Re: Life (comments on Mario's paper)
Alexei Sharov (sharov@VT.EDU)
Mon, 21 Sep 1998 08:44:52 -0400
>> 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