Most Delicious Poison: The Story of Nature's Toxins—From Spices to Vices

by Noah Whiteman

As sixteenth-century Swiss physician Paracelsus noted, “the dose makes the poison.”

The repeated origins of the same trait in different evolutionary lineages is called convergent evolution.

Pyrethrum powder remains one of the safest and most widely used natural pesticides in the world.

For example, a single ancient change in the DNA of insects makes their nerve cells a hundred times more sensitive to pyrethrins than ours. By contrast, cats and fish are sensitive to pyrethrins because they lack one of the liver enzymes we humans use to detoxify pyrethrins.

The lesson? Pick your poison—carefully. The origin story of each of these chemicals holds critical information on why the benefits may or may not outweigh the costs for human use. There is nothing inherently healthy about natural products.

Wormwood contains a plethora of toxins. One is a terpenoid called artemisinin, which was discovered by physician Tu Youyou in China in 1972 as a treatment for malaria. Her research landed her the Nobel Prize in Physiology or Medicine in 2015, and artemisinin remains the gold standard for an antimalarial drug.

Yarrow is known colloquially as bloodwort or nosebleed for its anticoagulant effects.

Salicylic acid, aspirin, and other nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen (and possibly the chamazulene from chamomile) suppress the production of hormones called prostaglandins. Prostaglandins play a key role in turning on the inflammatory response in our bodies, causing inflammation and pain.

Evolution applies the similarities and differences between plants (and other organisms, like fungi and bacteria) and animals to various organisms’ advantage. Plants have evolved to produce diverse chemicals that manipulate animal brains and brawn to their own ends, whether to keep us away or to draw us in. In turn, we have turned the tables ourselves and can tap into these chemicals as medicines and for other purposes.

The parsley family Apiaceae includes carrots, celery, cilantro, cumin, dill, fennel, parsley, and poison hemlock. The last-mentioned plant contains the alkaloid coniine, famous for allegedly killing Socrates. These plants, as well as those from the citrus, fig, and bean families, all make furanocoumarins, which are flavonoids.

Knowledge of how a substance can pivot from bad to good almost always flows from Indigenous and local knowledge holders and practices.

appeal-to-nature fallacy—that because something is natural, it is inherently good for us.

Blue and violet flowers tend to be bee-pollinated, while orange and red flowers—colors bees can’t see well—are often bird-pollinated because most birds can see red well. Orange and red are private color “channels” that plants evolved to advertise to their “subscribers” of a feathered variety.

traditional knowledge forms the basis for most of modern medicines derived from nature.

First, some hormones are produced by animals, humans, and plants. Second, plants and even some animals that have adapted to resist these hormones can overproduce the hormones to protect themselves from attack. And finally, both humans and other animals can turn the tables on plants and use pharmacologically active chemicals in the plants they eat to regulate important bodily processes like reproduction.

The initial recipe for this patent medicine included coca leaf extract and caffeine extracted from cola (or kola) tree nuts from Africa, hence the name Coca-Cola. The product went on sale on May 8, 1886, at the soda fountains of Jacob’s Pharmacy in Atlanta, where it was marketed to a white clientele as a temperance drink and “an esteemed brain tonic and intellectual beverage.”

There have been three distinct waves of the opioid overdose epidemic. The first began with the abuse of prescription semisynthetic opioid pills like hydrocodone and oxycodone. When those became less available, the second wave began as users turned to heroin. The third and current wave is fentanyl abuse, and it is unlikely to be the last.

One possible explanation for this is the expensive tissue hypothesis. It holds that the evolving human body traded disinvestment in digestive tissue for investment in brain tissue. In support of this hypothesis, primatologist Richard Wrangham and his collaborators proposed that our unique ability to cook using fire—essentially outsourcing some of the work of digestion to the cooking process—allowed the human brain to reach its current size. Wrangham’s “we are because we cook” theory proposes that cooking unlocked access to stores of carbohydrates needed to support what were the largest cerebral cortexes of any animal species: our own.

