One of the world’s great civilisations was forced into terminal decline by successive dry periods culminating in a prolonged drought, according to a study that throws fresh light on the mysterious disappearance of the Maya in Central America around 1,100AD.
Scholars have long wondered about the circumstances that led to the relatively abrupt end of the Maya civilisation which had existed for about 2,000 years and grew to support a population of up to 13 million people at the height of its “classic” period.
Some of the theories about the collapse of Maya society included civil wars or famine brought on by environmental degradation, but the latest study suggests that the underlying reason may have been a lack of rain resulting from regional climate change.
Scientists who have analysed the chemical makeup of limestone columns or stalagmites that formed over 2,000 years on the floor of Yok Balum Cave in southern Belize said the region experienced periods of abundant rainfall and then prolonged drought, which correspond to the rise and fall of Maya society.
“Unusually high amounts of rainfall favoured an increase in food production and an explosion in the population between AD 450 and 660. This led to a proliferation of cities like Tikal, Copan and Caracol across the Maya lowlands,” said Doulas Kennett, professor of anthropology at Pennsylvania State University.
“The new climate data show that this salubrious period was followed by a general drying trend lasting four centuries that was punctuated by a series of major droughts that triggered a decline in agricultural productivity and contributed to societal fragmentation and political collapse,” Professor Kennett said.
“The most severe drought, in the record (from AD 1020 to 1100) occurs after the widespread collapse of Maya state centres and may be associated with widespread population decline in the region. Over the centuries, the cities suffered a decline in their populations and Maya kings lost their power and influence,” he said.
The study of the stalagmites of Yok Balum Cave, published in the journal Science, relied on a radioactive dating technique that is accurate to within 17 years, combined with an analysis of oxygen isotopes that gave estimates of the rainfall over a period of many centuries.
The classic period of the Maya, which started around 300AD, resulted in the building of stone pyramids, the widespread use of written records and the charting of the movements of stars and planets. The population during this period expanded from around 3 million to 13 million, supported by a network of irrigated corn fields.
It is not the first time that climate change has been suggested as a possible cause of the Maya demise. In 2003, scientists studying river sediments in the Cariaco Basin off the coast of Venezuela suggested that a period of prolonged drought may have killed off the Maya.
James Baldini of Durham University, who led the cave monitoring part of the latest study, said that after many years of hardship brought on by a drier climate, the final nail in the coffin appears to be a drought that last the best part of the 11th Century.
“The rise and fall of the Maya is an example of a sophisticated civilisation failing to adapt successfully to climate change,” Dr Baldinin said.
“Periods of high rainfall increased the productivity of Maya agricultural systems and led to a population boom and resource overexploitation. The progressively drier climate then led to political destabilisation and warfare as resources were depleted,” he said.