Posted on 01/11/2006 1:33:43 PM PST by blam
Megadrought and Megadeath in 16th Century Mexico
Rodolfo Acuna-Soto,* David W. Stahle, † Malcolm K. Cleaveland,† and Matthew D. Therrell† *Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, Mexico and †University of Arkansas, Fayetteville, Arkansas, USA
The native population collapse in 16th century Mexico was a demographic catastrophe with one of the highest death rates in history. Recently developed tree-ring evidence has allowed the levels of precipitation to be reconstructed for north central Mexico, adding to the growing body of epidemiologic evidence and indicating that the 1545 and 1576 epidemics of cocoliztli (Nahuatl for "pest”) were indigenous hemorrhagic fevers transmitted by rodent hosts and aggravated by extreme drought conditions.
The native people of Mexico experienced an epidemic disease in the wake of European conquest (Figure 1), beginning with the smallpox epidemic of 1519 to 1520 when 5 million to 8 million people perished. The catastrophic epidemics that began in 1545 and 1576 subsequently killed an additional 7 million to 17 million people in the highlands of Mexico (1-3). Recent epidemiologic research suggests that the events in 1545 and 1576, associated with a high death rate and referred to as cocoliztli (Nahuatl for "pest"), may have been due to indigenous hemorrhagic fevers (4,5). Tree-ring evidence, allowing reconstructions of the levels precipitation, indicate that the worst drought to afflict North America in the past 500 years also occurred in the mid-16th century, when severe drought extended at times from Mexico to the boreal forest and from the Pacific to Atlantic coasts (6). These droughts appear to have interacted with ecologic and sociologic conditions, magnifying the human impact of infectious disease in 16th-century Mexico.
Figure 1. The 16th-century population collapse in Mexico, based on estimates of Cook and Simpson (1)....
Figure 2. Winter-spring precipitation reconstructed from tree ring data, Durango, Mexico ...
The epidemic of cocoliztli from1545 to 1548 killed an estimated 5 million to 15 million people, or up to 80% of the native population of Mexico (Figure 1). In absolute and relative terms the 1545 epidemic was one of the worst demographic catastrophes in human history, approaching even the Black Death of bubonic plague, which killed approximately 25 million in western Europe from 1347 to 1351 or about 50% of the regional population.
The cocoliztli epidemic from 1576 to 1578 cocoliztli epidemic killed an additional 2 to 2.5 million people, or about 50% of the remaining native population. Newly introduced European and African diseases such as smallpox, measles, and typhus have long been the suspected cause of the population collapse in both 1545 and 1576 because both epidemics preferentially killed native people. But careful reanalysis of the 1545 and 1576 epidemics now indicates that they were probably hemorrhagic fevers, likely caused by an indigenous virus and carried by a rodent host. These infections appear to have been aggravated by the extreme climatic conditions of the time and by the poor living conditions and harsh treatment of the native people under the encomienda system of New Spain. The Mexican natives in the encomienda system were treated as virtual slaves, were poorly fed and clothed, and were greatly overworked as farm and mine laborers. This harsh treatment appears to have left them particularly vulnerable to epidemic disease.
Cocoliztli was a swift and highly lethal disease. Francisco Hernandez, the Proto-Medico of New Spain, former personal physician of King Phillip II and one of the most qualified physicians of the day, witnessed the symptoms of the 1576 cocoliztli infections. Hernandez described the gruesome cocoliztli symptoms with clinical accuracy (4,5). The symptoms included high fever, severe headache, vertigo, black tongue, dark urine, dysentery, severe abdominal and thoracic pain, large nodules behind the ears that often invaded the neck and face, acute neurologic disorders, and profuse bleeding from the nose, eyes, and mouth with death frequently occurring in 3 to 4 days. These symptoms are not consistent with known European or African diseases present in Mexico during the 16th century.
The geography of the 16th century cocoliztli epidemics supports the notion that they may have been indigenous fevers carried by rodents or other hosts native to the highlands of Mexico. In 1545 the epidemic affected the northern and central high valleys of Mexico and ended in Chiapas and Guatemala (4). In both the 1545 and 1576 epidemics, the infections were largely absent from the warm, low-lying coastal plains on the Gulf of Mexico and Pacific coasts (4). This geography of disease is not consistent with the introduction of an Old World virus to Mexico, which should have effected both coastal and highland populations.
