Fossilized feces. Credit: North Dakota Geological Survey

Fossilized feces may sound gross, but its hidden lessons about microbes certainly don’t stink. A petrified piece of poop—called a “coprolite”—from the 14th century has unveiled the earliest evidence of antibiotic resistance genes in the human gut microbiome. The findings reveal how these genes were swapped among bacteria long before the era of antibiotics and modern medicine.

For more, check out the full story at Science Magazine.