We all swear, although some people swear they don’t. In one sense, swearing is benign, as in swearing on the Bible in court, or swearing by something you believe in, like a cure for warts. But we also swear in the more interesting and degener­ate sense of using taboo words, of the sort we are urged not to utter in front of the kids.

And kids, too, are often reprimanded or pun­ished for using taboo words. The wonder is how they learned them in the first place. Perhaps they are spread by older siblings or adult moles, or by parents who simply can’t refrain even when the kids are around. Children anyway seem to have an instinctive reaction to overly moralising parents or teachers, and irresistibly seize the opportunity to shock. Being told one must never say a particular word creates an irrepressible desire to say it, just as being told that one must not think of a polka-dotted elephant makes it very hard not to create precisely that image in the mind.

Surveys show that about two-thirds of swearing has to do with frustration, anger or surprise. As an aggressive weapon, swearing may serve as a sub­stitute for physical assault. Studies have demon­strated that it is more common in those who rank low in social standing, in extroverts and in those with high levels of hostility, and less common in people who are agreeable, conscientious, religious or sexually anxious. Swearing can also be simply a kind of slang, often no more offensive than other cult words, such as “awesome” or “cool”. It may also be a badge of allegiance, especially among groups of men.

Swearing seems to be deeply embedded in the brain. People who have lost the normal use of speech due to brain damage often retain the singu­lar ability to utter profanities, and understandably may do so profusely. This suggests that swearing can be automatic and ungoverned. Another exam­ple comes from Tourette’s syndrome, an inherited neurological disorder characterised by involuntary swearing and cursing (coprolalia), along with tics, head jerking, spitting and yelping. Victims of the disorder are embarrassed by their profanities, but have no control over them.

The earliest profanities are probably religious, prompted by strict teaching not to take the names of God or gods in vain. In an increasingly secu­lar society, especially in the West, these taboos have largely lost their power to offend. Oaths like “Jesus!”, “Christ!”, or “God in heaven!” are now almost empty of shock value. In earlier times, reli­gious profanities were often sanitised, as in “jeep­ers!”, “cripes!” or “gosh!”, but such terms have largely disappeared. In some cultures though, re­ligious terms have retained the power to shock. In French Quebec, the most effective profanities still relate to the church and its liturgy, as in expletives such as “tabarnak!” (tabernacle) or “calice!” (chal­ice). “Merde!” is relatively mild.

Nevertheless, religious doctrine may also under­lie the taboos against terms relating to defecation and sexual function, but these too have lost much of their impact. Expressions like “bugger!”, “shit!”, “piss off!”, “bollocks!” or “cock-up” punctuate nor­mal conversation without arousing much disapprov­al, except perhaps in some leafy avenues of genteel society. The F-word was once replaced by sanitised variants, such as “friggin’” or “feckin’”, but is now part of regular discourse and is widely heard on TV, often as a culinary accompaniment. The C-word is still largely taboo, perhaps due to a persisting sexual taboo mixed with the residues of old-time chival­ry—and maybe a pinch of feminism.

But change can be swift. In 1914, the phrase “Not bloody likely!” caused an uproar when ut­tered on an English stage, in 1956 the All Black Peter Jones shocked the nation by declaring him­self “absolutely buggered!” on public radio, and in 1972 Germaine Greer was fined for saying “bullshit” in a speech in the Auckland Town Hall. Domains of disapproval have now largely shifted from the religious and scatological to the political, probably because we are controlled by lawmak­ers rather than religious authorities. The strongest taboos are against racial terms. The N-word, for example, is not heard on TV, but may surface in racist insults hurled by street gangs. Other defama­tory terms for cultural and indigenous minorities have largely disappeared from everyday discourse, and retain a genuine power to offend.

Taboo words will persist, if only because taboos themselves reflect necessary controls over human behaviour. Unchecked, we are an unruly species. But taboo words are also valuable in providing outlets for frustration that fall short of physical vio­lence. A world without taboos, and taboo words, might be an altogether more dangerous place.