Re: NS and AaD curves

g wrote:
> "Anon." <bob.ohara@xxxxxxxxxxxxxxxxx> wrote in message
> news:dgpit8$2mic$1@xxxxxxxxxxxxxxxxxxxxxx
>
>>IRR wrote:
>>
>>>"g" <gillawton@xxxxxxxxxxxxx> wrote in message
>>>news:dgdjnj$1ed6$1@xxxxxxxxxxxxxxxxxxxxxx
>>
>>There may also be another factor here. The Spanish 'flu spread at the
>>end of WWI, so many of the deaths in the middle of the range were
>>probably of soldiers in the trenches: they would not have been in the
>>best of health anyway, so would have been more susceptible. And the
>>conditions would have made spread easier (as the men were all living
>>together).
>>
>>I don't read the epidemiological literature, so I don't have any
>>detailed analysis, but this seems to be plausible. It's certainly an
>>off-quoted statistic that more soldiers died of the 'flu than were
>>killed in actual combat.
>>
>>Bob
>
>
> Bob,
>
> VERY ACUTE thinking.

Thank you. Perhaps it's because I use to work as an epidemiologist.

This did come over as being extremely patronising. It's clear that you
don't know much about infectious disease epidemiology (have you heard of
SIR epidemics?), so this sort of comment is not appreciated.

But keep in mind that in my message I was having a
> little satirizing fun with the
> notion of "natural selection" and "survival of the fittest."
>
> The "W-shaped" epidemiological statistical AaD (age at death) distribution
> for flu-year 1918-1919 applied fairly generally.
>
> Yes, you are right on about deaths in the trenches. Deaths by age in the U.
> S., generally, however, plotted the same way, which is a curious thing, and
> here is why: While I do not have on hand any details about the
> primary, secondary and tertiary stages of the pandemic influenza strain,
> there is with many such acute infections a period of incubation with mild
> symptoms, followed by a period of sepsis (where the virus hits a peak level
> of cellular invasion), followed by death or by a tapering off of acute
> symptoms.

Yes, it's a classic SIR epidemic.

Some diseases, such as some of the STDs (sexually transmitted
> diseases) remain infectious after secondary symptoms diminish or totally
> disappear and, also, physiological damage continues (as in the case of
> syphilis) or becomes more infectious during periodic eruptions (such as in
> the case of herpes II, but is marginally transmissible at other times).
>
> Whether a "recovering" WWI soldier was infectious, I do not know. Soldiers
> could have infected other soldiers, and then died or recovered and thus
> could have been removed from the "contagious pool," but the pool would thus
> have "drifted." In any event not ALL cases came from military and
> military-medical individuals but, also, through certain civilian travelers.
> While the "troops" sped the spread, they were not responsible for spread in
> other parts of the world. (The pandemic is believed to have begun in China,
> spread from their to Russia and Europe, etc., before reaching Spain.
> Nations in the battle zone of WWI did not keep good records (or lost them).
>
I never argued that troops were responsible for the long-distance
spread: indeed, they're unlikely to have done that. However, once the
epidemic reached the troops, it would have spread quickly.


> But, stay with me here, to the making of the point that contagious
> individuals, whether troops, medical personnel, civilians or whomever (sick,
> dying, recovered, carriers, or any combination thereof) brought the
> infection to the western hemisphere, it spread rapidly. Even if the
> soldiers WERE mostly young adult males, it cannot be argued that they came
> into contact ONLY with others of their age group.

I never argued that. But (a) they were mainly in contact with other
soldiers, and (b) they were not in a fit state, because of the other
effects of the war.

<snip>
>
> And, even if it were to be established that the soldiers were the primary
> source of spread at the outset and only exposed other young healthy males
> and young healthy females, my reason from bringing this issue up was not
> to diagnose the nature of the epidemic, but to point out the fact that death
> does not always select "the fittest."
>
> "Survival of the fittest" seems to me to have all the earmarks of a "sound
> bite."
>
Of course it was. You can even find out who coined it, if you search
hard enough.

Your arguments are wrong, simply because you're not using the definition
of fitness that is used in evolutionary biology. One problem is that
much of what you're calling "fitness" is what we would call "condition":
men in their early 20s generally are in better condition that the very
young or very old. But being in your 20s is not a fitness trait:
everyone who reaches that age gains the trait.

Fitness also has to have a (genetic) heritable component, if evoution is
to occur. So, as driving a car is not a heritable trait in that sense
(the extent to whic it is inherited is cultural), so we wouldn't
describe it as a fitness trait.

Where you are right is in seeing that there is not fitness "plan":
anmals don't go around with their fitness stamped on their heads (*).
Instead they reproduce and die at varying rates. The ones with genes
that mean that they reproduce more, or die at a lower rate, will tends
to pass on their genes: hence evolution. We use fitness to quantify
this, i.e. to put a number on the differential rate at which genes are
passed on. This is what fitness tells us: if Hitler used a different
concept to develop his ideas, then OK, he did. But he never worked on
biology, so it's not clear why we should use his definition of fitness
in biology.

Bob

(*) Bonus points will be awarded to those who can point out in what
sense this is not true. It doesn't alter my basic argument, just makes
it more complex.

--
Bob O'Hara
Department of Mathematics and Statistics
P.O. Box 68 (Gustaf Hällströmin katu 2b)
FIN-00014 University of Helsinki
Finland

Telephone: +358-9-191 51479
Mobile: +358 50 599 0540
Fax: +358-9-191 51400
WWW: http://www.RNI.Helsinki.FI/~boh/
Journal of Negative Results - EEB: www.jnr-eeb.org

.

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