The researcher found that maize pollen appears for the first time in the lake muds around 700 B.C., showing that the cereal could be cultivated at high altitudes of at least 3,350 meters (10,990 feet) above sea level..
Until then, Andean people were eating potatoes and quinoa, a grain-like plant similar to spinach which is very protein-rich.
According to Graham Thiele, an Andean agriculture specialist at the International Potato Center in Lima, maize indeed made a difference. More energy-dense than potato, it could be stored for much longer and was easier to transport.
"This really matters where there are no flat roads and wheeled vehicles and everything has to be carried on the back of a man or llama," Thiele told Discovery News.
"In addition, maize is more suitable for accumulation in elite controlled stores, and would have supported rent extraction by the emergent Wari and Inca elites. So maize trumps potato on transportability, storage and suitability for paying tribute," he said.
The lake sediment core also revealed that the highest abundance of oribatid mites, which eat animal dung, corresponded with the first appearance of maize.