The Botany of Desire: A Plant's-Eye View of the World

by Michael Pollan

the chemical compound responsible for the psychoactive effects of marijuana: delta-9-tetrahydrocannabinol, or THC, a molecule with a structure unlike any found in nature before or since. For years Mechoulam had been intrigued by the ancient history of cannabis as a medicine (a panacea in many cultures until its prohibition in the 1930s, it has been used to treat pain, convulsions, nausea, glaucoma, neuralgia, asthma, cramps, migraine, insomnia, and depression)

The cannabinoid receptors Howlett found showed up in vast numbers all over the brain (as well as in the immune and reproductive systems), though they were clustered in regions responsible for the mental processes that marijuana is known to alter: the cerebral cortex (the locus of higher-order thought), the hippocampus (memory), the basal ganglia (movement), and the amygdala (emotions). Curiously, the one neurological address where cannabinoid receptors didn’t show up was in the brain stem, which regulates involuntary functions such as circulation and respiration. This might explain the remarkably low toxicity of cannabis and the fact that no one is known to have ever died from an overdose.

On the assumption that the human brain would not have evolved a special structure for the express purpose of getting itself high on marijuana, researchers hypothesized that the brain must manufacture its own THC-like chemical for some as-yet-unknown purpose. (The scientific paradigm at work here was the endorphin system, which is tripped by opiates from plants as well as endorphins produced in the brain.) In 1992, some thirty years after his discovery of THC, Raphael Mechoulam (working with a collaborator, William Devane) found it: the brain’s own endogenous cannabinoid. He named it “anandamide,” from the Sanskrit word for “inner bliss.”

cannabinoid receptors had been found in the uterus, of all places, and speculated that anandamide may not only dull the pain of childbirth but help women forget it later. (The sensation of pain is, curiously, one of the hardest to summon from memory.)

the human cannabinoid system evolved to help us endure (and selectively forget) the routine slings and arrows of life “so that we can get up in the morning and do it all over again.” It is the brain’s own drug for coping with the human condition.

Cannabis was one of the earliest plants to be domesticated (probably for fiber first, then later as a drug); it has been coevolving with humankind for more than ten thousand years, to the point where the aboriginal form of the plant may no longer exist. By now cannabis is as much the product of human desire as a Bourbon rose, and we have scant idea what the plant might have been like before it linked its destiny to our own.

The scientists I spoke to were unanimous in citing short-term memory loss as one of the key neurological effects of the cannabinoids. In their own way, so were the “poets” who tried to describe the experience of cannabis intoxication. All talk about the difficulty of reconstructing what happened mere seconds ago and what a Herculean challenge it becomes to follow the thread of a conversation (or a passage of prose) when one’s short-term memory isn’t operating normally. Yet the scientists said that the THC in cannabis is only mimicking the actions of the brain’s own cannabinoids. What a curious thing this is for a brain to do, to manufacture a chemical that interferes with its own ability to make memories—and not just memories of pain, either. So I e-mailed Raphael Mechoulam to ask him why he thought the brain might secrete a chemical that has such an undesirable effect. Don’t be so sure that forgetting is undesirable, he suggested. “Do you really want to remember all the faces you saw on the New York City subway this morning?” Mechoulam’s somewhat oblique comment helped me begin to appreciate that forgetting is vastly underrated as a mental operation—indeed, that it is a mental operation, rather than, as I’d always assumed, strictly the breakdown of one. Yes, forgetting can be a curse, especially as we age. But forgetting is also one of the more important things healthy brains do, almost as important as remembering. Think how quickly the sheer volume and multiplicity of se...

Our mental health depends on a mechanism for editing the moment-by-moment ocean of sensory data flowing into our consciousness down to a manageable trickle of the noticed and remembered. The cannabinoid network appears to be part of that mechanism, vigilantly sifting the vast chaff of sense impression from the kernels of perception we need to remember if we’re to get through the day and get done what needs to be done.* Much depends on forgetting.

The THC in marijuana and the brain’s endogenous cannabinoids work in much the same way, but THC is far stronger and more persistent than anandamide, which, like most neurotransmitters, is designed to break down very soon after its release. (Chocolate, of all things, seems to slow this process, which might account for its own subtle mood-altering properties.) What this suggests is that smoking marijuana may overstimulate the brain’s built-in forgetting faculty, exaggerating its normal operations.

All those who write about cannabis’s effect on consciousness speak of the changes in perception they experience, and specifically of an intensification of all the senses. Common foods taste better, familiar music is suddenly sublime, sexual touch revelatory. Scientists who’ve studied the phenomenon can find no quantifiable change in the visual, auditory, or tactile acuity of subjects high on marijuana, yet these people invariably report seeing, and hearing, and tasting things with a new keenness, as if with fresh eyes and ears and taste buds.

