Posted by: Johan Normark | May 18, 2009

Influenza pandemics, densely packed people and a field season in peril

This time of the year is when many non-Mexican (primarily American or Canadian) archaeological projects working in Mexico is preparing for the summer field season when universities close down. It is not the ideal season to work since it is the beginning of the rainy season. This year there is yet another problem: the swine flu.

For my current research I need to get acquintaed with literature on sustainability so I recently read an edited book by Alf Hornborg and Carole Crumley called “The World System and the Earth System: Global Socioenvironmental Change and Sustainability Since the Neolithic” (2007). Chapter 19 includes an article by Alfred Crosby, Professor Emeritus of History, Geography, and American Studies at the University of Texas at Austin. Like some of his books, this article is about “infectious diseases as ecological and historical phenomena, with special reference to the influenza pandemic of 1918-1919.”

The basic argument in the article is that earlier pre-agrarian humans were small in numbers, geographically dispersed and they were epidemiologically diverged. These people solved problems by moving when there was a food shortage, drought, or when diseases appeared. The diseases that we associate with parasitic animals were far fewer since people had no (or few) permanent dwellings. Crosby (p. 281) says that “humanity was protected against many infections not so much by genetically acquired immunological defenses as by their small numbers and movements. Humanity had, vis-à-vis infection, hedged its bets: a few thousand folks over here with this infection, a few thousand over there with that infection, and a minimum of contact between the two groups, leads to no pandemics for the same reason that you can’t have a forest fire without forest. Humanity was not genetically prepared for the environment that it started creating ten or so thousand years ago.”

It was when farmers began to live close to animals in large concentrations and elites began to crave exotic commodities from far away that epidemics began to show up and spread across great distances. To quote Crosby (p. 282): “by sharing environments with animals in order to utilize their services, Old World peoples found themselves also sharing diseases with them. Hunters and gatherers live among animals but live intimately with few.”

Flu is often associated with the domestication of birds and pigs. Europe has been the most diseased area, particularly from the age of the explorers when “Western Europe’s ships created the first “globalized” disease pool” (p. 283). The Americas before the European conquest had far fewer domesticated animals and hence had no pandemics. This all changed with Columbus. Mexico is now singled out as the area where this particular version of “swine flu” began and the first pigs were introduced by the Spaniards (although peccaries do exist in Mesoamerica, they were never domesticated). It is hardly surprising that the mega metropolis Mexico City is where the first cases were documented.

Should I blame the pigs or the densely packed assemblages of people that we call cities for the risk of not having a field season this year?



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