This ancient South American empire ran on bird feces

This ancient South American empire ran on bird feces

By Meghan Bartels Edited by Andrea Thompson

Thirteen miles off the coast of Peru are a trio of islands containing mountainous mounds of guano, known as “white gold.” This seabird feces, mixed with other wastes, is such a powerful nitrogen store that it inspired much of America’s imperial takeover in the late 1800s.

But guano was a known and valuable resource long before it arrived on the American scene. Now new research was published on 11 February one more It provides evidence that Peruvian civilization was flourishing before the rise of the Inca Empire in the early 1400s. applying guano obtained from those islands to one’s corn crop At least till 1250.

Sniffing out centuries-old traces of seabird feces might not be the most glamorous endeavor, but it’s the kind of clue archaeologists crave about long-lost people.

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“The origin of fertilizer is important because soil management allowing large-scale crop production would have been critical to allowing population growth and developing trade in crops,” says Emily Milton, an environmental archaeologist at the Smithsonian Institution’s National Museum of Natural History and co-author of the study.

And archaeologists have long known that the people living in Peru’s Chincha Valley were able to do exactly that, but with very few details about how, says archaeologist Jordan Dalton of the State University of New York at Oswego, who studies the region but was not involved in the new research. “We know they were a wealthy coastal kingdom – they interacted, traded and competed with their neighbors – but we don’t really understand the nature of those social relationships and what kinds of goods they were trading,” she says. “There’s a lot we need to fill in to really understand.”

In the new work, Milton and his colleagues examined the ratios of different isotopes of carbon, nitrogen and sulfur – forms of atoms that have different numbers of uncharged neutrons in their nuclei – in corn cobs that archaeologists discovered in the Chincha Valley. The general technique is an archaeological staple, but it has been applied more regularly to animal bones than plant material and rarely considers sulfur, Milton says.

The team’s interpretation of the analysis, combined with factors such as the presence of seabird iconography in the area, suggests that local societies were fertilizing exclusively with marine fertilizer by 1250.

This isn’t necessarily surprising, Dalton says, but it is valuable information about local agricultural technology. “Obviously there are different types of fertilizers that one can use, but guano is at the top because it is so rich in nitrogen,” she says. She is also looking forward to future work on how, for example, better access to guano might have made some communities more prosperous and powerful.

Milton says the work could also inform archaeologists working further away from the Chincha Valley. Scientists use isotopic analysis to understand the diets of ancient people and animals because focusing on either side of a surf-and-turf platter yields distinct chemical signatures. But fertilizing terrestrial crops with marine material can mess up this job.

“When people started adding seabird guano to crops, it created this kind of false marine signal in terrestrial food products,” says Milton. “You might find something that’s (in the camelid family), which should look terrestrial, but isotopically it might look like a shark or some kind of marine creature.”

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