Two new studies recently published examine the possible causes of the Mayan Empire, which flourished in southern Mexico and Central America until about A.D. 900.

One of the studies was published in the journal Proceedings of the National Academy of Sciences and stated that the Mayans themselves contributed to the downfall of their own empire. Meanwhile the other study, published in the journal Geophysical Research Letters, stated that natural causes brought on by human activity were responsible for ending the Mayans.

The fall of the Mayans has been widely disputed, but most researchers can agree that drought likely played a role, being prefaced by the expanding Mayan empire.

The Mayan's expansion of cites and farmlands led to widespread deforestation. By removing the jungle canopy there was no natural counter to the onset of drought, according to researchers, who used climate-model simulations to see how much deforestation was responsible for the drought.

"We're not saying deforestation explains the entire drought, but it does explain a substantial portion of the overall drying that is thought to have occurred," Benjamin Cook explained, the study's lead author and climate modeler at Columbia University's Lamont-Doherty Earth Observatory and NASA's Goddard Institute for Space Studies.

The results of climate simulations showed that when deforestation was at its maximum, it could account for up to 60 percent of the drying, according to a study published in the journal Geophysical Research Letters.

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But other researchers are certain that it was a combination of factors and not one isolated incident that led to the end of the Mayan empire.

"The ninth-century collapse and abandonment of the Central Maya Lowlands in the Yucatán peninsular region were the result of complex human-environment interactions," researchers said in a study published in the journal Proceedings of the National Academy of Sciences.

"The old political and economic structure dominated by semidivine rulers decayed. Peasants, artisan-craftsmen, and others apparently abandoned their homes and cities to find better economic opportunities elsewhere in the Maya area," researchers added.