Two Sewage Pool Stories: DNA Reveals Intestinal Health in Medieval Europe and the Middle East

A new study published this week is the first attempt to characterize the microbial diversity of ancient intestinal contents from two medieval toilets, using methods of ancient bacterial detection pioneered in past epidemic studies. Is shown. The findings provide insights into the microbiome of the pre-industrial agricultural population. This may provide the context that is highly needed to interpret the health of the modern microbiome.

Over the years, scientists have noticed that people in industrial societies have significantly different microbiomes compared to hunter-gatherer societies around the world. From this, ever-increasing evidence links our microbiome changes to many diseases in modern industrialized nations, including inflammatory bowel disease, allergies, and obesity. Current research helps characterize changes in the gut microbiome and emphasizes the value of ancient toilets as a source of biomolecular information.

Ancient Gut Microbiome: Exploring the Gut of History

Piers Mitchell of the University of Cambridge specializes in intestinal content in people of the past through analysis of abnormal substrates. By observing the contents of archaeological toilets and dry feces under a microscope, he and his team learned a lot about the intestinal parasites that plagued our ancestors.

“Microscopic analysis can show the eggs of parasites that lived in the gut, but many microbes in the gut are simply too small to see,” commented Mitchell. “If we want to identify what constitutes a healthy microbiome for modern humans, we need to start looking at the microbiome of our ancestors who lived before the use of antibiotics, fast food, and other industrialization traps.”

Kirstembos, an expert in ancient bacterial DNA at the Maxplank Institute for Human History Sciences and co-leader of the study, was initially skeptical of the possibility of investigating the contents of a long-broken toilet.

“Initially, it was unclear whether the molecular features of the intestinal contents would survive in the toilet for hundreds of years. Much of the success in ancient bacterial recovery to date comes from calcified tissue such as bone and tartar. It was done. Preservation conditions. Still, I really wanted the data here to change my view, “says Boss.

The team analyzed medieval toilet deposits in Jerusalem and Riga, Latvia, in the 14th and 15th centuries AD. The first challenge was to distinguish between the bacteria that once formed the ancient intestines and the bacteria that were introduced by the environment. This is an unavoidable result of working with archaeological materials.

Researchers have identified a wide range of bacteria, archaea, protozoa, parasites, fungi, and other organisms, including many taxa known to inhabit the intestines of modern humans.

“Toilet certainly seems to be a valuable source of information for both microscopic and molecular information,” the boss concludes.

There is no modern match in the ancient microbiome

Susanna Sabin, a PhD graduate of MPI-SHH who co-led the study, compared DNA in toilets with DNA from other sources, including microbiomes, wastewater and soil from industrial and foraging populations.

“We found that the Jerusalem and Riga microbiomes have some common characteristics. They are similar to the modern hunter-gatherer microbiome and the modern industrial microbiome, but have their own group. It was so different that it formed. I don’t know the modern sources. It contains the microbial content found here. “

The use of toilets, which are mixed with feces of many people, has enabled researchers to gain unprecedented insight into the microbiome throughout the community.

“These toilets provided us with more representative information about the pre-industrial population of these regions than individual fecal samples,” explains Mitchell. “Combining light microscopy with evidence from ancient DNA analysis can identify the incredibly diverse organisms found in the intestines of ancestors who lived centuries ago.”

Despite the promise of this new approach to investigating microbiomes, challenges remain.

“More research is needed at other archaeological sites and periods to fully understand how the microbiome has changed over time in groups of humans,” says Boss. “But we have taken an important step in demonstrating that DNA recovery of ancient intestinal contents from past toilets works.”