On my washing machine, there is a lock. To activate it, you must hold down the start button for a particular length of time at just the right intensity; too soft and nothing happens, too hard and the machine beeps angrily at you. Once you’ve mastered the technique, it’s easy; the lights switch on, things start moving and the cycle ultimately climaxes in a shuddering whirling crescendo of noise. Finally, an entangled heap of damp but refreshed clothes tumbles out at the other end. But for the uninitiated, it’s a perplexing mystery.

Consider now the female orgasm. JD Salinger once wrote that “a woman’s body is like a violin; it takes a terrific musician to play it right”. Pressed or caressed the right way, a woman can be transported to such ecstasy, that for a few seconds, the rest of the world ceases to exist. But get it wrong and pain, frustration, or dull nothingness can ensue. It’s a stark contrast to a man’s experience; so long as they can get an erection, a few minutes of vigorous stimulation generally results in ejaculation.

Why are orgasms so intensely pleasurable? How come women can experience multiple orgasms? And does the fabled G-spot even exist? These are some of the most enduring mysteries of medicine. “We are able to go to the moon, but we do not understand enough about our own bodies,” says Emmanuele Jannini at the University of Rome Tor Vergata – one of those who has spent his career trying to unravel it. Recent years have seen a flurry of studies by these real-life Masters of Sex, and they are finally getting some answers.

Brains on fire

Perhaps the scientists’ greatest skill is in persuading women to sweep aside their inhibitions, and masturbate – or even copulate – under the full glare of scientific research, including the uncomfortable environment of the fMRI scanner. One of the leaders of this research has been Barry Komisaruk at Rutgers University in New Jersey, who wanted to probe whether brain differences can explain why women and men experience sex so differently.