Scientists at the University of Cincinnati in the United States has revealed one of the reasons for the disappearance of an advanced civilization the Mayans. It turned out that the reservoir of the ancient city of Tikal was contaminated with high levels of toxic substances that could adversely affect the health of the population in times of drought and forced people to leave the settlement. Their findings the researchers presented in a paper published in the journal Scientific Reports.

It is known that the Maya left Tikal in the middle of the IX century ad, but the exact cause of the outcome remains unknown. One of the main roles could be played by a prolonged drought that lasted several decades, from 820 to 870 ad. This made it difficult to access such sources of freshwater, such as lakes and groundwater, with the result that the urban population was forced to rely on a system of reservoirs surrounding Tikal. However, as shown by the authors of the new work, the reservoir was not safe.

The researchers analyzed samples of sediments in the four main reservoirs of Tikal with the help of radiocarbon Dating, mass spectrometry and spectrophotometry. Two tanks were revealed high concentrations of mercury, related to the period from 600 to 900 years BC, and in some samples the content of toxic metal is several times higher than the safe level for fresh water. The source of the mercury could be the colors that Maya is widely used for decoration, architectural ornaments, and ritual purposes.

Maya drank water, which contained not only mercury, but also high concentrations of phosphate, which fell into the reservoir together with food waste and fecal matter. Sequencing of ribosomal RNA extracted from the samples showed that the pollution with organic matter has led to the growth of cyanobacteria (blue-green algae) Microcystis and Planktothrix, which emit potentially deadly toxins. These toxins have a devastating impact on the human body even at low concentrations and resistant to boiling.

Access to contaminated reservoirs were mainly the ruling elite of Tikal. This could have a negative impact on their ability to govern the city. We know that chronic mercury poisoning is associated with metabolic syndrome (although the mechanism of this is not clear), and Dark Sun, one of the rulers of the city, suffered from severe obesity. Because the power of Maya dependent on the ability to provide access to clean water, the credibility of the leaders of Tikal could seriously falter, write the authors. The same scenario is likely implemented in other centers of the Mayan civilization.