As the temperature of the geographic region goes up, so does the use of anise, basil, bay leaf, cardamom, celery, chilies, cinnamon, cloves, coriander, cumin, garlic, ginger, green pepper, lemongrass, mint, nutmeg, onions, oregano, saffron, and turmeric. As the temperature goes down, the use of dill and parsley goes up. The use of spices that are highly inhibitory to bacterial growth also increases with temperature, and dishes made in warmer countries are more inhibitory to bacteria than are those of cooler countries.

One of the simplest hypotheses is that we use spices because we like them—they taste good. Spices introduce new sensations that make us feel good or at least different. They enhance our experience because they are mildly psychoactive—they change our state of mind ever so slightly.

Infants and young children raised by abusive, neglectful, or stressed parents will tend to have brains more poorly wired to meet the challenges of being an adult. The fragility of young brains is one reason why humans are so susceptible to drug use disorders.

Paul Freedman, a historian of food, wrote that medieval Europeans were passionate about spices because of the “prestige and versatility of spices, their social and religious overtones, and their mysterious yet attractive origins. Versatility is especially significant because… spices were not used for just cooking. They were regarded as drugs and as disease preventatives in a society so often visited by ghastly epidemics… [T]hey were not only medicinal but luxurious and beautiful.”

To say that Run was traded for Manhattan because of a war over nutmeg would be hyperbolic but not entirely unfounded. Among other things, control over nutmeg, a substance that by the seventeenth century had come to be seen as a panacea, including a cure for the plague, was part of the equation.

Neither country signed the treaty and the Opium War continued, with nearly every battle won by the British. The conflict ended in August 1842, when the British threatened to sack Nanjing. The Treaty of Nanjing, signed by Queen Victoria and Emperor Daoguang, was about as lopsided as one could imagine. The Chinese would pay Britain fully ten times the cost of the dumped opium, Hong Kong would become permanent British territory, and several other cities, including Shanghai, would open up to trade. So began the Chinese “century of humiliation.”

From 1941 to 1945, the United States imported a staggering thirty-four million pounds of bark from cinchona trees and around forty-four thousand pounds of cinchona alkaloids from South America. The cache of imported bark grew to more than forty million pounds by 1947. The quinine obtained from the Cinchona Missions allowed the Allies to win the war in the Pacific theater. Perhaps more cryptically but arguably as important, the missions also fundamentally shifted Latin American loyalties away from Europe and toward the United States. This realignment of interests has had major economic, environmental, political, and social consequences.

The offerings made in exchange for these raw materials—from loans to scientific expertise—had strings attached that coincided with US style of agriculture: large-scale monocultures. In the end, advice from the United States superseded local knowledge. Unfortunately, the adopted US approach involved questionable agricultural and forestry practices like the introduction of unnecessary crops and the subjugation of Indigenous peoples. These practices continue to this day and have hastened the destruction of the world’s largest tropical rain forest, among other negative effects. And importantly, many of the remaining gray-barked Cinchona tree species of the Andean cloud forests are now threatened, owing to centuries of exploitation followed by deforestation and habitat degradation.

Both the mystique of the tropics and the value of its natural products drove the chain of events that led to our modern geopolitical order. So many aspects of our industrialized way of life—the tires on our cars, the drugs that save our lives, the spices we grind every day—depend on the products of ecological interactions between species in the tropics. Many of these natural products that we take for granted were first tapped by Indigenous peoples, largely in the tropics, from species living both in the primary rain forest and at its edges, in gardens. Yet the knowledge and sovereign lands of Indigenous peoples hold much more than just the future of the pharmacopoeia. Our past actions have finally caught up with us. The intertwined crises of our era—the biodiversity crisis and the climate crisis—now threaten the survival of the most diverse Indigenous cultures and biomes on the planet.