In 1532, the Spanish conquistador Francisco Pizarro and his European contingent apprehended the Inca sovereign, Atahualpa, within the Peruvian city of Cajamarca. This pivotal event precipitated the eventual subjugation of the Inca Empire.
Prior to this momentous confrontation, Pedro Pizarro, an associate of Francisco, made a noteworthy observation: apart from the Inca himself, the Lord of Chincha was the sole individual present in Cajamarca to be transported on a carrying platform, commonly referred to as a litter.
The question arises: what elevated the Lord of Chincha to such a prominent standing within Inca societal hierarchies? Our recent investigation, disseminated through the academic journal PLOS One, uncovers compelling evidence suggesting a surprising genesis of influence and authority: avian excrement.
A potent and precious resource
Chincha, situated in southern Peru, is one of many river valleys gracing the desert coastline, sustained by water originating from the Andean highlands, a crucial element for agrarian endeavors. Approximately 25 kilometres offshore lie the Chincha Islands, harbouring the most substantial guano deposits in the Pacific Ocean.
Seabird guano, essentially their droppings, functions as an exceptionally effective organic fertiliser. When contrasted with terrestrial animal manures, such as bovine dung, guano boasts a significantly higher concentration of nitrogen and phosphorus, indispensable nutrients for plant vitality.
Along the Peruvian coast, the Humboldt/Peru ocean current fosters abundant marine life. These rich fisheries, in turn, sustain vast congregations of seabirds that frequent the rocky insular formations offshore.
Owing to the arid, virtually rainless climate prevalent in the region, the accumulated seabird guano remains intact, piling up to significant depths. This distinctive environmental confluence renders Peruvian guano particularly esteemed.
Our investigation integrates iconographic analysis, historical narratives, and the stable isotope examination of archaeological maize (Zea mays) specimens. This multidisciplinary approach demonstrates that Indigenous communities within the Chincha Valley employed seabird guano for agricultural fertilization and yield enhancement for no fewer than 800 years.
We posit that guano was instrumental in the ascent of the Chincha Kingdom and its eventual integration into the Inca polity.
Lords of the desert coast
The Chincha Kingdom, flourishing between 1000 and 1400 CE, represented a large-scale societal construct estimated to encompass 100,000 individuals. It was organised into specialised occupational groups, including fisherfolk, cultivators, and traders. This civilisation held dominion over the Chincha Valley until its incorporation into the Inca Empire during the 15th century.
Given the proximity of the Chincha Islands, known for their historically significant guano deposits, the Peruvian historian Marco Curatola proposed in 1997 that seabird guano constituted a primary source of Chincha’s affluence. Our research lends substantial corroboration to this hypothesis.
A biochemical test
Biochemical analysis offers a validated methodology for ascertaining the historical application of fertilisers. An experimental investigation conducted in 2012 revealed that crops cultivated with camelid (alpaca and llama) and seabird dung exhibited elevated nitrogen isotope concentrations compared to unfertilised crops.
We subjected 35 maize samples, exhumed from graves within the Chincha Valley and documented in a prior study concerning funerary customs, to analysis.
The majority of these samples displayed higher nitrogen isotope values than anticipated for unfertilised maize, inferring the employment of some form of fertilisation. Approximately half of the samples registered exceptionally elevated readings. These findings are, to date, exclusively consistent with the utilisation of seabird guano.
This chemical attribution confirms the application of guano to pre-Hispanic agricultural produce.
Imagery and written sources
Guano, along with the avian species responsible for its production, evidently held broader cultural significance for the Chincha populace.
Our assessment of archaeological artifacts suggests that the Chincha people possessed a profound comprehension of the interconnectedness between terrestrial, marine, and celestial realms. Their engagement with guano and their relationship with the offshore islands transcended mere utilitarian considerations, becoming deeply ingrained within their worldview.
This profound reverence is palpably evident in Chincha’s material culture. Throughout their textiles, pottery, architectural embellishments, and metalwork, recurring motifs of seabirds, piscine life, oceanic undulations, and burgeoning maize stalks are consistently observed.
These visual representations underscore the Chincha’s acute awareness of the complete ecological cycle: seabirds subsisted on marine fauna, yielding guano; guano nourished the maize crops; and the maize, in turn, sustained the population.
This intricate relationship may even find expression in contemporary local Peruvian toponyms. The moniker “Pisco” is etymologically linked to a Quechua term for “bird,” while “Lunahuaná” potentially denotes “people of the guano.”
Poop power
As a highly effective and valuable fertilising agent, guano empowered Chincha communities to augment their harvests and broaden their trade conduits, thereby facilitating the economic expansion of the Chincha Kingdom.
We propose that fisherfolk undertook voyages to the Chincha Islands to procure guano, which they subsequently supplied to agriculturalists as well as maritime merchants for coastal and highland commerce.
Chincha’s enhanced agricultural output and burgeoning commercial influence would have amplified its strategic significance within the Inca Empire. Circa 1400 CE, the Inca integrated the Chincha into their dominion through a predominantly “peaceful” capitulation, forging one of the era’s few meticulously planned alliances.
While the precise nature of the accord between Chincha and the Inca remains a subject of scholarly debate, we contend that seabird guano played a role in these deliberations. The Inca state exhibited a keen interest in maize and lacked direct access to marine-derived fertilisers. This strategic imperative might explain the considerable deference afforded to the Lord of Chincha, evidenced by his elevated transport on a litter, as documented by Pedro Pizarro.
The Inca valued this fertilising substance to such an extent that they instituted measures to restrict access to the guano islands during avian breeding periods and imposed the death penalty for the unlawful killing of guano birds, whether on or off their island habitats.
Our study extends the recognised geographical prevalence of guano fertilisation within the pre-Inca world and strongly supports scholarly assertions regarding its pivotal role in the ascendancy of the Chincha Kingdom. Nevertheless, considerable scope remains for elucidating the full extent of this practice and its temporal origins.