The cannabinoids are molecules with the power to make romantics and transcendentalists of us all. By disabling our moment-by-moment memory, which is ever pulling us off the astounding frontier of the present and throwing us back onto the mapped byways of the past, the cannabinoids open a space for something nearer to direct experience. By the grace of this forgetting, we temporarily shelve our inherited ways of looking and see things as if for the first time,

the story of the Assassins, which may or may not be apocryphal to begin with. The time is the eleventh century, when a vicious sect called the Assassins, under the absolute control of Hassan ibn al Sabbah (aka “the Old Man of the Mountain”) is terrorizing Persia, robbing and murdering with brutal abandon. Hassan’s marauders will do anything he tells them to, no questions asked; they have lost their fear of death. How does Hassan secure this perfect loyalty? By treating his men to a foretaste of the eternal paradise that will be theirs should they die in his service. Hassan would begin his initiation of new recruits by giving them so much hashish that they passed out. Hours later the men would awaken to find themselves in the midst of a most beautiful palace garden, laid with sumptuous delicacies and staffed with gorgeous maidens to gratify their every desire. Scattered through this paradise, lying on the ground in pools of blood, are severed heads—actually actors buried to their necks. The heads speak, telling the men of the afterlife and what they will have to do if they hope ever to return to this paradise.

One theory of the origins of agriculture holds that domesticated plants first emerged on dump heaps, where the discarded seeds of the wild plants that people gathered and ate—already unconsciously selected for sweetness or size or power—took root, flourished, and eventually hybridized. In time people gave the best of these hybrids a place in the garden, and there, together, the people and the plants embarked on a series of experiments in coevolution that would change them both forever.

defines the word biotechnology so broadly as to take in the brewing of beer, cheese making, and selective breeding: all are “technologies” that involve the manipulation of life-forms.

for reasons we don’t completely understand, distinct species do exist in nature, and they exhibit a certain genetic integrity—sex between them, when it does occur, doesn’t produce fertile offspring. Nature presumably has some reason for erecting these walls, even if they are permeable on occasion. Perhaps, as some biologists believe, the purpose of keeping species separate is to put barriers in the path of pathogens, to contain their damage so that a single germ can’t wipe out life on Earth at a stroke.

a diet of potatoes supplemented with cow’s milk was nutritionally complete. In addition to energy in the form of carbohydrates, potatoes supplied considerable amounts of protein and vitamins B and C (the spud would eventually put an end to scurvy in Europe); all that was missing was vitamin A, and that a bit of milk could make up. (So it turns out that mashed potatoes are not only the ultimate comfort food but all a body really needs.) And as easy as they were to grow, potatoes were even easier to prepare: dig, heat—by either boiling them in a pot or simply dropping them into a fire—and eat.

potatoes, which put an end to malnutrition and periodic famine in northern Europe and allowed the land to support a much larger population than it ever could have planted in grain. Since fewer hands were needed to farm it, the potato also allowed the countryside to feed northern Europe’s growing and industrializing cities. Europe’s center of political gravity had always been anchored firmly in the hot, sunny south, where wheat grew reliably; without the potato, the balance of European power might never have tilted north.

a new kind of environmental problem: “biological pollution,” which some environmentalists believe will be the unhappy legacy of agriculture’s shift from a chemical to a biological paradigm. (We’re already familiar with one form of biological pollution: invasive exotic species such as kudzu, zebra mussels, and Dutch elm disease.) Harmful as chemical pollution can be, it eventually disperses and fades, but biological pollution is self-replicating. Think of it as the difference between an oil spill and a disease. Once a transgene introduces a new weed or a resistant pest into the environment, it can’t very well be cleaned up: it will already have become part of nature.

Monoculture is the single most powerful simplification of modern agriculture, the key move in reconfiguring nature as a machine, yet nothing else in agriculture is so poorly fitted to the way nature seems to work. Very simply, a vast field of identical plants will always be exquisitely vulnerable to insects, weeds, and disease—to all the vicissitudes of nature. Monoculture is at the root of virtually every problem that bedevils the modern farmer, and from which virtually every agricultural product is designed to deliver him.

The potato famine was the worst catastrophe to befall Europe since the Black Death of 1348. Ireland’s population was literally decimated: one in every eight Irishmen—a million people—died of starvation in three years; thousands of others went blind or insane for lack of the vitamins potatoes had supplied. Because the poor laws made anyone who owned more than a quarter acre of land ineligible for aid, millions of Irish were forced to give up their farms in order to eat; uprooted and desperate, the ones with the energy and wherewithal emigrated to America. Within a decade, Ireland’s population was halved and the composition of America’s population permanently altered.