Medieval poop samples could help researchers understand our intestinal health today — and point to how dietary changes over time contribute to bowel disease, allergies and obesity, a new study revealed.
The study, published Monday in the journal Philosophical Transactions of the Royal Society B, details research conducted in Jerusalem, Israel, and the Latvian capital of Riga.
Researchers examined 14th and 15th century latrines from both cities in order to compare a modern microbiome — composed of the trillions of microorganisms including bacteria, fungi, parasites inside our bodies — with that of our ancestors, according to a press release.
“If we are to determine what constitutes a healthy microbiome for modern people, we should start looking at the microbiomes of our ancestors who lived before antibiotic use, fast food, and the other trappings of industrialization,” one of the researchers, Dr. Piers Mitchell of Cambridge University, said in the release.
In order to make sure the scientists were actually examining medieval excrement, the researchers needed to determine the differences between the microbes that form in the stomach compared to those typically found in soil, CBBC Newsround reported.
Archaeologist Susanna Sbin, a doctoral alumna of the Max Planck Institute for the Science of Human History in Germany, compared the latrine DNA to those from other sources — including the guts of industrial and hunter-gatherer populations, according to the release.
“We found that the microbiome at Jerusalem and Riga had some common characteristics,” Sabin said. “They did show similarity to modern hunter gatherer microbiomes and modern industrial microbiomes, but were different enough that they formed their own unique group. We don’t know of a modern source that harbors the microbial content we see here.”
“A growing body of evidence” links changes in the human microbiome to many modern conditions including inflammatory bowel disease, allergies and obesity, the study authors found.
But researchers say they need to dig deeper into that evolution.
“We’ll need many more studies at other archaeological sites and time periods to fully understand how the microbiome changed in human groups over time,” said Kirsten Bos, an ancient bacterial DNA specialist, also of the Max Planck Institute. “However, we have taken a key step in showing that DNA recovery of ancient intestinal contents from past latrines can work.”
