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Dr. Luis Pezo-Lanfranco and his colleagues conducted stable isotope analysis to reconstruct the diets of 38 human individuals from the early Central Andean civilization of Vichama (1800 BCE–1300 CE).

The research is in the journal Frontiers in Environmental Archaeology.

Studies on the ancient Central Andean society have long debated over the balance between fishing and farming. Current evidence suggests that despite having one of the most productive marine ecosystems available and the extreme aridity of the surrounding landscape, farming was the prime mover of early Andean civilization.

Some of the earliest evidence of irrigation technology, linked to the cultivation of plants, emerged around 4000 BCE. By 3000 BCE, farming had become the most important economic activity in the region.

Additionally, the Peruvian coast experienced an exponential population growth between 2000 and 1 BCE, a process attributed to the interplay between environmental changes and agricultural regime expansion.

It is possible that the subsistence strategies employed may have been heavily influenced by these climate oscillations, changes in sea surface temperature, rainfall patterns, El Niño Southern Oscillation events, and other environmental phenomena.

Vichama, located ca. 130 km north of the modern city of Végueta, lies right on the margin of the lower Huaura Valley, only 1.5 km from the Pacific Ocean and around 6.5 km northwest of the river mouth.

Its variable surrounding ecosystems allowed the residents to exploit a variety of resources. For the study, 38 individuals coming from two phases of the Vichama occupation were analyzed. The first phase took place during the early Formative-1 (EF-1, 1800–1500 BCE), while the second occurred during the Late Intermediate period (LIP, 1000–1300 CE).

During the EF-1, Vichama experienced a flourishing of monumental architecture and became part of a complex emerging polity in the lower Huaura Valley.

Stable carbon and nitrogen isotope analysis of collagen and bioapatite extracted from human bones and teeth indicate that during the EF-1, individuals relied mainly on C3 plants such as beans, chilies, fruits, tubers, and roots, with marine resources making up only around <25% of their diet despite their proximity to the coast.

Interestingly, C4 plants (such as amaranth and maize) only constituted a marginal (<10%) part of the diet. Dr. Pezo-Lanfranco elaborates on this interesting observation.

"Theoretically, the valley is suitable for maize cultivation; however, local farmers have traditionally focused on other crops," explains Dr. Pezo-Lanfranco.

"The presence of maize has been confirmed at Huaca Prieta, in the Chicama Valley on the northern Peruvian coast, as early as 4500 BCE, and we know that maize was present during the Initial Formative period at sites such as Caral and other settlements in valleys of the North-Central coast (the region under study), but it was possibly reserved for special occasions or ritual contexts rather than regular subsistence.

"Moreover, this period experienced some degree of climatic instability. Given that maize requires a consistent water supply, it may have been considered a risky crop to cultivate in the Vichama area.

"It is plausible to imagine specialized maize-producing communities farther north, where valleys are broader and more suitable for intensive agriculture. In contrast, communities in this region may have preferred to rely on more resilient crops such as cucurbits and tubers."

Ca. 3,000 years later, during the LIP, marine productivity on the surrounding coast was high due to lower sea surface temperatures. However, while marine resources did constitute a greater part of the diet compared to the EF-1, C3 plants remained the primary source of food for Vichama residents.

The evidence seems to suggest that Vichama developed opportunistic and resilient subsistence strategies, intensifying either agricultural or marine exploitation based on prevailing climate conditions, yet relying predominantly on farming.

Future studies will focus on a variety of research directions, from pathological markers to micro-plant remains in dental calculus, Dr. Pezo-Lanfranco explains.

"Just right now, we are analyzing plant micro-remains in dental calculus, and stress markers and pathologies in the human remains. We are also investigating the climate conditions in Vichama using pollen and stable isotopes, in order to test dry conditions and water stress in local plants.

"We want to know why the center of regional power and ideology moves from Caral to Vichama. Possibly, a global phenomenon called '4.2 ka Event' was involved. In addition, we are investigating mobility patterns in the region.

"There is a lot of evidence of exotic artifacts from the Amazon (located around 300 km to the east through a natural geographic corridor), and we want to know if the people were moving in a west-east direction."

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