Moosh:] writes
On Sat, 19 Jul 2003 10:47:54 +0100, Oz
wrote:

Moosh:] writes

Modern hygiene clears up viri as much as bacteria.

Yes, but given little to do the viral one dominates.

I wonder why.

probably because the systems evolved in a situation where bacteria
dominate.

So why would the viral one dominate? Sorry for being dense, I was
force-fed pasteurised milk as a child

Because for a billion years of evolution bacterial challenge was forever
dominant. So when you have a see-saw, best to bias it away from the
direction it is pushed, I would guess.

Because it's dominant in animals and third world countries.
Bacteria are a continual challenge.
Viruses are only successful when they find an immunologically naive
organism, which is quite hard without movement between distant
populations.

Sorry, how do you know bacterial challenge was dominant over these
years? There is lots of vestigial organelle evidence for viral
invasions over the aeons.

I never said viruses didn't exist. They did and do. I said for most wild
populations bacteria offer a continual challenge, not viruses which tend
to be rare and sporadic.

Certainly in evolutionary terms it's very very recent that man lived in
large (say 2000+) closely packed groups with good communication between
groups.

Within the groups, surely. Ten to 30 k anni?

Eh?

Which bit? I'm sure the groups competed with little communication
between them.
Ten to 30 thousand years?

Start of agriculture, really, so yes.
Pretty well irrelevant time for a major change in a deep seated and
complex genetic makeup.

I would thus imagine that new viral attacks were very rare (and
probably pretty devastating).

Well they still are in modern times. Flu and small pox to name just
two.

They are probably predominant in modern times. Bacterial attack being
squashed with antibiotics. Remember a lot of flu (eg 'common cold' and
gastroenteritis is viral today.

And I'd assumed it was ever thus. I would guess that antibiotics have
had close to zero effect on bacteria. Do you know of any that have
gone extinct?

The main human pathogens (ie they make people very ill) are very rare.
Remember that before antibiotics hospitals were predominantly filled
with bacterially infected people. The 'fever wards'.

Typically the local endemic viruses would
have all been encountered in childhood. Bacterial challenge, though,
would continue throughout life.

Well I still get regular (but seldom) colds and flu, how about you?

Yes, but I probably get mild bacterial infections of the gut every
couple of weeks, and for sure when walking and working in cow slurry I
must be getting a substantial bacterial challenge. Remember that a
challenge that is 'dealt with' is still a challenge and the immune
response is triggered even if no serious (or even observable) illness
results.

Of course. Same with viri

Indeed, however most viruses are highly species-specific, most bacteria
are not. ECO157 can happily move from cow to person whilst BVD cannot.
So typically bacteria get a bit of a permanent toehold moving between
species whilst viruses typically exist at very low level in an
immunologically resistant population and only get to attack each
individual once.


--
Oz
This post is worth absolutely nothing and is probably fallacious.
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