As is widely known, the Mayan people saw a significant loss in population starting around AD 770. There is no conclusive evidence indicating one specific cause of this collapse; most likely, it was a combination of several contributing factors. Centuries later, Mesoamerica faced another widespread population decline in the 1500s. Again, it is nearly impossible to pinpoint what caused this occurrence. The data indicate that disease may have been a causative factor in the Maya collapse, though the identity of the disease itself is a mystery due to the lack of preserved human remains. However, data indicates that there were extended droughts occurring in the years leading up to both of these crashes in population. In addition, there is evidence that the sixteenth century population decline was caused primarily by a hemorrhagic fever that was likely associated with the drought. Because of the similarities between the long drought and following population decline, it is possible that an increase in disease similar to what was seen in 16th century Mesoamerica was also the cause of the collapse of the Mayan people.
The Maya were once a highly successful and advanced people with a number of large cities and an impressive population. They developed their culture over several thousand years leading up to their most prosperous years from AD 250 to 750, which is known as the Classic Period. Then, around AD 770, the Maya culture began to disintegrate; towns and cities were vacated, the production of fine art declined, and trade and construction decreased. The great city of Teotihuacan also fell during this time period, known as the Terminal Classic. Other large cities were soon deserted as well; this trend continued until almost all the major city centers were abandoned by AD 950. There is no evidence supporting any single explanation for this dramatic population loss. The severe decrease may have been caused by decline in agriculture, social or political issues, or natural causes such as drought to name a few. Whatever the cause, it is certain that the Maya civilization had collapsed.
Several hundred years later, the same region witnessed another significant loss in population. While there were, again, several possible factors influencing this decline, there is one explanation for a great majority of the deaths that occurred during the 1500s. A hemorrhagic fever, which was called Cocoliztli, ravaged through Mesoamerica. Two epidemics of Cocoliztli, occurring in 1545 and 1576 respectively, killed a total of 13 million people. The origins of this devastating disease remain unknown, but it is known that it worked quickly and effectively, as it was almost always fatal. Symptoms ranged from headache and fever to dementia, nodule formation, and bleeding from all orifices before eventual death. Interestingly, the more severe symptoms of Cocoliztli only affected the native inhabitants of Mesoamerica; it was this population that faced such high mortality. This deadly disease resulted in a population collapse that was comparable in severity to the occurrences of the Terminal Classic Period.
While there are obvious differences between the collapses during the Terminal Classic Period and the sixteenth century, both occurred during similar environmental conditions. Evidence indicates that during the years before both population declines, the region was facing a period of severe drought. As indicated by data from tree rings, a long drought happened from AD 700 to AD 900 that stretched as far north as the Southwestern United States. The tree ring data also revealed that there were some periods of rain during the drought. There were similar brief wet periods during the drought of the sixteenth century; these occurred around 1545 and 1576, which coincides with both of the Cocoliztli outbreaks. The deadly outbreaks seem to be a result of the conditions of a wet period occurring during a drought.
While there is no full explanation for either the Terminal Classic or sixteenth century population collapses, there is data to show that the drought conditions during both times were very similar. Both declines were set during long, severe droughts that were broken up by short, wet periods. The specific conditions that resulted in the Cocoliztli outbreaks in the sixteenth century were therefore also present during the collapse of the Maya. The repetition of these similar and unique conditions therefore seems to indicate the possibility of Cocoliztli outbreaks during the Terminal Classic Period, which may have contributed to the significant population decline. Given the millions of deaths that the fever outbreaks caused in a relatively short span, it does seem possible that Cocoliztli could have also caused the similarly rapid and severe loss of the Mayan people. Although we would need more sound evidence to be certain, an outbreak of the deadly Cocoliztli disease may provide an explanation for the collapse of the Mayan civilization.