When Cambridge University began renovating a museum in 2017, it discovered the remains of dozens of medieval monks. Dating back to 1290, many skeletons still sported the weathered belt buckles, the corroded remains of the friar’s burial vestments. They also showed evidence of something much more insidious: the eggs of parasitic worms that potentially wreaked havoc on the friars’ intestines while they were alive.
Although these men lived a much healthier existence than city citizens outside their community, they were much more likely to be plagued by parasites, a new study reveals. Your gardening practices may be to blame.
In medieval Cambridge, many citizens subsisted in squalor, living alongside livestock in cramped cottages and dumping household excrement into communal holes in the ground called cesspits. The city’s Augustinian friars lived the high life by comparison. Within the walls of the convent, the gardens produced fresh produce and the latrines were secluded. Many convents were even equipped with running water systems—a luxury absent even from aristocratic households of the time—to allow the friars to wash their hands. Like many aspects of their lives, their focus on hygiene brought them closer to God.
This may be why the friars often outlived the commoners. But no one had looked closely at whether the friars were less susceptible to worms and other parasites, a common scourge of the time.
So Piers Mitchell, a paleopathologist from Cambridge, and his colleagues turned to the trove of friar skeletons that had turned up on their territory. To determine whether the remains had been affected by parasites such as roundworms and waterworms, which can cause severe damage to the digestive tract and even stunted growth in extreme cases, the researchers collected sediment around of the pelvis of 19 skeletons dated from the 13th and 14th centuries. .
As a control, they took samples from the friars’ skulls and feet, body parts that shouldn’t have any signs of intestinal parasites. They also collected similar samples from 25 non-monastic skeletons buried at the same time in a rural parish a kilometer away from the convent ruins. This parish cemetery served a predominantly lower-class congregation between the 12th and 14th centuries.
Back in the lab, the team put the samples under a microscope to look for the remains of intestinal intruders. The parasitic worms themselves rotted centuries ago. Instead, the researchers sifted through the samples for microscopic worm eggs, which can persist for centuries in the sediment.
Almost 60% of Cambridge monks were infested with intestinal worms, the team reports today at International Journal of Paleopathology. They were almost twice as likely to be infected by parasites as their non-monastic neighbors.
Ironically, the friars’ better hygiene may be to blame, Mitchell believes. Since they collected their excrement in the latrine rather than throwing it into pits, it is possible that the clergy recycled their own waste (or bought it from the townspeople) as manure for their gardens.
Mitchell notes that roundworms lay their eggs in human feces, so eggs from the gardens could easily make their way to produce and then into the friars’ stomachs. As the worms hatched and wriggled through the friars’ digestive tracts, they would have caused abdominal pain and stressful bowel movements. And as the worm-infested friars retreated to the latrine block, they helped disperse the next generation of worm eggs into the monastery’s supply of fresh manure.
Less is known about the dung practices of the city’s lower classes. But without access to latrines, they may have been less likely to use human excrement for their gardens.
Not all parasitologists agree, however, that the structures that pocket the friars’ pelvis are medieval worm eggs. Karl Reinhard, an archaeoparasitologist at the University of Nebraska, Lincoln, who studies intestinal parasites preserved in the guts of mummies, notes that many eggs the team examined lack the protective shells common in roundworms. “There are many oval structures in the fungal and botanical world that may be parasite egg counterfeiters in archaeological contexts.”
However, intestinal parasites are common in medieval deposits, according to the Cambridge researchers. Skeletons from this period show signs of being ravaged by a variety of tapeworms, trematodes and single-celled protozoa that cause dysentery.
Although the remains of the friars are centuries old, Mitchell believes the message of this find is timeless: “Don’t be the friar who fertilizes your lettuce with your own feces.”