New research identifies llama dung as the key to the success of the Incan empire before the arrival of Europeans in South America.

At the height of their success as a civilization in the 14th and 15 centuries, the Incas ruled over about 775,000 square miles, most of which now makes up Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru.

A recent study led by Alex Chepstow-Lusty of the French Institute of Andean Studies in Lima, Peru, shows that llama poop began being used as fertilizer about 2700 years ago, and that marks the start of the mass growing of maize (corn).

This is significant, since before then, the main staple of their diet was quinoa. As the Inca population grew, quinoa was no longer capable of sustaining a large and advancing civilization. However, maize could, but due to the harsh and mostly inhospitable Andean highlands, growing maize would prove difficult until the introduction of llama poop.