Alexei Sharov wrote:
> >> Mario, you have not answered my question. I don't mind if you can call
> viruses
> >> informational parasites. The questions are: are they replicators and
> >> are they alive?
> >
> >They are not replicators: they depend on the gene replication machinery of
> other
> >organisms for the replication of their genes.Other parasites do not. Other
> > parasites
> >depend only for metabolism on other organisms, having their own replication
> >machinery.
> >
> >Are they alive? They do not have metabolism, so what?
> >Am I alive? I have metabolic funtions, so what?
> >I am part of a 4 billion year old organism which is a trillion, trillion, ...
> >billion cells large. Isolate me (or any other 'living organism' or a virus)
> from
> > the
> >rest of this organism and processes in my body (or the replication of the
> virus)
> >will soon stop. You can not answer the question of what life is by studying a
> > single
> >living organism. Life as we now it is the metabolic network formed by all the
> >descendants of that first cell. I think that when you can explain the origin
of
> > the
> >first cell, that the rest of the explanations follows.
> >Viruses are part of the organism Life, but asking whether they are alive is
the
> >wrong kind of question I believe, just the same as asking whether I am
alive.]
>
> I agree that life is a network, but I found it useful to distinguish
> several levels of autonomy in this network. If a system has a freedom
> to change its links with other systems it becomes more-or-less autonomous.
> Predator depends on its prey, but it may change its diet and start
> feeding on other prey if the initial kinds of prey become scarce.
> Although viruses are highly specialized, they also can change thier
> host in the evolutionary time scale.
>
> -Alexei
> -------------------------------------------------
> Alexei Sharov Research Scientist
> Dept. of Entomology, Virginia Tech, Blacksburg, VA 24061
> Tel. (540) 231-7316; FAX (540) 231-9131; e-mail sharov@vt.edu
> Home page: http://www.gypsymoth.ento.vt.edu/~sharov/alexei.html