New clues to collapse of Maya civilisation uncovered

Using the largest set of radiocarbon dates ever obtained from a single Maya site, archaeologists have developed chronology patterns that may explain what led to the collapse of the ancient civilisation.

Scientists have long puzzled over what caused the Classic Maya collapse in the ninth century AD, when many of the ancient civilisation's cities were abandoned.

More recent studies showed that the Maya also experienced an earlier collapse in the second century AD - now called the Preclassic collapse - that is even more poorly understood.

Scientists from the University of Arizona in the US suggest that both collapses followed similar trajectories, with multiple waves of social instability, warfare and political crises leading to the rapid fall of city centres.

The findings are based on a highly refined chronology using an unprecedented 154 radiocarbon dates from the archaeological site of Ceibal in Guatemala.

While more general chronologies might suggest that the Maya collapses occurred gradually, the new, more precise chronology indicates more complex patterns of political crises and recoveries leading up to each collapse.

"What we found out is that those two cases of collapse (Classic and Preclassic) follow similar patterns," said Takeshi Inomata, a professor at UA College of Social and Behavioural Sciences.

"It's not just a simple collapse, but there are waves of collapse. First, there are smaller waves, tied to warfare and some political instability, then comes the major collapse, in which many centres got abandoned. Then there was some recovery in some places, then another collapse," said Inomata.

Using radiocarbon dating and data from ceramics and highly controlled archaeological excavations, the researchers were able to establish the refined chronology of when population sizes and building construction increased and decreased at Ceibal.

"It's really, really interesting that these collapses both look very similar, at very different time periods," said Melissa Burham, graduate student at UA.

"We now have a good understanding of what the process looked like, that potentially can serve as a template for other people to try to see if they have a similar pattern at their (archaeological) sites in the same area," Burham said.

"Radiocarbon dating has been used for a long time, but now we're getting to an interesting period because it's getting more and more precise," said Inomata.

"We're getting to the point where we can get to the interesting social patterns because the chronology is refined enough, and the dating is precise enough," he said.

The study appears in the journal PNAS.