The Divine Leaf: Coca, Hayo, Ipadú, and Tupa

What we call coca is actually four distinct but closely related crops from separate regions of tropical South America. The leaves are consumed by millions of South Americans for ceremonial purposes, as topical and internal medicine, and as a masticatory for a mild stimulant effect. The coca crops produce a variety of chemical compounds for their defense against insect herbivores, including nicotine and, most infamously, cocaine. The mild stimulant and medicinal effects of chewing the leaf are not equatable to a cocaine high; in fact some consumers in Bolivia actually prefer sweeter leaves with lower cocaine content (Sauvain et al. 1997).

The cocas are sacred plants for millions of indigenous South Americans – as a workaday stimulant, an effective natural medicine, and a potent symbol of indigenous hegemony, community integrity, and interconnection of man and Earth – representing a profound relationship that I believe the majority of Westerners, including myself, cannot fully comprehend.

Following traditions that have flourished for millennia in the Andes and Amazon regions of South America, coca leaves are easily picked from shrubs that are resistant to pests and grow in a variety of habitats, the leaves are toasted and stored. "Chewing" coca leaves is a simple process where 5-20 leaves are arranged, placed in the mouth, and gently macerated before being stored in the cheek. After a few minutes, an experienced consumer will feel the effects as a subtle, clear, focused stimulation similar to a cup of coffee or strong tea, but without the jitters and trips to the bathroom that come with a dose of caffeine.

Botanically, there are four taxonomic varieties of coca farmed today in four different regions of South America for traditional use of the leaf. Ipadú coca leaves (Erythroxylum coca variety ipadu) are pulverized and consumed as a powder along many tributaries of the Amazon river, with the highest density in the Colombian Amazon region. Second, Coca (E. coca variety coca) is the variety grown in the Andean/Amazonian foothills of Bolivia, Peru, and Ecuador. The last two varieties, Hayo (E. novogranatense variety novogranatense) and Tupa (E. novogranatense variety truxillense) represent a distinct lineage from Coca and Ipadú that was domesticated independently from coca and ipadú. Hayo is the leaf grown in Colombia and Venezuela and Tupa is grown today in the very dry valleys of northwestern Peru and a small population persists on the Colombia/Ecuador border. Tupa is the source of the the flavoring agent used by Coca-Cola®, methyl salicylate aka wintergreen oil. 

What truly amazes me is that these different crops -- Coca, Ipadú, Hayo, and Tupa -- were created by three (possibly two -- I'm working on it) independent domestication events from the ancestral wild species, Erythroxylum gracilipes. This means that within the past 10,000 years, at least three different cultures in at least three different places and times brought a wild Erythroxylum gracilipes plant into cultivation and ultimately transformed it through domestication to create a new crop plant we now know generally as coca. 

Thus, at least three different Holocene peoples transformed the same natural resource to generate a useful, workaday stimulant. 

Over the past 50 years, breeding crosses of all four varieties for illicit cocaine production has created a dozens of new hybrid coca strains (see Galindo Bonilla & Fernandez-Alonso, 2010, below). 

The broad goal of my research is to define the identity of coca by understanding its origins of domestication, diversification into modern lineages, and genetic and chemical diversity. With colleagues, especially those at Proyecto Khoka (www.khoka.org). I also integrate data from anthropological and archaeological sources to reciprocally elucidate the history of civilization and crop domestication in South America.

Together with many great colleagues, our genetic research shows that humans created coca by domesticating the widespread wild relative E. gracilipes. Surprisingly, this happened two or three separate times in separate places in tropical South America. One domestication event in the northwest (Colombia, Ecuador, northern Peru, or Venezuela) created the ancestor of Colombian and Trujillo cocas. Apart from this, it is still uncertain whether Huánuco/Bolivian coca and Amazonian coca were the product of a single domestication or domesticated independently of each other (see "The Origins of Coca" paper below). This research has laid a new framework to understand the diversity of the coca crop, but many questions and refined hypotheses will develop as we continue research. Building on this initial phase, we have two sparkly new genome assemblies (as of Jan. 2022) and many more interesting samples to further define the identity of coca and its history and relationship with humans.

One of the most remarkable pieces of evidence from archaeological research is the discovery of Trujillo coca leaves from northern Peru that are 8,000 years old. This site, excavated and analyzed by Tom Dillehay and colleagues, was a place of production of the llipta (yeep-tah) ash, which is usually added to coca leaves to potentiate their effect. A Llipta sample recovered from this site is 9,000 years old. making coca one of the oldest crops in the Americas.