More than 15 years after its discovery, the Midnight Terror Cave in Belize still leaves clues to more than 100 people who were sacrificed to the Mayan rain god more than a millennium ago.
Used for burial during the Maya Classic Period (AD 250 to 925), the cave was named by local residents who were called to rescue a wounded thief in 2006. A three-year excavation project by California State University, Los Angeles (Cal State LA) professors and students have concluded that the more than 10,000 bones found in the cave represent at least 118 people, many of whom had evidence of trauma inflicted around the time of death.
To delve deeper into the victims’ final moments, the latest research doesn’t look at the bones, but instead at their mouths, examining the calcified plaque from their teeth known as calculus. The study, published Sept. 20 in the International Journal of Osteoarchaeology (opens in new tab)described curious blue fibers sticking to the teeth of at least two of the victims.
Lead study author Amy Chan, now an archaeologist working in cultural resource management, began her analysis of the Midnight Terror Cave teeth as a graduate student at Cal State LA, where she was interested in learning more about the dental health of the victims, she said to Live Science by email.
“After finding minimal cases of dental pathology, I became interested in determining what foods the victims consumed,” she said.
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Tartar can preserve microscopic pieces of food that someone ate — such as pollen grains, starches and phytoliths, which are mineralized parts of plants — so Chan scraped the remains from six teeth and sent them to study co-author Linda Scott Cummings (opens in new tab), president and CEO of the PaleoResearch Institute in Golden, Colorado. Scott Cummings found that the samples contained mostly cotton fibers and that several of them were dyed bright blue.
“Finding blue cotton fibers in both samples was a surprise,” Chan said, because “blue is important in Mayan ritual.”
A unique “Mayan blue” pigment has been found elsewhere in Mesoamerica, where it appears to have been used in ceremonies — especially to paint the bodies of sacrificial victims, Chan and colleagues wrote in their research paper. These blue fibers have also been found in an agave-based alcoholic drink in burials at Teotihuacan, an archaeological site in present-day Mexico.
But Chan and her team offered another explanation for the fibers found on the teeth: perhaps the victims had cotton towels in their mouths, possibly from the use of gags leading up to their sacrifice. If victims were held for extended periods of time, their tartar may have incorporated the blue fibers.
“Interestingly, they found colored fibers in tartar,” Gabriel Wrobel (opens in new tab), a bioarchaeologist at Michigan State University who was not involved in the study, told Live Science via email. “Many researchers think numeracy only reflects diet, but this study is a great example of how much more information can be learned.”
Claire Ebert (opens in new tab), an environmental archaeologist at the University of Pittsburgh who was not involved in the study, told Live Science via email that she was “skeptical” that the blue fibers came from clogs. However, she noted that tartar studies are important because “they can be used to look at other aspects of Maya life, ranging from ritual to domestic.”
An expanded study including both elite and non-elite people would be useful “to see if the pattern can also be detected” or if “other explanations for the presence of fibers might be more logical,” Ebert said.
Chan and her team agree that their study, although it provides the first evidence of blue fibers in the tartar of Mayan individuals, has some limitations. First, the rate at which plaque forms and hardens varies depending on the type of food consumed and a person’s physiology, so researchers cannot know for sure when the fibers were trapped. Also, very few teeth of the Midnight Horror Cave victims had tartar, which limited the team’s analysis.
“Future studies will provide a broader context for interpreting these data,” the researchers wrote in their study.