retroviruses; mammals

[Ken Kinman]

     Although many viruses are probably "escaped genes", I think the
statement by Margulis and Schwartz is perhaps a little simplistic.
     I would guess that viruses have been popping in and out of genomes
since the origin of life (pardon my using non-scientific jargon like
"popping in and out").  It would not surprise me at all if it turned out
that all DNA viruses (for example) had a common viral ancestry independent
of the genes they might borrow from their hosts.  Wouldn't these borrowed
host genes would be the first to go when a virus adapts to a new kind of
host (e.g., pull out the old "reptile" domain and plug in a new "mammal"
domain).
     Whether you want to call them alive or not really doesn't matter much
to me.   But until I am told otherwise by a virologist with convincing
arguments, I will hold onto my belief in a very ancient origin of viruses,
and that their histories may eventually be traced.  Any virologists
listening in?
                  -------Ken Kinman

> >Nor I.  But in Margulis and Schwartz's Five Kingdoms they state:
> >Viruses are probably related more closely to their hosts than to each
>other.  They may have originated as nucleic acids that escaped from cells
>and began replicating on their own -- always, of course by returning to use
>the complex chemicals and structures in their former home cells.  Thus the
>polio and flu viruses are probably more related to people, and the tobacco
>mosaic virus (TMV)
> >to tobacco, than polio and TMV are to each other."
> >
>Lets think about this folks.  If the above statement were true and viruses
>are "alive" then life one earth has evolved a gazillion times.  Do they
>truly believe that viruses keep originating de novo?  Is this the accepted
>view of viral evolution?  It doesn't matter what their DNA/RNA says if the
>truth of their history is a point origin in time.  Related means history
>not genetic similarity, no matter how hard that history is to see or is
>confounded by assimilation of new gene sequences.
>Julian Humphries
>University of New Orleans

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