PArasites are usually a fairly private affair. And, for that matter, defecation. So perhaps never in their wildest dreams did the people of Loma San Gabriel (in what is now Mexico) who answered the call of nature in a cave more than 1,000 years ago imagine that future humans would rummage through their droppings for clues.
Feces are open window into many other organisms that live in our bodies, from beneficial bacteria to harmful parasites. The genetic material of these other life forms enters the world through our own products. Thus, scientists can and do go looking for familiar (or unfamiliar) DNA sequences for a number of reasons. (Wastewater treatment plants, for example, have been key sites for monitoring local COVID-19 surges.)
But despite the fact that DNA is currently rich in information, it, like most biological materials, tends to degrade over time. So finding such small traces of pathogens in ancient excrement can be challenging. The researchers behind new researchpublished in PLOS ONEused PCR testing and additional sequencing to see what they could find in a collection of 10 different paleofecal samples collected from La Cueva de Los Muertos Chiquitos in the Rio Zape Valley in Mexico. The remains were deposited around 725-920 AD.
It turned out that pathogens and parasites were extremely common among the people living in the area at the time. For example, the vast majority of samples showed that a human defecator was harboring coliand six of the 10 studied were infected with pinworms.
The study served as a proof of concept that many of these diseases can be detected using this particular technology—even in very old feces. So the team had a list of 30 known gut microbes and pathogens they were looking for. Future research might search the dung heaps for lesser-known ones, or perhaps even new ones.
“Working with these ancient samples was like opening a biological time capsule,” Drew Capone, an assistant professor at the Indiana University School of Public Health, said in his report. statement. “Each reveals insights into human health and daily life more than a thousand years ago.”
Who knows what clues might emerge next, buried in ancient poop.
Main image: BRO.vector / Shutterstock.
