Page 187 - Encyclopedia Of World History Vol IV

1488 berkshire encyclopedia of world history

new diseases, capable of propagating themselves in enough populations of susceptible persons had accu-
diverse climates, to find a niche among still scant popu- mulated in rural hinterlands and smaller cities.
lations of foragers. Crop failure and famine could also provoke outbreaks
As people settled down and lived in fixed abodes how- of disease, and new infections continued to appear in
ever, germs were able to move from one human host to new locations from time to time, sometimes with sudden
another far more easily than before.When human feces and severe consequences for large populations.The most
accumulated around dwellings, for example, people drastic new disease exposure after those of the second
could become infected with intestinal diseases through and third centuries CE, came after 1346, when bubonic
drinking polluted water or through person-to-person plague—the dreaded Black Death—ravaged Europe, the
contact with someone who was already infected.Villag- Muslim world, and China, killing up to a third of the
ers overcame this increased exposure to intestinal dis- population during its first onset and recurring thereafter
eases partly by marrying early and giving birth to numer- at irregular intervals down to the time when antibiotics
ous children, but mainly by developing greater resistances made it easily curable in the 1940s.
in their immune systems. Sporadic die-off from infectious disease resembled
The same was almost equally true of the next intensi- die-off from outbreaks of violence, and the two often
fication of lethal infection, arising through transfers of peaked simultaneously. In fact most war casualties came
herd diseases from domesticated animals to humans.The from disease and not from wounds until after 1900,
most formidable of these infections were viral, and sur- when preventive vaccines reduced soldiers’ risks of infec-
vivors developed resistances that lasted a lifetime. Dis- tion to comparatively trivial proportions. It is also true
eases of childhood, such as chicken pox, measles, and that military formidability and intensified exposure to
mumps, only strike once and can only survive among rel- infectious diseases became twin instruments whereby civ-
atively large populations living in close enough contact ilized societies were able to subdue neighboring popula-
to permit the virus to find an unending sequence of sus- tions and incorporate survivors into their expanding
ceptible hosts. In modern times, it took a population of domain. Unfamiliar infections devastated previously
about a quarter of a million persons for measles to keep isolated populations over and over again within the
going, for example. Cities and all the coming and going Old World and, after l500, even more drastically in
connected with trade, tax collection, and governmental the Americas and other transoceanic lands, where resis-
administration were needed to sustain such viruses. tances were totally lacking to the whole array of diseases
These diseases therefore became characteristic of civilized by then familiar in Eurasia and Africa.
societies in Eurasia, but not in the Americas, where Initial die-offs when Europeans began to settle the
domesticated herds of animals were absent, so herd dis- Americas were total on many Caribbean islands, and
eases could not make the leap to human hosts. among some mainland peoples as well. Over larger
Exactly when and where different herd infections first regions survival proved possible as resistances built up
established themselves among humans is unknown. But among native Amerindians; but not before their societies
when trading contacts began to link Chinese, Indian, and indigenous religious and political organizations had
West Asian, and Mediterranean peoples together, lethal been destroyed by disease-experienced Europeans and
viruses—most notably smallpox and measles—spread Africans imported as slaves. Drastic redistribution of
across the Old World. They provoked heavy die-off in populations and cultures throughout the globe resulting
both the Roman and Chinese empires in the second and from the ravages of infectious disease among previously
third centuries CE. Thereafter these diseases remained isolated populations still continues on remote Arctic
precariously in circulation in a few large urban centers, shores and in the Amazon jungles. It profoundly altered
and sporadically flared up into epidemics when large the population of whole continents and innumerable