The droppings of Peruvian pelicans and Peruvian boobies have been prized for hundreds of years Biljana Aljinovic/Alamy Powerful fertiliser based on seabird droppings may have fuelled the rise of a Peruvian agricultural kingdom 900 years ago and helped drive its eventual takeover by the Incas. Chemical analyses of ancient maize cobs from southern Peru show unusually high nitrogen isotope levels – substantial signs that the plants were fertilised with a mix of seabird excrement, feathers and carcasses known as guano. The findings provide the strongest evidence yet that indigenous Chincha farmers, fishers and merchants harvested this nutrient-rich fertiliser from nearby islands to enhance inland crop fields – and strengthen their socioeconomic position, says Jacob Bongers at the University of Sydney. “Privileged access to a crucial resource is a pathway to power – which the Chincha Kingdom had in this case, and the Inca did not,” he says. “Social change may have arisen from a surprising source: bird poop. It’s a fascinating story.” Between AD 1000 and 1400, the wealthy and densely populated Chincha Kingdom controlled …