The three staple crops that dominate modern diets—corn, rice, and wheat—are familiar to Americans. However, fourth place is occupied by an underdog: cassava.
Although almost unknown in temperate climates, cassava is an essential source of nutrition throughout the tropics. It was domesticated 10,000 years ago, on the southern margin of the Amazon basin in Brazil, and from there it spread throughout the region. With a shaggy stem a few feet tall, a handful of slender branches, and modest hand-shaped leaves, It doesn’t look like anything special.. Cassava’s humble appearance, however, hides an impressive combination of productivity, robustness and diversity.
Over millennia, indigenous people transformed it from a wild, weedy plant into a culture that stores prodigious amounts of starch in potato-like tubers, it thrives in the poor soils of the Amazon and is almost invulnerable to pests.
Cassava’s many active ingredients seem to make it the ideal crop. But there is a problem: Cassava is highly poisonous.
How can cassava be so toxic and still dominate diets in the Amazon? It all comes down to indigenous ingenuity. Over the past 10 years, my collaborator, César Peña, and I’ve been studying cassava gardens on the Amazon River and its numerous tributaries in Peru. We discovered dozens of cassava varieties, producers using sophisticated breeding strategies to manage their toxicity, and elaborate methods to process their dangerous but nutritious products.
Long history of plant domestication
One of the most formidable challenges faced by early humans was getting enough to eat. Our ancestors depended on hunting and gathering, catching fleeing prey and collecting edible plants at every opportunity. They were surprisingly good at it. So good that their populations soared, increasing outside the birthplace of humanity in Africa 60,000 years ago.
Still, there was room for improvement. Searching for food in the landscape burns calories, being the resource itself sought. This paradox forced a trade-off for hunter-gatherers: burn calories foraging for food or conserve calories by staying home. The tradeoff was nearly insurmountable, but humans found a way.
Just over 10,000 years ago, they overcame the obstacle with one of the most transformative innovations in history: domestication of plants and animals. People discovered that when plants and animals were domesticated, they no longer needed to be persecuted. And they could be bred selectively, producing larger fruits and seeds and more voluminous muscles to eat.
Cassava was the champion domesticated plant in neotropics. After its initial domestication, it spread throughout the region, reaching places as far north as Panama. within a few thousand years. Cassava cultivation has not completely eliminated people’s need to forage in the forest, but it has lightened the burden by providing an abundant and reliable food supply close to home.
Today, almost every rural family in the Amazon has a vegetable garden. Visit any home and you’ll find cassava roasted over a fire, toasted in a flatbread called casabe, fermented in beer called masato, and steamed in soups and stews. Before adopting cassava for these purposes, however, people had to figure out how to deal with its toxicity.
Processing a poisonous plant
One of cassava’s most important strengths, its resistance to pests, is provided by a powerful defense system. The system relies on two chemicals produced by the plant, linamarin and linamarase.
These defensive chemicals are found inside the cells of the leaves, stem and tubers of the cassava plant, where they generally lie idle. However, when cassava cells are damaged, by chewing or crushing, for example, linamarin and linamarase react, releasing a burst of harmful chemicals.
One of them is notorious: cyanide gas. The blast also contains other nasty substances, including compounds called nitriles and cyanohydrins. Large doses of them are lethal and chronic exposures permanently damage the nervous system. Together, these poisons deter herbivores so well that cassava is almost immune to pests.
No one knows how people first solved the problem, but ancient Amazonians developed a complex, multi-step detoxification process that transforms cassava from inedible to delicious.
It begins with grinding the starchy roots of cassava on chopping boards studded with fish teeth, stone chips or, more often today, a rough sheet of tin. Grinding mimics the chewing of pests, causing the release of cyanide and cyanohydrins from the root. But they float in the air, not in the lungs and stomach, as when they are eaten.
Next, the shredded cassava is placed in rinsing baskets, where it is rinsed, manually squeezed and drained repeatedly. The action of the water releases more cyanide, nitriles and cyanohydrins, and squeezing rinses them out.
Finally, the resulting pulp can be dried, which further detoxifies it, or cooked, which completes the process with heat. These steps are so effective that they are still used throughout the Amazon today, thousands of years since they were invented.
A Mighty Harvest Ready to Spread
Traditional Amazonian methods of grinding, rinsing, and cooking are a sophisticated and effective means of converting a poisonous plant into a meal. However, the Amazonians took their efforts even further, transforming it into a true domesticated culture. In addition to inventing new cassava processing methods, they began to monitor and selectively cultivate varieties with desirable characteristics, gradually producing a constellation of types used for different purposes.
On our travels, we found more than 70 different varieties of cassava that are highly diverse, physically and nutritionally. They include types that vary in toxicity, some of which require laborious crushing and rinsing and others that can be cooked as is, although none can be eaten raw. There are also types with different tuber sizes, growth rates, starch production and drought tolerance.
Their diversity is valued and they are often given fanciful names. Just as American supermarkets stock apples called Fuji, Golden Delicious and Granny Smith, Amazonian gardens stock yuccas called bufeo (dolphin), arpón (harpoon), motelo (turtle) and countless others. This creative cultivation consolidated cassava’s place in Amazonian cultures and diets, ensuring its manageability and usefulness, as well as the domestication of cassava. corn, rice It is wheat cemented their places in cultures elsewhere.
Although cassava has been present in South and Central America for millennia, its history is far from over. In the era of climate change and increasing efforts towards sustainability, cassava is emerging as a possible global crop. Its durability and resilience make it easy to grow in variable environments, even when soils are poor, and its natural resistance to pests reduces the need to protect it with industrial pesticides. Additionally, although traditional Amazonian methods for detoxifying cassava may be slow, they are easy to replicate and speed up with modern machines.
Furthermore, the preference of Amazonian producers to maintain different types of cassava makes the Amazon a natural repository of genetic diversity. In modern hands, they can be bred to produce new types, suiting purposes beyond those of the Amazon itself. These advantages led to the first export of cassava beyond South America in the 1500s, and its range quickly encompassed tropical Africa and Asia. Today, production in countries such as Nigeria and Thailand It far exceeds the production of the largest producer in South America, Brazil. These successes are increasing optimism that cassava can become a ecological source of nutrition for populations around the world.
While cassava isn’t yet a household name in the U.S., it’s well on its way. It has long gone unnoticed in the form of tapioca, a cassava starch used in pudding and boba tea. It’s also hitting snack aisle shelves in the form of cassava chips and the baking aisle using naturally gluten-free flour. Raw cassava is also an emerging presence, appearing under the names “cassava” and “cassava” in stores serving Latin American, African and Asian populations.
Track down a few and try them out. Supermarket cassava is perfectly safe and recipes abound. Cassava dumplings, French fries, cassava cakes …the possibilities of cassava are almost infinite.
This article was co-authored by Cesar Rubén Peña.
This article was republished from The conversation, an independent, nonprofit news organization that brings you trusted facts and analysis to help you understand our complex world. It was written by: Stephen Wooding, University of California, Merced
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Stephen Wooding receives funding from Projeto Amazonas, a non-profit organization that supports humanitarian and research projects in the Peruvian Amazon.
