Turns out, poo hasn’t changed that much over the centuries. In fact, long before antibiotics were used in medicine, feces from 14th century Belgium contained viruses with genes for antibiotic resistance.
A team of French investigators analyzed a fossilized sample of human excrement (their cocktail party small talk must be interesting: “So what do you do?” "Well...uh...") and they report, in the journal Applied and Environmental Microbiology, that while some of the specific phages have since evolved, the viral communities did much of the same work they do now.
Among those reconstructed functions: antibiotic resistance.
Both toxic compounds and antibiotics are common in nature, and, according to corresponding author Christelle Desnues, the resistance genes may simply be protecting the gut bacteria from them.
"Our evidence demonstrates that bacteriophages represent an ancient reservoir of resistance genes and that this dates at least as far back as the Middle Ages," Desnues said in a statement.
The ancient stool was discovered when an urban renewal project in Namur, Belgium, unearthed latrines dating back to the 1300s beneath the city square.
Over the last five years, considerable evidence has emerged that bacteria inhabiting the gut play an important role in maintaining human health, Desnues pointed out, and in turn, bacteriophage in the gut help keep bacterial populations in check.