When National Geographic caught up with Byrne at her home in London, she explained why humans aren’t the only primates that can curse and why, though women are swearing more today than before, it is still regarded by many as “unfeminine.”

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You write, “I’ve had a certain pride in my knack for colorful and well-timed swearing.” Tell us about your relationship to bad language, and in what sense it is good for us?

My first memory of being punished for swearing was calling my little brother a four-letter word, twat, which I thought was just an odd pronunciation of the word twit. I must have been about eight at the time; my brother was still pre-school. My mother froze, then belted me round the ear. That made me realize that some words had considerably more power than others, and that the mere shift in a vowel was enough to completely change the emotional impact of a word.

I’ve always had a curiosity about things I’ve been told I am not meant to be interested in, which is why I wound up in a fairly male-dominated field of artificial intelligence for my career. There’s a certain cussedness to my personality that means, as soon as someone says, “No, that’s not for you,” I absolutely have to know about it.

My relationship with swearing is definitely one example. I tend to use it as a way of marking myself out as being more like my male colleagues, like having a working knowledge of the offside rule in soccer. It’s a good way of making sure that I’m not seen as this weird, other person, based on my gender.



There’s great research coming out of Australia and New Zealand, which is perhaps not surprising, that says that jocular abuse, particularly swearing among friends, is a strong signal of the degree of trust that those friends share. When you look at the transcripts of these case studies of effective teams in sectors like manufacturing and IT, those that can joke with each other in ways that transgress polite speech, which includes a lot of swearing, tend to report that they trust each other more.

One of the reasons why there’s probably this strong correlation is that swearing has such an emotional impact. You’re demonstrating that you have a sophisticated theory of mind about the person that you’re talking to, and that you have worked out where the limit is between being shocking enough to make them giggle or notice you’ve used it but not so shocking that they’ll be mortally offended. That’s a hard target to hit right in the bullseye. Using swear words appropriate for that person shows how well you know them; and how well you understand their mental model.

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You were inspired to write this book by a study carried out by Dr. Richard Stephens. Tell us about the experiment, and why it was important in our understanding of swearing.

Richard Stephens works out of Keele University in the U.K. He’s a behavioral psychologist, who is interested in why we do things that we’ve been told are bad for us. For years, the medical profession has been saying that swearing is incredibly bad for you if you’re in pain. It’s what’s called a “catastrophizing response,” focusing on the negative thing that’s happened. His take on this was, if it’s so maladaptive, why do we keep doing it?

He initially had 67 volunteers, although he’s replicated this multiple times. He stuck their hands in ice water and randomized whether or not they were using a swear word or a neutral word and compared how long they could keep their hands in ice water. On average, when they were swearing they could keep their hands in the iced water for half as long again as when they were using a neutral word. This shows that the results are anything but maladaptive. Swearing really does allow you to withstand pain for longer.

Have men always sworn more than women? And, if so, why?

Definitely not! Historians of the English language describe how women were equally praised for their command of exceedingly expressive insults and swearing, right up to the point in 1673 when a book by Richard Allestree was published titled The Ladies Calling.” Allestree says that women who swear are acting in a way that is biologically incompatible with being a woman and, as a result, will begin to take on masculine characteristics, like growing facial hair or becoming infertile. He wrote, “There is no sound more odious to the ears of God than an oath in the mouth of a woman.”

Today we are horribly still in the same place on men versus women swearing. Although women are still considered to swear less than men, we know from studies that they don’t. They swear just as much as men. But attitudinal surveys show that both men and women tend to judge women’s swearing much more harshly. And that judgement can have serious implications. For example, when women with breast cancer or arthritis swear as a result of their condition, they’re much more likely to lose friends, particularly female friends. Whereas men who swear about conditions like testicular cancer tend to bond more closely with other men using the same vocabulary. The idea that swearing is a legitimate means of expressing a negative emotion is much more circumscribed for women.

I was fascinated to discover that it’s not just humans that swear—primates do it, too! Tell us about Project Washoe.

Out in the wild, chimps are inveterate users of their excrement to mark their territory or show their annoyance. So the first thing you do, if you want to teach a primate sign language, is potty train them. That means, just like human children at a similar age, that they end up with a taboo around excrement. In Project Washoe, the sign for “dirty” was bringing the knuckles up to the underside of the chin. And what happened spontaneously, without the scientists teaching them, was that the chimps started to use the sign for “dirty” in exactly the same way as we use our own excremental swear words.

Washoe was a female chimpanzee that was originally adopted by R. Allen Gardner and Beatrix T. Gardner in the 1960s. Later, she was taken on by a researcher in Washington State called Roger Fouts. Washoe was the matriarch to three younger chimps: Loulis, Tatu, and Dar. By the time they brought in Loulis, the youngest, the humans had stopped teaching them language, so they looked to see if the chimps would transmit language through the generations, which they did.

Not only that: as soon as they had internalized the toilet taboo, with the sign “dirty” as something shameful, they started using that sign as an admonition or to express anger, like a swear word. When Washoe and the other chimps were really angry, they would smack their knuckles on the underside of their chins, so you could hear this chimp-teeth-clacking sound.

Washoe and the other chimps would sign things like “Dirty Roger!” or “Dirty Monkey!” when they were angry. The humans hadn’t taught them this! What had happened is that they had internalized that taboo, they had a sign associated with that taboo, so all of a sudden that language was incredibly powerful and was being thrown about, just like real excrement is thrown about by wild chimpanzees.

You say, “swearing is a bellwether—a foul-beaked canary in the coalmine—that tells us what our social taboos are.” Unpack that idea for us, and how it has changed over the centuries.

The example that most people will be familiar with in English-speaking countries is blasphemy. There are still parts of the U.S. that are more observant of Christianity than others but, in general, the kinds of language that would have resulted in censorship in other eras is now freely used in print and TV media. However, the “n-word,” which was once used as the title of an Agatha Christie book and even in nursery rhymes, is now taboo because there is a greater awareness that it is a painful reminder of how African-Americans suffered because of racism over the centuries. In some communities, where that usage is reclaimed, they are saying that if I use it, it immunizes me against its negative effects.

That is an example of a word that has fallen out of general conversation and literature into the realm of the unsayable. It’s quite different from the copulatory or excretory swearing in that it is so divisive. The great thing about the copulatory and excretory swearing is that they are common to the entire human race.

In the digital world, you can swear at someone without actually being face to face. Is this changing the way we curse? And what will swearing in tomorrow’s world look like?

One of the difficulties with swearing in online discourse is that there is no face-to-face repercussion, so it allows people to lash out without seeing the person that they’re speaking to as fully human. But it’s not swearing that is the problem. It’s possible to say someone is worth less as a human being based on their race, gender or sexuality using the most civil of language. For example, when Donald Trump called Hillary Clinton “a nasty woman” rather than using the c-word, most of us were able to break the code. We knew what he meant but because he hadn’t sworn it was seen as acceptable discourse.

In the future, I think that swearing will inevitably be reinvented; we’ve seen it change so much over the years. As our taboos change, that core of language that has the ability to surprise, shock or stun the emotional side of the brain will change, too. But I can’t predict where those taboos will go.

This interview was edited for length and clarity.