SEX AND STYLE, commerce and culture, function and lust. No other garment is so typical of late modern civilisation and its fretful vanities as the bikini, 60 years old this summer. Four triangles of fabric, contrived both to conceal yet prioritise the erotic ground zeroes, contain much more than glands, mounds and folds. The bikini made sex stylish, predicting the dominant spirit of the age. Its significance goes beyond beach and pool: at once frivolous, but also meaningful, that itsy-bitsy, teeny-weeny, Lycra- enhanced, double-elasticised, two-piece swimsuit with high-cut leg is a perfect symbol of . . . us.

Two-piece swimsuits are not new. Roman mosaics in the Sicilian town of Piazza Armerina show women athletes with bare midriffs. Hollywood’s puritanical Hays Code of 1930 banned the exposure of the navel, but in 1935 an American designer called Claire McCardell showed an abbreviated maillot. In 1943 US fabric rationing encouraged economy in the matter of the conventional swimsuit’s ventral skirt panel. But none of these was a bikini because none was so intensely self-conscious, none so deliberately conceived both to shock and delight. To savour the astonishment of the bikini, consider an Edwardian beach scene. Modesty and chastity are the dominant influences: the contrast between Skegness in 1906 and beach volleyball in California 2006 is telling.

The bikini came from peculiarly modern circumstances. Europe was both depressed and elated at the end of the Second World War and fashion designers were looking for tonic remedies. One of them was Jacques Heim, the other Louis Reard, a car engineer. An engineering drawing exists dated “18 juillet 1946”. It shows a flat plan of a bikini bottom: rudimentary panels with string attachments. Heim’s and Reard’s shared quest was for thrilling diminution, a test for national morals.

Even in Paris the bikini was shocking. No conventional model was prepared to wear anything so explicit, so at Reard’s first commercial show at the Piscine Molitor in 1946 he had to hire a desensitised nude dancer from the Casino de Paris. Thus, one Micheline Barnardini, untroubled by modesty, launched the bikini. Heim had called his rival “L’Atome” because it was so small, inspiring Diana Vreeland, the doyenne of Vogue, to describe the bikini as “ the atom bomb of fashion”.

Of course, it is doubly poignant that this close-fitting symbol of decadent luxe, calme et volupte was inspired by nuclear physics. Bikini is one of the atolls in the Marshall Islands in the lonely part of the Pacific known as Micronesia. The Americans chose it as a site for atomic tests not because they were attracted by the charm of the inhabitants and their innocent ways, but because Bikini was comfortably remote from shipping lanes.

In March 1946 King Juda mournfully led away 167 Bikinians into an exile that ended only in 1968 when President Lyndon Johnson offered resettlement. But in 1975 radiation tests found continuing levels of plutonium-239 and 240 in the Bikini atmosphere and in March 2001, the Nuclear Claims Tribunal offered compensation of $563 million, which had risen to $725 million by the time the final settlement was made last year.

Meanwhile, with Marshall Islanders wretchedly replaced by cynical R&D for the Cold War, the bikini was becoming established as a symbol of the free modern spirit, of free-spending women and free love. Half a generation before the Pill, the first bikinis suggested that sex was not a matter of clinical family planning, but a recreational activity to be enjoyed at will. In a new world of expanded horizons, when paid holidays and foreign travel became an everyday reality in the West, the diminished swimsuit was an essential take-away. Evolution forced ever more audacious feats of function, fashion and daring. Reard said it was not a true bikini unless it could be passed through a wedding ring.

The bikini’s arrival exactly matches the acceptance of the sun tan and the origin of the “jet set”, a term coined by the journalist Igor Cassini (whose brother Oleg was Jackie Kennedy’s White House couturier). Mission Control for the jet set was the South of France, specifically St Tropez, Hedonism Central. Although in 1955 Diana Dors had worn a curious mink bikini at the Venice Film Festival, it was the following year when Brigitte Bardot sat in a wet bikini on the beach in front of Club 55 for Roger Vadim’s film Et Dieu . . . créa la femme, that bikini became irrevocably associated with style, sex and sun.

There were other landmarks in the chronology: Ursula Andress in the first Bond film of 1962, a Botticelli moment reprised by Halle Berry 40 years later. And in 1964 the inevitable occurred when designer Rudi Gernreich proposed the monokini — and topless applied to women as well as cabriolets. And the briefer the briefs became, folliculitis barbae presented itself as a significant problem: without bikinis, pubic hair would remain untamed, culture would not know the civilising effects of hot wax and “Brazilian” would refer only to a footballer.

What do the Micronesians make of all this, having banked three quarters of a billion in exchange for lives spent with geiger counters? Maybe they think, as I do, that bikinis are absurd: they make beautiful women more attractive and turn plain women repulsive. And as always when sex is involved, there is an elegiac quality. Bardot herself captured the bikini mood: “Helicopters filled the skies, swooping over super luxury yachts where pretty princesses shed their prejudices”.

Amazing how four tiny triangles carry so much raw meaning.

Times Recommends

• It’s the beginning of the affair
• Afghanistan: still a price worth paying
• Heroes of the downtrodden