Bhumics 19: Coca as a Trace Substance
Trace Substances
When we think about the material foundations of culture and society, we tend to think of large masses of matter - cities, factories and farms, for example - whose accumulation and distribution structures human life. Food grains, iron, bronze and other metals, wood and concrete, increasingly carbon, these substances bear the weight, both figuratively and literally, of human society.
But they aren't the only substances that matter for several trace substances are woven into the fabric of human history the world over. Gemstones and precious metals are a good example - they are negligible in weight compared to iron and concrete, but you can’t deny the importance of gold and silver and diamonds to the course of history. Spices are another example: Pliny complained that the Roman Empire suffered a massive annual outflow of wealth due to its trade with India. He estimated that “there is no year in which India does not drain the Roman Empire of fifty million sesterces.” To this day you can find those sesterces littered across locations in South India. Pliny goes on to say:
Why do we like it so much? Some foods attract by sweetness, some by their appearance, but neither the pod nor the berry of pepper has anything to be said for it. We only want it for its bite – and we will go to India to get it. … Pepper and ginger both grow wild in their native countries and yet we value them in terms of gold and silver.
Pliny recorded cinnamon as being worth roughly 15 times the value of silver by weight. A kilogram of pepper cost 1-2 grams of silver at production, 10-14 in Alexandria, 14-18 in Venice, and 20-30 in consumer countries of Europe—demonstrating how tiny quantities generated enormous wealth through geographical arbitrage. Spices were so valuable they were used as offerings for the dead in ancient Egypt, with mummies found containing traces of Ceylon cinnamon, cassia, and juniper. In biblical times, Queen Sheba offered King Solomon "120 measures of gold, many spices, and precious stones," placing spices alongside the most precious materials known. The search for direct access to spice trade motivated the European Age of Exploration. Christopher Columbus and Vasco da Gama were sent specifically to find maritime routes to Asia's spice markets, ultimately leading to European colonization of the Americas and the establishment of global trade networks that persist today.
To use a chemical analogy, trace substances are catalysts of human reactions. Coca is no exception.
Throughout human history, certain materials have wielded influence far disproportionate to their physical presence. These "trace substances"—gold, silver, spices, silk, tea, opium, and coca—typically constitute less than 1% of global material flows yet have shaped empires, triggered wars, driven exploration, and fundamentally altered the course of civilization. Understanding coca's historical importance requires first recognizing its place within this extraordinary category of substances that transform societies through their scarcity, desirability, and concentrated value.
The Characteristics of Trace Substances
Trace substances drove the first waves of 'globalization' in the ancient world. Mummies were buried with Ceylon pepper. Lapis Lazuli from Afghanistan was the gemstone of choice in Babylon as well as Egypt. Makes sense: gemstones and spices and psychotropics are valuable, easy to transport and fetch a premium. Which is to say, TS's have:
High Value-to-Weight Ratios
Trace substances share several key characteristics that amplify their historical impact:
1. Extreme portability: Small quantities can be easily transported across vast distances
2. Concentrated value: Enormous wealth can be stored in minimal space
3. Universal demand: Desired across cultures despite geographical separation
4. Difficulty of substitution: No easy alternatives exist
5. Symbolic power: Often carry religious, cultural, or status significance beyond economic value
Network Effects and Global Integration
Trace substances create what economists call "network effects"—their value increases as more people use them, creating self-reinforcing cycles of demand and trade. The global silver trade, for instance, connected the Americas, Europe, and Asia in ways that would have been impossible with bulkier commodities.
Coca as a Trace Substance in the Incan Empire
Economic Infrastructure
Coca leaves functioned as both commodity and currency in the Inca Empire. Public officials and regional lords were paid for their services in precious metals, fine textiles, and baskets of coca leaves. The Sapa Inca himself rewarded loyalty with baskets of coca leaves, demonstrating its status alongside gold and silver. The exchange of coca leaves for other products such as meat, potatoes, beans, and vegetables was common practice, meaning coca played an important part in the Inca economy. Like spices in medieval Europe or silver in Ming China, coca became a medium of exchange that facilitated trade across the empire's vast territories.
Administrative and Communication Networks
The Inca postal system relied heavily on coca. The 'Chaskis'—young athletic couriers who traveled the empire on foot—made extensive use of coca leaves to perform their duties and cover great distances without fatigue. This relay service carried messages in the form of knotted cords called quipu at a rate of 150 miles per day across a road network of 14,000 miles.
This demonstrates coca's role in what we might call "imperial metabolism"—the systems that kept the Inca state functioning. Just as the British Empire later ran on tea and opium, the Inca Empire's administrative efficiency depended on coca's ability to sustain human performance across challenging terrain.
Military and Labor Systems
One of the most common uses of coca during Inca rule was in the context of mit'a labor—a labor tax required of all able-bodied men—and in military service. Coca was used as both medicine and performance enhancer, with properties including mild stimulation, anesthesia, hunger and thirst suppression, pain and fatigue alleviation, and altitude sickness relief. The Spanish colonizers quickly recognized this practical value. After conquest, enslaved Inca people were not capable of enduring the arduous labor the Spanish demanded without using coca, leading to its continued use in colonial mining operations despite initial Spanish attempts to suppress it.
Conclusion
Like pepper that drew Roman wealth to India or spices that launched the Age of Exploration, coca's minimal physical presence belied its massive cultural and economic impact. In the Inca Empire, these unassuming leaves became the invisible infrastructure of imperial power—fueling messengers across 14,000 miles of roads, sustaining laborers at crushing altitudes, facilitating trade networks, and binding communities through sacred ritual.
What makes trace substances uniquely powerful is their ability to transcend mere material utility and become embedded in the deepest structures of society. Coca wasn't simply a stimulant; it was currency, medicine, divine offering, and social bond simultaneously. This multi-dimensional integration explains why the criminalization of coca has been so devastating to Andean communities—it didn't just ban a plant, but severed connections to economic systems, spiritual practices, and cultural knowledge developed over millennia.
Understanding coca through the lens of trace substances also illuminates why contemporary efforts to "decouple" coca from cocaine are so significant. They represent attempts to restore a more accurate historical understanding: that concentrated value and cultural meaning, not bulk or mass, have been a driver of human civilization. The sacred leaf's journey from Inca treasure to global contraband reminds us that history's most consequential substances often come in the smallest packages.
