Overview
- The peer-reviewed study, published February 11 in PLOS One, presents the strongest direct evidence to date of guano-fertilized agriculture in the Chincha Valley.
- Researchers analyzed 35 ancient maize cobs from 26 tombs across 14 cemeteries, recording δ15N values up to +27.4 that are attainable only with seabird guano.
- Baseline measurements from local seabirds, including cormorants, boobies and pelicans, align with the maize isotope ratios, confirming a marine nutrient source.
- The isotopic signal indicates intensive fertilization by at least around 1250 CE, coinciding with the Chincha Kingdom’s Late Intermediate Period expansion.
- The authors argue that guano-boosted yields supported economic growth and made the region attractive to the Inca, with laboratory work led in part by UC Merced also detecting similar enrichment in human hair from the sites.