Scientists have long wondered what exactly happened in the ninth century A.D., when the flourishing Maya civilization in Mesoamerica fell into what would be a permanent decline, its once-great cities reclaimed by jungle. More recent research revealed the Maya also experienced an earlier collapse, in the second century, about which scientists know even less. In a new study, based on the largest set of radiocarbon dates ever obtained from a single Maya site, a team of researchers argues that both collapses were preceded by similar patterns, as waves of social instability, warfare and political crises swept over the civilization and caused it to deteriorate.

For more than a decade, a team led by researchers from the University of Arizona has been working at the archaeological site of Ceibal in northern Guatemala. After assembling a record-setting 154 radiocarbon dates, the researchers have been able to develop a highly precise chronology that illuminates the patterns that led up to the two collapses that the Maya civilization experienced: the Preclassic collapse, in the second century A.D., and the more well-known Classic collapse some seven centuries later.

Archaeologists excavate the royal palace of Ceibal, which was burned during the Classic Maya collapse in the ninth century.
Archaeologists excavate the royal palace of Ceibal, which was burned during the Classic Maya collapse in the ninth century. (Credit: Takeshi Inomata/University of Arizona)

One of the most dominant civilizations in Mesomerica, the Maya reached their peak around the sixth century A.D., constructing impressive stone cities and making advances in agriculture, calendar-making and mathematics, among other fields. But by A.D. 900, those great stone cities were mostly abandoned. Theories about what caused the Classic Maya collapse have ranged from overpopulation to ongoing military conflict between competing city-states to some catastrophic environmental event, such as an intense drought—or some combination of all of those factors.

The radiocarbon dates from Ceibal, a major Maya center, as well as highly controlled excavations at the site of its ruins, allowed the researchers to trace changing population size, along with decreases and increases in construction. While earlier, more generalized timelines of the Maya civilization have suggested the society collapsed gradually, the new study’s far more precise chronology shows just how complex the process of collapse was.

“It’s not just a simple collapse, but there are waves of collapse,” explained the study’s lead author, Takeshi Inomata, a University of Arizona anthropology professor and archaeologist. “First, there are smaller waves, tied to warfare and some political instability, then comes the major collapse, in which many centers got abandoned. Then there was some recovery in some places, then another collapse.”

Archaeologists excavate a Mayan temple built right before the pre-Classic collapse in the second century.
Archaeologists excavate a temple built right before the pre-Classic collapse in the second century. (Credit: Takeshi Inomata/University of Arizona)

Though it doesn’t completely solve the mystery or break down exactly which destabilizing events triggered the two Maya collapses, the new study marks an important new step in that process, revealing the similarities in the patterns leading up to both. In each case, the waves of collapse began small and grew in intensity, eventually leading the Maya to abandon their city centers.

“It’s really, really interesting that these collapses both look very similar, at very different time periods,” said Melissa Burnham, one of three University of Arizona anthropology graduate students who co-authored the paper. “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.”

Daniela TriadanInomata and his team published their findings in the journal Proceedings of the National Academy of Sciences. In addition to Inomata and his Arizona colleagues, researchers from Ibaraki University, Naruto University of Education and the Graduate University for Advanced Studies in Japan, and Guatemalan archaeologists and students collaborated on the project. The carbon dating was done at Japan’s Paleo Laboratory Company and the Accelerator Mass Spectrometry Library at the University of Arizona.