Reclassifying Viruses as Living?

Richard Pyle deepreef at BISHOPMUSEUM.ORG
Tue Mar 14 22:49:48 CST 2006

The way I like to distinguish "life" from "non-living chemistry" is that the
former is defined largely by the "flow" of information over time.  "Flow"
not in the physical sense, but in the sense that the "information"
transcends its physical basis in matter, and perpetuates imperfectly.

If you take some heterogenous form of atomic matter (elements and
molecules), and combine it under a particular set of physical circumstances,
it will yield a predictable (i.e., the same) set of products over and over
again.  This is what I would classify as non-living chemistry. But if the
products are not completely predictable (by laws of physics) over time and
multiple replicates, then something is happening. That "something" is
information, and the flow of information over timespans that exceed the
physical/material manifestations of the information storage system is the
essence of "life", in my view. What makes "information" in this sense
different from the simple physics of cause and effect, is that the reactions
involved with non-living chemistry do not change if the physical environment
does not change.  A chemical reaction will follow the same pattern in the
same conditions, even if it is separated by billions of years and occurs in
different parts of the universe.  But information is mutable, and as such is
itself the product of a legacy of information flow.  It is this flow of
information that unites all living things on planet Earth (as far as we now

Now, clearly there are examples of infromation "flow" that are non-living,
and there are different ways of defining what constitutes "information".  So
I don't pretend that this is the be-all and end-all distinction between life
and non-living chemistry. But it (information flow) does strike me as a
fundamental characteristic (perhaps THE fundamental characteristic) of
"life". Also, although most of what we think of as "life" is organized in
cohesive (more or less) units that represent collections (sacks) of
non-living chemistry, and much of this (organic) chemistry is unique to
living processes (e.g., metabolic pathways), to me those chemical reactions
per se are not really what "defines" life.

So, I tend to side with others who regard viruses as within the realm of
"life".  I find this a particularly easy conclusion to arrive at given that,
as has already been pointed out, the information content of viruses is
stored in the same basic material form as the information stored in
everything else we lump under the umbrella of "life".

To me, a trickier (and perhaps more interesting) question is: what are
prions?  Life, or non-living chemistry? I personally favor the latter
interpretation in this case.


P.S. Sorry about's late, and I'm tired, and I'm avoiding the work
that I really should be doing right now...

Richard L. Pyle, PhD
Database Coordinator for Natural Sciences
  and Associate Zoologist in Ichthyology
Department of Natural Sciences, Bishop Museum
1525 Bernice St., Honolulu, HI 96817
Ph: (808)848-4115, Fax: (808)847-8252
email: deepreef at

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