Bird guano created wealth for ancient Peruvian community

This is Islas Ballestas off the coast of the Chincha and Pisco valleys of Peru. It is an important location for several seabird species. The white substance on the cliffs is bird guano. There is less of it today because seabird populations are in decline. Image via Jo Osborn/ University of Sydney.

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• The Chincha kingdom in southern Peru, which existed 1,000 years ago, prospered because farmers used...