CAMPECHE, MEXICO—While studying the water supply system for the Maya city of Uxul, archaeologist Nicolaus Seefeld of Germany’s University of Bonn discovered a 1,400-year-old mass grave containing the remains of 24 people who had been decapitated and dismembered. The body parts had been placed in an artificial cave used as a water reservoir. Scientists were able to determine the age and sex of 15 of the individuals, including 13 men and two women. They suffered from malnutrition and had lost teeth to decay. Some of the teeth had been adorned with jade inserts—usually interpreted as a sign of high social status. Analysis of the isotopes in the bones could indicate if those individuals were part of the local population or if they came from another region. “However, the discovery of the mass grave proves that the dismemberment of prisoners of war and opponents often represented in Maya art was in fact practiced,” said Nikolai Grube, head of the excavation project.