The study’s author, Alex Chepstow-Lusty of the French Institute of Andean Studies in Lima, counted pollen in layers of mud taken from Maracocha lake, near Ollantaytambo. His results indicated that 2,700 years ago, maize began to be grown in the area for the first time. Prior to this, the local people were mainly eating quinoa.

Maize had been growing in South America since it was introduced there from Mexico about 5,000 years ago. However, it was only grown at low altitudes until the locals added that secret ingredient. ‘Although a cereal such as maize is needed for civilisations to take off, and it provided many more calories than quinoa, or in fact potatoes, this widespread shift to agriculture and societal development was only possible with an extra ingredient – organic fertilisers on a vast scale,’ Chepstow-Lusty said.

The use of dung to fertilise maize crops was revealed when Chepstow-Lusty counted mites – which feed on broken down animal excrement – in the mud core. The highest abundances corresponded with the first appearance of maize pollen. ‘Llama herds used the pasture next to the lake, where they defecated communally,’ Chepstow-Lusty said. ‘This was food for the mites, but also provided fertiliser that was easily collectable.’

July 2011