In a new study, Danish researchers dug up old latrines and sequenced the DNA they found in the ancient poop. The results paint a picture of diets and parasites spanning times and places that range from an ancient fort Qala’at al-Bahrain, near the capital Bahrain in 500 B.C.E. to the river-ringed city of Zwolle in the Netherlands in 1850. The researchers published their results in the journal PLOS One.
The team collected samples of old latrines and soil deposits at eight different archeological sites. They screened the samples for the eggs of parasites, which can last for centuries, and analyzed the DNA in each sample to determine species. They also gleaned the DNA of plants and animals from the samples to determine what people ate.