In article <CMM.0.90.2.711650592.pkarp at Rockaway.AI.SRI.COM> 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.
Hmm. So humans must not be "autonomous biological self-replicating systems"
because we depend on oxygen, vitamin C and various amino acids. But I think
that most people would claim to be alive (or object violently if someone else
claimed that they were not!) so we must drop the "autonomous" in our general
definition. Anyway, the only creatures that are fully autonomous are
prototrophic bacteria that can use simple minerals to build everything they
need.
Ok, now that we've established that viruses are "alive" (because you can't draw
a line!) what about small pox? It will be destroyed completely in a few years;
it is only in certain labs now. But wait! A mad scientist resynthesizes the
genetic material from a GenBank entry 100 years from now, and everybody gets
infected. Was it alive while in GenBank?
Tom Schneider
National Cancer Institute
Laboratory of Mathematical Biology
Frederick, Maryland 21702-1201
toms at ncifcrf.gov
