Are viruses alive?

paul-michael agapow agapow at latcs1.lat.oz.au
Wed Jul 22 22:36:26 EST 1992


pkarp at ai.sri.com (Peter Karp) 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.  Therefore, a virus
>is not an autonomous biological self-replicating system because it
>requires the presence of other self-replicating entities to replicate.
>Whether it is alive or not depends on whether you equate life with an
>autonomous biological self-replicating system, or simply a biological
>self-replicating system.

Might i point out that this excludes all forms of sexually reproducing
life, since they are incapable of evolving without another form of life
(of the opposite sex) to reproduce with.

Nonetheless, Morowitz's definition is a brave attempt - i've just been
tangling with the definition problem and evntually concluded that the
problem was best handled if reduced to :

"X may not be alive, but for the purposes of discussion, we may regard it
as being such, or acting exactly as if it is ..."

This avoids a lot of the sticky problems involved in the philosophy of the
problem. Examining Morowitz's definition again, it strikes me that he
places a heavy (perhaps too heavy) emphasis on evolution. There seems to
be two problems here : firstly defining what an entity is (where does it
start and finish, how is it distinct from its environ and other entities),
and the separation of evolution from other behaviours. Strictly speaking
we could treat evolution as the adaptation of the "meta-organism", the
ancestral line of organisms. This itself gives rise to two interesting
questions - does an organism have to evolve to be alive or just adapt?
Does a virus adapt?

Hmmm,

p-m

--------------------------------------------------------------------------------
paul-michael agapow (agapow at latcs1.oz.au) Machine Intelligence Lab, LaTrobe Uni

        "Teenage sex, nuclear winter, Junior Miss fashion 
               & the mechanics of emotional capitalism ..."



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