Tree-ring evidence, reconstructed rainfall over Durango, Mexico during the 16th century (6), adds support to the hypothesis that unusual climatic conditions may have interacted with host-population dynamics and the cocoliztli virus to aggravate the epidemics of 1545 and 1576. The tree-ring data indicate that both epidemics occurred during the 16th century megadrought, the most severe and sustained drought to impact north central Mexico in the past 600 years (Figure 2; [7]). The scenario for the climatic, ecologic, and sociologic mediation of the 16th-century cocoliztli epidemics is reminiscent of the rodent population dynamics involved in the outbreak of hantavirus pulmonary syndrome caused by Sin Nombre Virus on the Colorado Plateau in 1993 (8,9). Cocoliztli was not pulmonary and may not have been a hantavirus but may have been spread by a rodent host. If true, then the prolonged drought before the 16th-century epidemics would have reduced the available water and food resources. The animal hosts would then tend to concentrate around the remnants of the resource base, where heightened aggressiveness would favor a spread of the viral agent among this residual rodent population. Following improved climatic conditions, the rodents may have invaded both farm fields and homes, where people were infected through aspiration of excreta, thereby initiating the cocoliztli epidemic. The native people of Mexico may have been preferentially infected because they worked the agricultural fields and facilities that were presumably infested with infected rodents.
Figure 3. The winter-spring precipitation totals estimated for each year in Durango, 1540–1548 ...
Ten lesser epidemics of cocoliztli began in the years 1559, 1566, 1587, 1592, 1601, 1604, 1606, 1613, 1624, and 1642 (10). Nine of them began in years in which the tree-ring reconstructions of precipitation indicate winter-spring (November-March) and early summer (May-June) drought (8). But the worst epidemic of cocoliztli ever witnessed, 1545–1548, actually began during a brief wet episode within the era of prolonged drought (Figure 3). This pattern of drought followed by wetness associated with the 1545 epidemic is very similar to the dry-then-wet conditions associated with the hantavirus outbreak in 1993 (Figure 3; [9]), when abundant rains after a long drought resulted in a tenfold increase in local deer mouse populations. Wet conditions during the year of epidemic outbreak in both 1545 and 1993 may have led to improved ecologic conditions and may also have resulted in a proliferation of rodents across the landscape and aggravated the cocoliztli epidemic of 1545–1548.
The disease described by Dr. Hernandez in 1576 is difficult to link to any specific etiologic agent or disease known today. Some aspects of cocoliztli epidemiology suggest that a native agent hosted in a rain-sensitive rodent reservoir was responsible for the disease. Many of the symptoms described by Dr. Hernandez occur to a degree in infections by rodent-borne South American arenaviruses, but no arenavirus has been positively identified in Mexico. Hantavirus is a less likely candidate for cocoliztli because epidemics of severe hantavirus hemorrhagic fevers with high death rates are unknown in the New World. The hypothesized viral agent responsible for cocoloztli remains to be identified, but several new arenaviruses and hantaviruses have recently been isolated from the Americas and perhaps more remain to be discovered (11). If not extinct, the microorganism that caused cocoliztli may remain hidden in the highlands of Mexico and under favorable climatic conditions could reappear.
Acknowledgments This research was funded by the National Science Foundation, Paleoclimatology Program Grant number ATM 9986074.
Dr. Acuna-Soto is a professor of epidemiology on the Faculty of Medicine at Universidad Nacional Autonoma de Mexico. He is particularly interested in the history and environmental context of disease in Mexico.
Actually, the Black Plague (and other terrible infectious plagues) are carried by FLEAS, by the INSECT, the flea.
They are hosts to a parasitic process that lives in their guts and when they bite an animal, they infect the animal. Given the high population of fleas on rodents, then rodents scramble around human habitats and then pass it on.
But, the Black Plague actually originated in Northern and Central Asia, where it was transmitted in the guts of fleas on camels in the import trade from Asia to Europe. And, of course, to rodents after the fleas arrived on the camels, and then to humans in Europe (and eventualy elsewhere).
The hapless rodents simply get to be the method of transmission.
Yes, so I've also read and imagined, particularly after viewing the petrified trees and tree trunks...very large, substantial trees toppled over and petrified where they lay, without the ability to even decay, indicating severe and extreme drought conditions occuring relatively quickly.
Must'a been horrific to experience. Also global, from what I've read as to similar terrible conditions affecting the Mediterranean.
I did read as to what's been determined to have caused the global drought (that's inherent to this article about Mexico's experience of it), but now can't recall. I THINK it is attributed to the wobble of the Earth's orbit around the Sun but can't be certain (memory is foggy about this). There's always the "increased volcanic activity" that causes global atmospheric occlusion and thus, limits what sunlight reaches the planet's surface, then affecting everything else...since the drought was worse on the shared longitude, it seems to indicate, actually, both.
Tangentially...of interest here...the area that was populated at it's height of civilization by the Egyptians was sent into permanent drought (remains so) due to the fact that the Himalayas rose up as a high range during the many centuries of the Egyptians -- and the rising mountain range to their East changed the atmospheric moisture flow on the planet.
Don't these things become endemic over time? I can't say I haven't done a lot of reading on Mexico, but the plague lasted for about 300 years in England, reappearing periodically.
It's easy to see how they do become endemic. And despite that, still no immunity by those who are "local" to the worst of these bugs.
