The Influence of the Environment on the Demographic Decline of the Mayan Civilization

Mayans is a term used to described indigenous people who originated in parts of Mexico and central America, as such the Mayan civilization maybe defined as a society or the culture of the indigenous people (Mayans) who occupied Mexico and Central America in the 16th century. It is believed that the ancient Mayans lived in the Yucatan peninsula (South-East Mexico) from around 2600 B.C. t0 950 A.D when there was a drastic decline in the Mayan civilization. The Mayan were known to be skilled farmers and so they would clear large acres of land to facilitate there farming. There society of driven by a class system, at the top were the priest and nobles, the middle: traders, craftsmen and warriors while at the bottom stood the farmers and slaves. Around 250 A.D the Mayan population began growing exponentially and had reached its peak during the period between 250 A.D and 900 A.D (Classic period) where they inhabited places like Belize, Guatemala, Western Honduras etc. however, around 800 A.D to 950 A.D (Terminal period) there was a major demographic decline as all the large classic sites located in the south were abandoned and this led to a demographic collapse. The Mayan civilization is believed to have collapsed due to human-induced and naturals reasons, that is believed to have collapsed due to socio-political and ecological reasons due to human behavior, however, growing evidence is uncovering where the Mayan Civilization could have collapsed, to a great extent, because of climatic changes or environmental factors. The pages of this essay will then seek to discuss the extent to which environmental factors/climate change is responsible for the demographic decline of the Mayan Civilization during the Terminal Classic Period (800 A.D -950A.D) using paleoclimatic evidence from four different sources; namely the Cariaco basin, Laguna Chichencanab, Puta Laguna and Chaac.

The demographic collapse of the Mayan civilization is believed to have been influenced by human induced sociopolitical and ecological reasons. The Mayan population was a relatively large population and so it was believed that they would have exhausted the resources and it was no longer able to suffice the population as such it resulted in the large classic cities being abandoned. Sociopolitical reasons such as the invasion of outsiders, that is persons who share a different culture than the Mayans; the rebellious action taken by the peasants against the governing body which lead to the overthrowing of the elites in the class system; warfare among inter city states as well as competition with trade alliances which led to the decline of the traditional system of inherited power as well as the failure of the centralized political authority; were all believed to have contributed to the decline of Mayan civilization. In addition to this, ecological reasons such as deforestation which was due to clearing of large acres of tropical forest for farming purposes; soil exhaustion and erosion due to overuse of land for farming and other purposes; water loss, disease, natural disasters and over population which would have resulted in a strain on natural resources; would also have influenced the decline in Mayan civilization.

Although the factors listed above could be an ideal reason for the demographic collapse of the Mayan civilization, there is growing evidence which proves or show that environmental factors or climate change would have contributed to the Mayan civilization decline to a greater extent. The region experiences interchangeable periods of rainfall and droughts which is thought to be controlled by the shifting position of the intertropical convergent zone (ITCZ)- a region which circles the earth, close to the equator where the southern and northern hemisphere trade wind meets causing rainfall, in conjunction the strength and frequency of El Nino events. With reference to Haug, et.al, Scientists believe that during the Terminal period there was a shift in the mean latitude of the Atlantic ITCZ which might have been driven by pacific based climatic variability which led to a prolonged period of drought. With this belief scientist have reconstructed rainfall patterns at four different locations within the Yucatan Peninsula using proxies such as iron, titanium, calcium carbonates, gypsum, oxygen isotopes and cave deposits (speleothem). Scientist collected sediment from the Cariaco basin, an anoxic marine basin located in Venezuela which contained records of iron and titanium. Seeing that the basin is located and positioned in such a way that allows the accumulation of both terrestrial and marine sediments, high concentrations of these chemical elements suggest increased rainfall which would have caused these elements and other materials to be washed down into the basin; low levels/concentration on the other hand suggests reduced rainfall and increased trade winds. The use of the levels of titanium and iron have uncovered three periods of drought, that is during these periods the records of iron and titanium were relatively low. These periods where 810 A.D, 860 A.D and 910 A.D all of which coincided with the demographic collapse of the Mayan civilization. Not only that but during this time the tang dynasty followed the same trend and collapsed during this same period. The periods of drought had put a strain on the resources of the Mayans causing social stress and resulting in the decline in Mayan civilization to some extent.

Laguna Chichencanab is an elongated lake located in Mexico. The sediment core collected from this site contained lighter calcium carbonate rich sediments in between layers of organic matter suggesting there might have been ostracods. The lake water was tested for both heavy and light oxygen isotopes as when evaporation takes place the lighter oxygen isotopes levels are low and when condensation/precipitation takes place the heavier oxygen isotopes increases (as can be seen in figure 1 below) as such in periods of drought, the lake levels will reduce and the ratio of heavy to light oxygen isotope will increase.

The sediment core of Laguna Chichencanab also contained deposits of gypsum suggesting period of dry conditions. The results obtained confirmed similarly to the results of the Cariaco basin that there were periods of drought around the same time the Mayan Civilization had collapsed. The level of gypsum and calcium carbonate is controlled by precipitation/ evaporation ratio as such the amount of gypsum present can determine climatic conditions. The results for Laguna Chichencanab showed that there was an increase in the level of gypsum as well as heavy and light oxygen isotope ratio which suggested drought during this period. The date was confirmed using the radiocarbon date of a seed taken from the height of the sulfur and oxygen isotope values which was dated to be around 893 A.D. which coincides with the terminal period, the period in which there was a demographic decline in Mayan civilization. The Punta Laguna, also located in Mexico showed high levels of calcium carbonate within its sediment core which propose that ostracods and gastropods were present. The results obtained from the Punta Laguna in general where similar to that of Laguna Chichencanab as the level of heavy oxygen isotopes where consistent for both locations. Both locations showed periods of dry climatic conditions that coincided with the terminal period.

Scientist also visited the Tecoh cave located in the northwest region of the Yucatan peninsula where the relationship between rainfall and heavy oxygen isotopes were tested using the most recent bands from a 45cm stalagmite named Chaac. With reference to Burn, the results obtained showed where there was a direct relationship between rainfall and heavy oxygen isotopes seeing that as the level of rainfall increases so does the heavy oxygen isotope levels. The results also illustrated that during the terminal classic period there were periods of droughts which might have contributed to the demographic collapse of the Mayan civilization.

Conclusively, all the paleoclimatic archives produced results illustrating the there were periods of drier climates/ droughts during the Terminal classic period in the Yucatan peninsula. These results also concluded that environmental factors did contribute to the demographic collapse of the Mayan civilization directly and indirectly. As the periods of drought observed would have impacted food production, human health and the environment in general which then led to social unrest, warfare, disintegration of their political system and most important of them all drastic depopulation or abandonment of the large classical cities. So, with that being said environmental factors such as drought played a major role in the demographic collapse of the Mayan civilization.

References

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