Re: diseases and immunity

Philip Deitiker (
Sun, 14 Jul 1996 23:44:14 GMT

Joel and Lynn Gazis-Sax <> wrote:

>* One can see a pattern in these deaths: they aren't all over Europe,
>but hit specific areas. Other areas are spared, until later. When
>the big plagues hit again, they hit towns that have not suffered yet
>or cities, like London, which are receiving steady streams of fresh
>blood from the countryside. These people didn't bring the plague
>with them: they caught it when they arrived because their genes
>made them more susceptible. The less movement of a population, the more
>resistance it develops to these diseases.

>* The "superior hygiene" of the Europeans has been brought up as an
>explanation for the differences in immunity levels. The opposite may
>be the case. First, inferior hygiene made the Europeans susceptible
>to more diseases than the Native Americans during these many centuries.
>The general slovenliness of Europeans (note I am of European descent)
>definately hurt in the short run, but helped them in the long run by
>weeding out the weaker people. If I am not mistaken, the Black Death
>never really killed people in America like it did in Europe.

Using the black death as an example does and doesn't fit the core
idea, there were other technologies that began to evolve (or reevolve
as some would argue) in european cities and were neccesarily
progressing as these cities grew. More to say on anti-disease
improvisations for black death but not germane to the issue for the
reasons you mentioned above.

>* Another hygienic factor that was apparently not the fault of the
>Europeans themselves was a shift in what kind of rats infested their
>houses. During the Middle Ages, the black rat was endemic to Europe.
>These rats carried the fleas that were the source of the Black Death.
>Later, in about the 16th century, brown rats began pushing the black
>rats out of their niche. Brown rats were less likely to carry the kind
>of flea that carried the Black Death. Finally, the house rat replaced
>the brown rat and incidents of plague declined even more.

>* Even as incidents of plague continued to hit cities throughout Europe,
>the numbers of those dying dropped. In one of the last cases of plague,
>in Marseilles (18th century), 50,000 people died. The plague failed to
>spread over Europe as it had before. Fatalities in Italian outbreaks also
>dropped as Italians apparently began to be composed more and more of people
>who possessed greater resistance to the disease.

>* Another interesting statistic that comes out in looking over several
>chronologies is that in 1505, the population of New Spain was over
>11 million people. Ten years later, it had around 6 million and ten
>years later only one million people. Reports of epidemics were rife
>during this period, which matched the period of first contact and
>conquest of Mexico.

How much of the loss of life was due to disease and aggresion, how
long did it take for the native populations to rebound. If I loosely
take the population of mexico today and estimate that 2/3 of gene
originated from native american I have a population of about 70
million people. From that 1 million the population must have grown a
whole bunch. Is it fair to not include other reasons for the decrease
in population.
I seriously doubt the population of endemic americans in mexico
every dropped to 1 million.

>Conclusions? The chronologies tend to support the following conclusions:

>* That there were more people alive in the Roman Empire than there were
>in subsequent periods of time up to the mid-18th century.

And you might describe how these various diseases found their way to

>* That Europeans were exposed to many infectious diseases at an earlier
>period than the peoples of the Americas.

>* That this exposure weeded out those less able to withstand the diseases
>and caused European populations to become more resistant to them.

>* That improvement of hygiene (a product of the germ theory of disease --
>not popular until the late 19th century) was less a factor than a
>switch in the variety of rat which infested European households.

Again only if you focus on the black plaque, there were other diseases
particulary those in cities which created epidemics and traveled
without intermediating vectors.

>* That populations in the Americas dropped up to 90% or more when Europeans
>brought their diseases with them. (Note that African slaves also brought
>diseases with them -- things like Yellow Fever and Malaria which decimated
>American cities from time to time until the mosquito link was found!)

Again, you assume all dimunition was due to disease.

There are malarial types endemic to south america. Note that the south
americans may be less adversley affected by the tropical imports as
opposed to europeans, the loss of life in europeans was probalby as
high or higher relative to the endemic populations in some
this neither adds of detracts from the total argument.

>We see nothing more than an evolutionary process at work.

That's right, evolution of immunity and aggression. nobody argued
evolution wasn't at work, the argument was over mechanism. Since you
done such a wonderful job a reviewing the data, in those populations
of new spain identify the proportion of the 10 million lives lost
which are due to disease and aggression. Does the data explain the
amazing recovery in the population?

> Good science
>requires that we measure only that which can be measured and not try
>to invent explanations which suit our personal whims and prejudices.

Also requires thorough data. And we can't assume that those spanish
did not have their own whims and prejudices.

> And
>most of us will be fine until a new infectious disease appears, one for
>which the majority of us have no resistance for.

>From a general perspective I agree with most fundemental arguments. As
for the hygeine issue I must add that by improving hygeine in europe
and not having either on the transatlantic passage or in the new world
was also a negative for europeans arriving also a negative for those
who were exposed to them. OTOH, I must say that in c. 100 rome, or
16th century Paris or London, without some type of hygeine (fecal/oral
separation in water supplies) you cant really form gigantic permanent
settlements, these technolgies were in development.

Secondly, you state the huge loss of life in 'New Spain' as being the
result of disease, even if you are correct and I think the decline is
multiparametric, the population rebounded in this region much faster
than in other areas and this does deserve some attention. Are we
comparing the loss of life from one or many simultaneous diseases and
also aggression and social changes (compaction) if so then 90% decline
over 20 year period isn't so bad. Mary was making the point that on
some islands 90-100% died of a single disease. Take into consideration
say 3 epidemic diseases and scientifically speaking there is a huge
descrepancy in _survivability_ per disease. This must be considered.

Finally, the conquerers most certainly intervened in some of the
post-disease repopulation, to ignore this would be very revisionist,
despite your conclusions I think you need to explain why certain
groups rebounded faster than others, why the size of certain endemic
groups sizes correlates more with remnant territory size than
epidemic waves.

The reason I jumped into this is because many arguements made, on
both sides, seemed biased, now that hard figures are coming forward
the data showed my skepticism to be correct. A little more data, and I
will bow out of this rather amusing debate.