A close examination of midden soil layers at the early Neolithic site of A??kl? Höyük in Turkey reveals that they are highly enriched in sodium, chlorine, and nitrate salts commonly found in human and goat and sheep urine, offering a distinct signal for following the management of those animals through the history of the site. The findings, along with an enriched nitrogen signal in the soil, suggest a new way for archaeologists to study the evolution of animal management at this critical point in human history, at similarly dry, thickly stratified sites that may not contain other domestication evidence such as animal bones or dung, or the presence of corrals or other animal enclosures. Jordan Abell and colleagues used several techniques to identify these soluble urine salts and to distinguish them from natural geological salt deposition at A??kl? Höyük. The researchers found a 5-10 times increase in these salts between about 10,400 BP to 10,000 BP, and a 10-1000 times increase between 10,400 and 9,700 BP, demonstrating increasing reliance upon and eventual domestication of sheep and goats over this time. Based on these salt concentrations, Abell et al. estimate that about 1,790 humans and animals lived and urinated on the site per day for roughly 1,000 years of occupation. High soluble nitrogen levels in the trash heaps of the site are similar to those seen in modern feedlots, the researchers note.
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Journal
Science Advances