One origin? (viral evolution)
kinman at HOTMAIL.COM
Fri Jul 20 14:27:24 CDT 2001
My view is that viruses (sensu lato) preceded cells, and that the
earliest living biochemical pathways developed in an acellular "organic
soup" (as it is called). Membranes would have just gotten in the way in the
beginning. Exactly how membranes originated and then evolved is still hotly
debated, but a membrane without nucleic acids is not living any more than a
quartz crystal is. Membranes are just highly evolved "walls" and
Therefore I regard viruses as living, and leftover stragglers from the
precellular "organic soup". When cells evolved and the "soup" got too thin,
viruses had to begin infecting the cellular (partitioned) packets of soup
(bacteria, sensu lato) in order to reproduce, and viruses have been popping
in and out cells (and even the genomes of those cells) ever since.
In a sense chromosomes are just big highly evolved viruses, and cells
are the protective cocoon they build around themselves so that they can
continue their highly-evolved, complex lives (and to reproduce). What we
refer to as viruses are like small homeless primitive relatives that now
have to come to their cellular relatives for handouts in order to survive
and reproduce (often killing the host cell in the process).
All these homeless wandering viruses I classify in Class Viralea. The
chromosomes that had cellular homes were originally all bacteria, but one
bacterium eventually evolved into a nucleated form. These eukaryotes are
just chromosomes that live within a secondary home (nucleus) within the
original cell. Perhaps this nucleus was effective at keeping out primitive
viruses, but more advanced viruses would then have evolved that could get
through this secondary defense.
Anyway, evolution is a complex reticulate puzzle, and as Ernst Mayr has
shown, the most fundamental and useful division of life is prokaryote vs.
eukaryote. Viruses and bacteria were around long before eukaryotes, so I
classify them all in Kingdom Monera and refer to them collectively as
prokaryotes (which is an appropriate term in my view).
So, viruses have no real home at all, bacterial chromosomes have a
simple home, but only eukaryotes have the nucleated "home within a home".
The fact that some complex viruses can infect eukaryotic nuclei (and even
steal bits of their genetic material) does not make them eukaryotes. They
are basically still primitive acellular prokaryotes camouflaged by some bits
of eukaryotic clothing (of sorts) taken and modified from a long line of
infected hosts. When we have whole genomes sequenced, we will someday be
able to trace some of these very complicated and reticulated viral
>From: Thomas Lammers <lammers at VAXA.CIS.UWOSH.EDU>
>Reply-To: Thomas Lammers <lammers at VAXA.CIS.UWOSH.EDU>
>To: TAXACOM at USOBI.ORG
>Subject: Re: One origin? (viral evolution)
>Date: Fri, 20 Jul 2001 12:03:23 -0500
>At 12:40 PM 7/20/01 -0400, you wrote:
>>As I am a theorist here, can it be that in this thread we have come to a
>>sacred cow. That is, to acknowledge that viruses are living yet so unlike
>>other life is to acknowledge more than one tree, root, seed for life here?
>>Which would open Pandora's box to other more drastic idiomatic quakes.
>It would seem that nucleic acids and their whole replication business stems
>from a single origin, so in that sense, all life (sensu stricto) has one
>origin. And it seems that the cell has but one origin. I guess the
>question rests on the relationship between the two, i.e., do viruses
>predate the cell or vive versa?
>Thomas G. Lammers, Ph.D.
>Assistant Professor and Curator of the Herbarium (OSH)
>Department of Biology and Microbiology
>University of Wisconsin Oshkosh
>Oshkosh, Wisconsin 54901-8640 USA
>e-mail: lammers at uwosh.edu
>Plant systematics; classification, nomenclature, evolution, and
>biogeography of the Campanulaceae s. lat.
>"Today's mighty oak is yesterday's nut that stood his ground."
> -- Anonymous
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