which require host organisms to
>complete their life
>cycles . . .

>Joanne

the definition is in need of spatio-temporal bounds to make sense. every
living thing depends upon other living things for necessary supplies of 
nutrients and energy from which to self-replicate. i can think of no instances
in which organisms persist in environments untouched by the influence of other
organisms. 

Robert Rosen offers a provocative view of what sort of thing is an organism
in his recent book "Life Itself".  

from a passage toward the end of the book: 

"A material system is an organism if, and only if, it is closed to efficient
causation.  That is, if F is any component of such a system, the question
'Why F?' has an answer within the system, which corresponds to the category of
efficient cause of F. ... We claim that everything else about organisms,
everything studied in biology by biologists, and much else besides, arises
from and devolves upon this property. ... This is indeed biology from a new
and different perspective.  For one thing, it places the heart of biology 
entirely outside the scope of mechanism.  This is in itself illuminating; it
allows us finally to understand why the initial presumption of mechanism has
made the basic question 'What is life' inaccessible and unanswerable."

any comments? :)
                  geoff
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