The Neolithic Revolution marked a major turning point in history. During it, many communities transitioned from hunting and gathering to farming and herding, providing them with a more stable food source and allowing their populations to grow. Now, researchers suggest the transition may have happened much more rapidly than previously thought. Their evidence? Ancient residue from…pee.
Researchers recently studied urine salts to determine when humans began to domesticate animals in central Turkey, at the ancient settlement of Aşıklı Höyük. Previous archaeological excavation has shown that the settlement played an important role in the shift from nomadic lifestyles to permanent villages, and is also the site of the first known brain surgery.
The new research suggests the shift to animal domestication at Aşıklı Höyük occurred more rapidly than previously thought: between 8450 and 7450 B.C., it appears the people there became heavily dependent on domesticated sheep and goats for survival. The researchers’ findings bolster the theory that the agricultural revolution took place in multiple locations concurrently, rather than beginning in one location (the Fertile Crescent) and spreading out from there.
Archaeologists have studied ancient feces before, but the researchers think they may be the first to use ancient pee to track how humans and other animals lived thousands of years ago. In fact, the researchers who published their urine salt study in Science Advances only decided to use pee residue because they were having trouble reconstructing a timeline with feces and bone.
“We thought, well, humans and animals pee, and when they pee, they release a bunch of salt,” said lead author Jordan Abell, a graduate student at Columbia’s Lamont-Doherty Earth Observatory, in a university press release. “At a dry place like this, we didn't think salts would be washed away and redistributed.”
Though it’s not possible to distinguish human pee salts from those of other animals, the researchers used the salts to estimate population density. They found there was a turning point about 10,000 years ago when concentrations of urine salts in the archaeological layer became 1,000 times higher than those in previous layers. They estimate that between between 8450 and 7450 B.C., an average of 1,790 people and other animals lived and peed at Aşıklı Höyük every day.
This would’ve been too many people for the settlement buildings to support, which is why a lot of those urinators were probably sheep and goats. The sharp increase in pee salts around 10,000 years ago “may be new evidence for a more rapid transition” toward animal domestication, Abell said in the press release.
There are still a lot of questions remaining about where, when and how the Neolithic Revolution occurred. The pee salt study may be just a drop in the bucket, but it nevertheless helps us narrow the timeline for this region.