Early Holocene Coca Chewing in Northern Peru

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Introduction

Coca production and the mastication of its leaves have long been part of the indigenous Andean economy, providing nutritional, medicinal and digestive properties. The origin and use of the coca plant in South America have long been debated in anthropology, botany, medicine and Latin American politics. Although the history of coca chewing extends back into pre-Columbian times (Plowman 1979; Plowman & Hensold 2004), several issues are poorly understood. They are the dates by which people began to routinely exploit this plant, the specific ancient technologies employed to extract its alkaloid stimulants and nutritional qualities (Rury & Plowman 1983; Pacini & Franquemont 1985), and the wider social and economic impact of the crop on early community development.

This report is of a study of the macrobotanical remains of archaeological coca leaves (Erythroxylum novagranatense var. truxillense) preserved in the buried house floors of early Holocene foragers and cultivators that provides direct evidence of the consumption of this plant in tropical dry and humid forests on the lower slopes of the Andes in north-western Peru. Two AMS radiocarbon dates on leaves indicate that coca chewing began by at least 8000 cal BP, the earliest use known to date. Our data also reveal evidence for baking calcium-bearing rocks to produce lime to extract alkaloids from the leaves. The production of lime was segregated spatially from individual domestic households located across the valley, suggesting it was a community activity.

Use of coca

The genus Erythroxylum includes at least 230 species of coca that are distributed from Mexico and the Bahamas to north-west Argentina (Plowman 1979; Plowman & Hensold 2004). Only the cultivated species contains enough alkaloid to be worthy of chewing as a stimulant (Rury & Plowman 1983; Pacini & Franquemont 1985). Today, the species E. novogranatense var. truxillense is cultivated in semi-tropical to tropical areas on the lower western slopes of the Ecuadorian and Peruvian Andes. This small leaf variety was called tupa coca by the Inca, and was considered royal coca because it had a high content of wintergreen oil and other compounds (Rostworowski 1988). This variety is drought resistant and adapted to arid conditions, but still depends on irrigation on the western slopes of the Peruvian Andes. Its principal habitat is the tropical chaupiyiunga zone located at 500-1500m in elevation, where the average temperature ranges from 18-25[degrees]C (Plowman 1979; Ugent & Ochoa 2006). There are no known wild progenitors of E. coca novagranatense on the western slopes of the Andes, suggesting that it was developed from E. coca coca somewhere on the eastern slopes (Plowman 1983), or possibly in the upper Maranon Valley, and transported to the Nanchoc Valley. E. coca novagranatense is a variety selected through cultivation probably for its aridity tolerance and its aromatic oils which provide a preferred taste.

Prior to our radiocarbon dates on coca leaves, it was thought that the late Preceramic inhabitants of the Ecuadorian and Peruvian coast were consuming coca by at least 5000 cal BP (Engel 1963; Klepinger & Kuhn 1973; Lathrap et al. 1976; Cohen 1978). A calcite (or lime) alkali is required to release coca alkaloids. Powdered lime has been found in contexts dating to c. 5000 cal BP and presumed to be associated with coca chewing. The importance of coca was emphasised and exploited during the Inca and later Spanish colonial periods (Cieza de Leon 1973; Chavez Velasquez 1977). It was used as a stimulant to reduce fatigue, hunger, high-altitude hypoxia and thirst and as a medicine and digestive. The alkaloids in coca improve the metabolism of starches, thus providing a surge in energy and a reduction of fatigue. But coca was not just for chewing. It was also a symbol of social status and ethnic identity and an element of oracles and rituals (Plowman 1983). …