My perspective as to bacteria and viruses in general is that they're all here with us all the time, in that we're all present on the planet simulataneously. It's just a case of when what infects the species and once that occurs, others become infected, also. Containment is nearly impossible with larger populations and certainly with mobile ones.
Like the Black Plague...the "mobility" in place by the trade routes allowed the bug to proliferate among humans outside isolated areas in Asia. And look what happened.
The thing that puzzles me is that if it was an exotic plague, why haven't we seen an outbreak in localized areas like Lassa fever?
Ah! Very interesting and a real bummer. I need a good chunk of cooked beef occasionally.
Well, conditions (all), whatever they are, have to be met inorder for the agent/cause to emerge. You can never tell about these things...sometimes one particularly virulent bacteria can be living amidst one or two populations of insects and their combined populations eventually overtake the other animals' that they prey upon. Perhaps one of the two (or whatever, as an example of changing conditions here) became extinct or is in small population numbers or even hibernate for ten, twenty year cycles due to moisture, sunlight changes, food source, whatever, and, once reduced, can't affect the entire population to the extent that they overtake as to infections their prey/host species'...
A lot of species are not large in populations in any one area globally...from all varieties of life, animal, plant and insect. It's a case of whatever conditions and crowding is required for whatever the bug is or bugs are inorder to proliferate to some intense load that then affects other, larger populations.
Or, it can also have to do with access. Like what populations access what areas for what purpose and interact with what when they do. If some bacterial lives in some deep underground cave and it's only visited once every century, and even then the visitors are not in contact with that bacteria except perhaps on only one occasion, then the aren't infected and don't infect others when they complete their occasional cave visit.
There still are such limited populations in areas that it's surprising...like albino insects found only in one small area on the planet or the brine shrimp remaining from long, long ago when areas of the Southwest and West were under an ocean but are now dry desert.
The bubonic plague outbreak that occured in Colorado and New Mexico a short while ago was found to have started with one fellow who had crawled underneath his house in Colorado to try to retrieve a stranded housecat, and he breathed in some dust that had laid there for a long, long time undisturbed (old rodent droppings in the dust) and became infected quite by random that way. The cat wasn't infected so perhaps it took the guy being face down or cheek down in the dust breathing heavily for a while as he labored there trying to get the cat, inorder to become infected. The cat, sitting above the dirt, wasn't.
But then that guy infected a few others and it soon began appearing in children in New Mexico who were out playing routinely in the dry fields, running around in heavy breathing repeatedly like children at play do.
Same thing with other infectious diseases. It takes a combination of all the necessary things all at once inorder to become infected.
Except with a few horrid airborne bugs that infect nearly any and all who merely breathe in, as with the worst of the hemorraghics. And then bodily fluid contact as with HIV.
But with the plague, "it" was just lying all around the environment for who knows how long and it took an extra dry spell that produced more dust than usual to then be stirred up by heavily breathing humans who got their noses right up next to the dust inorder to become infected this last outbreak (of the plague).
another source of data may have been tax records. I have no specific information on Spanish taxing practices, but after 1066, William the Conqueror commissioned the Doomsday Book, which recorded every person in the conquered area of England, and their property.
Deat and taxes, death and taxes....
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hanta virus is an old plague in the Americas and Asia. It kills off the young, healthy adults leaving behind the oldsters and children.
Hanta virus, however, can kill millions of people in short order and leave civilizations destroyed in its wake.
“Tree-ring evidence, allowing reconstructions of the levels precipitation, indicate that the worst drought to afflict North America in the past 500 years also occurred in the mid-16th century, when severe drought extended at times from Mexico to the boreal forest and from the Pacific to Atlantic coasts.”
That must be a lie!!! There were no gus-gussling CO2 belching SUVs criss-crossing the moutains, plans, valleys or rivers of North American and Mexico at the time!!!; ergo - impossible for such a drouhgt to occur, such things ONLY can happen when human’s cause them to!!!!!! LOL
The tree record now extends back about 10,000 years in the past. They have detected some serious worldwide events in our past.
I was expresssing a bit of sarcasm and forget to my /sarc label at the end
OF COURSE extreme weather changes have occurred, naturally, in the past
humans do not usually stop and realize that in terms of “earth history” their personal experience is infintessimally small and all of human history not a great deal greater
Mike Baillie is Professor of Palaeoecology at Queens University, Belfast, Northern Ireland. He is an authority on tree rings and their use in dating ancient events (every year, a tree adds a "ring" to its trunk as it grows - good years are represented by thick rings while bad years are represented by thin rings). He conducted a complete (and continuous) review of annual global tree growth patterns over the last 5,000 years and found that there were five major environmental shocks that were witnessed worldwide. These shocks were reflected in the ring widths being very thin. Wanting to know more, he turned to human historical records, and found that the years in question (between 2354 and 2345 BC, 1628 and 1623 BC, 1159 and 1141 BC, 208 and 204 BC, and AD 536 and 545) all corresponded with "dark ages" in civilisation
Interesting article, thanks for posting.
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