How Caffeine Became the World’s Favorite Drug

Whether in the form of tea, coffee, or a potent energy drink, there’s no denying the near-universal appeal of caffeine. This tiny molecule has been consumed for centuries in beverages and foods that offer a quick jolt of energy needed to make it through the day. And even though it’s not commonly thought of as a drug, or a substance that alters consciousness, it certainly is — and humans consume a whole lot of it.

But how did we all end up hooked on caffeine? Author Michael Pollan, whose 2021 book This Is Your Mind on Plants explores how people have used mind-altering flora like mescaline to change the way they see the world, has a few theories. Pollan sat down with Gastropod co-hosts Cynthia Graber and Nicola Twilley to talk about how caffeine evolved from its earliest uses as a natural insecticide into a morning essential for millions of people across the globe, transforming civilization as we know it along the way.

The conversation begins when Pollan describes what it was like for him to give up caffeine for a month as he researched his book, and the effects he saw from missing out on his daily cup of joe. Check out an excerpt from their conversation below.

Gastropod: Where can you find caffeine molecules in the wild?

Michael Pollan: It’s produced by several plants, most notably the coffee plant, the tea plant. Members of the citrus family produce caffeine also — that’s a curious case — and the kola plant produces it. It was hit upon by plants during their evolution as an insecticide, and also as a chemical that discourages other plants from germinating near you. Plants are very protective of their territory — at least some of them are — and if they drop leaves of a caffeine-producing plant, it’s very hard for other plants to germinate in their presence. But the main purpose [of caffeine] in the life of a plant is to poison insect predators, which it seems to do pretty well.

So when did humans start enjoying this insecticide and in what form?

What’s really interesting about caffeine, at least if you look at it from the point of view of people who live in the West, is that compared to other psychoactive plants that we’ve been involved with for thousands of years — peyote is 6,000 years, alcohol probably goes back even further — caffeine came to human attention fairly late; in the case of coffee, not until the 600s or so. It doesn’t come to the West until the 17th century. Before that, it was known to people in East Africa, in Ethiopia, and the Arabian Peninsula, and it was commonly drunk in the Arab world long before it arrived in Europe.

That’s why it’s a really interesting case study, because we can really look at civilization before and after caffeine. And its effect on Western civilization is profound: It ushers in what amounts to a new form of consciousness, a new way of perceiving the world that was incredibly helpful to things like the scientific revolution and the capitalist revolution. Because it cleared the Western mind, which had been badly clouded by alcohol.

We have very little sense of how drunk people were much of the time, before the advent of caffeine in Europe. Alcohol was something that people drank morning, noon, and night because alcohol was safer than water — you got diseases from water, but the fermentation process and the alcohol itself sanitized the water. So when you read accounts, people were kind of slightly addled all the time.

When caffeine comes in, it doesn’t obviously eliminate the use of alcohol, but it does reduce it. And a lot of people observed this in the 17th century — that, as a result, they’re clear, more focused, able to do things they couldn’t do before. This has a profound effect.

To go back in time a little bit, why were people on the Arabian peninsula consuming it? What did it do for them?

One of the first uses of coffee and tea, interestingly enough, is in the religious context. Sufi monks would use coffee to help them stay awake during long nights of prayer or meditation. And this was true, too, for Buddhists in China, who learned pretty quickly that tea was an aid to meditation. It helps with the focus that you want, and it also keeps you from falling asleep on the cushion. It really begins as a tool for religious observance.

And then it’s really interesting how it catches on in the Muslim world.

It was used in a way similar to how it came to be used in Europe, which was in coffeehouses. Very quickly after the introduction of coffee, this coffeehouse culture [emerges]: You go to these places, buy coffee, and you hang out for hours at a time, much as we do today at a Starbucks, and people talk business, or whatever their passion was.

What was interesting about a coffeehouse culture [in Europe] is that it very quickly subdivided into spheres of influence. So you’d have a coffeehouse for scientists that was associated with the Royal Society. There was another one where the literary types would hang out, and you could meet [poets John] Dryden or [Alexander] Pope. And then there were ones dedicated to business. There’s a coffeehouse that gradually turned into the London Stock Exchange, and another one that turned into Lloyd’s of London. There was another one that actually turned into the world’s first magazine, which was an attempt to duplicate the variety and currency of coffeehouse culture. So it was a really vibrant thing, and there was a point at which there was one coffeehouse for every 250 Londoners. That is astonishing proliferation.

These were interesting spaces. Women were not allowed. But the men that were allowed could be of any class. And it was the first public place where people of any class could sit in the same room. You didn’t have the divisions that you had in pubs that were [segregated] on the basis of class. So you had this very interesting mixing of people.

Coffee is getting big just as society is really shifting in Europe and work is changing in a fundamental way. So what was happening to how people lived that was so intimately suited to what caffeine could do?

What was happening was the Industrial Revolution, and coffee helped make that possible. Obviously, it wasn’t the only factor, but it’s hard to imagine an industrial revolution without caffeine. You needed something to keep people working hard, keep them focused, allow them to operate heavy machinery, and do dangerous work without, you know, being drunk.

The other thing it did, though, was open up night[time] to colonization, because, before we had caffeine, we were much more tightly yoked to the diurnal cycle. People tended to work from daybreak till sunset; the whole idea of a night shift or an overnight shift without caffeine is pretty hard to imagine. So caffeine frees us from the rhythms of nature to a remarkable extent, and allows us to push the workday deeper and deeper into the night.

One thing we thought was fascinating was that early scientists were trying to understand caffeine from a worker’s perspective. How were scientists trying to understand how caffeine and energy were related?

This comes a little bit later, around 1900, where you have this new academic discipline concerned with humans and work. Efficiency — kind of a mix of biology and social science — becomes a very important science. And one of the things they were trying to understand is, how was it that caffeine appeared to enhance people’s energy without giving them any calories. There was a pretty strict understanding that energy was a function of calories. But here was a noncaloric drink — leaving aside whether it was sweetened or not — that seemed to give people more energy. This seemed in violation of the laws of thermodynamics, and it looked very much like a free lunch in terms of giving people energy.

It was only later that we came to understand how you got energy from caffeine — that you were essentially borrowing it from the future. It wasn’t additional energy. The way caffeine works is that it, like a lot of drugs, closely resembles a neurotransmitter or neuromodulator. In this case, it’s adenosine, which is a very important neuromodulator that regulates the sleep cycle. Over the course of the day, adenosine levels build up in your body and create what is called sleep pressure. There are receptors dedicated to linking with adenosine. What caffeine does is hijack those receptors. It fits neatly into those receptors and then blocks the adenosine from doing its job.

But it’s not like adenosine goes away. The levels of adenosine in your bloodstream and in your brain continue to build. So when the caffeine is finally metabolized, the adenosine hits you like a ton of bricks because it’s been building up the whole time and you’re more tired than you would have been had you not had the caffeine.

Does caffeine have other effects on the body too?

One of the really interesting phenomenons that we’ve observed is better performance on test-taking, on memory, because of caffeine. But we’ve also observed all these health effects that drinks containing caffeine seem to be protective against: cardiovascular disease, Parkinson’s, against various kinds of cancer. And those may have nothing to do with the caffeine but may well have to do with what I thought was one of the most astonishing facts in learning about coffee, which is that coffee and tea are the leading source of antioxidants in the American diet.

That’s an astonishing fact. Antioxidants are critical to our health and they have a preventive effect with many cancers; the fact that we’re getting them all from coffee and tea, rather than plants and vegetables, is just a measure of how few vegetables we eat in this country. So the health effects may be explained by that, although nobody knows for sure. On balance, this is a wonderful drug.