One of the most important transitions in human history was when we stopped hunting and gathering for food and instead settled down to become farmers. Now, to reconstruct the history of one particular archaeological site in Turkey, scientists have examined a pretty unexpected source – the salts left behind from human and animal pee.
The dig site of Aşıklı Höyük in Turkey has been studied for decades, and it’s clear that humans occupied the area more than 10,000 years ago, where they started experimenting with keeping animals like sheep and goats. But just how many people and animals occupied the site at different times has been trickier to track.
For the new study, researchers from the Universities of Columbia, Tübingen, Arizona and Istanbul realized that the more humans and animals there are on a site, the higher the concentration of salts in the ground. The reason? Everybody and everything pees.
The team began by collecting 113 samples from across Aşıklı Höyük, including trash piles, bricks, hearths and soil, from all different time periods. They examined the levels of sodium, nitrate and chlorine salts, which are all passed in urine.