Secrets of the phwoah factor: what makes a woman sexy? Licence my roving hands, and let them go, Before, behind, between, above, below. So wrote the future Dean of St Paul's in his Elegy XIX, also known as "To His Mistress Going to Bed." Donne compares the female body to an unknown territory waiting to be explored. The question of what our roving hand, and equally roving eye, prefers is a matter of taste and taboo. These change with history: attractive parts of the body keep, as it were, moving. If Victorian painting is anything to go by, the ear disappeared in the middle of the 19th century when hair made it quite invisible. Meanwhile, Japanese artists of ukiyo-e pleased their clients by offering a faceless woman's nape of the neck as an eroticised zone. Although Flanagan-style breast worship goes back to the pre-historic cult of the Syrian goddess Astarte, the modern discovery of the body and the (shifting) veneration of its different components is a more recent part of the story of consumerism. Certainly, waists, breasts, eyes, bottoms and hair have always been revered, but the emphasis we give them changes. And, while those hormones have a belligerently non-negotiable role in our motivation, and while biology establishes the general arrangement of the woman's body, it is culture that directs our preferences. Culture literally shapes our desire. As Madge Garland explained in her 1957 book The Changing Face of Beauty: "Art is always in advance of nature, and again and again an artist conceived a new type of woman which a later generation copies." And in our era, those artists are not in studios, but in factories and advertising agencies. Take Helen Flanagan's bra, for example. Thorstein Veblen, the great social critic who wrote The Theory of the Leisure Class, regarded the bra - which sculpts and projects - as a form of mutilation. It was originally more of a prosthetic, a functional support, than an artistic device. Its commercialisation we owe to Boston socialite Mary Phelps Jacob in a patent of 1914. Jacob sold the design to the Warner Brothers Corset Company for $1,500. In 1935, Warner established "cup" sizes, thus a hierarchy of preference was established. Although it might surprise the knuckle-draggers at FHM, the determinators of female sexiness have often been women. It was, for example, a Mad Woman who presented blondeness as sexually desirable. This was Shirley Polykoff, a vice-president of the advertising agency Foote, Cone & Belding. She was a dark, Jewish woman who advocated the pleasures of being fair: "If I have one life, let me live it as a blonde," she flagrantly wrote. Polykoff's Clairol ads promoted an outrageous sexism that makes the Jon Hamm character in Mad Men appear a celibate recluse. Her "Does she or doesn't she?" ad about hair dye was banned by Life magazine for being too suggestive. Unabashed, Polykoff next wrote: "The girl with the beautiful mouth has it made." In 1955, "mouth" was almost an obscenity. FHM's Sexiest Women has its origins in the notorious beauty parades, the best example of which was the original Miss World competition that started in 1951. But there have been more brainy precedents. Charles Darwin's cousin was Francis Galton, the psychometrist who coined the word "eugenics" and created the Beauty Map of the British Isles. In this, he assessed and tabulated the looks of 10,000 women, judging them "attractive, indifferent, or repellent." He noted: "I found London to rank highest in beauty; Aberdeen lowest." Interestingly, Galton's categories are similar to the spectrum of sexual desire described by Stephen B Levine, author of a 1975 paper on the subject of female attractiveness. The path of lust, Levine says, is aversion, disinclination, indifference, interest, need, passion. Of course, this path is circular since aversion and passion are really rather close. Certainly, sexiness is not simplistic. But none of this takes full account of the vagaries of desire, and the unexpected places where its pitiless gaze lands. I once organised a dinner in Downing Street which Mrs Thatcher hosted. The next morning, one of the guests called and said: "My God! She's amazingly sexy. Did you see her hands? Stephen Bayley is a design critic and author of 'Woman as Design