Overview
- The peer-reviewed PLOS One paper published February 11 presents the strongest direct evidence yet that Chincha Valley farmers fertilized maize with seabird guano by at least 1250 CE.
- Stable carbon, nitrogen, and sulfur analyses of 35 archaeological maize cobs, anchored by isotopic baselines from 11 seabird bones, show elevated δ15N values consistent with guano manuring.
- Iconography depicting seabirds with fish and sprouting maize, together with colonial-era accounts of island guano collection, corroborates the biochemical findings.
- The guano was most likely sourced from the nearby Chincha Islands, and researchers argue the resulting maize surpluses supported merchants, population growth, and the kingdom’s emergence as a major coastal trading power.
- The study suggests access to marine fertilizer helped shape Chincha–Inca relations and expands the known geographic extent of pre-Hispanic guano use, while noting complex δ34S signals and calling for broader sampling to map scale and timing.