What do you know about female sexuality? Whatever it is, chances are, says Wednesday Martin, it’s all wrong. “Most of what we’ve been taught by science about female sexuality is untrue,” she says. “Starting with two basic assertions: that men have a stronger libido than women, and that men struggle with monogamy more than women do.”

Martin pulls no punches. Her bestselling memoir Primates of Park Avenue cast her as an anthropologist observing the habits of her Upper East Side neighbours. She claimed among other shockers that privileged stay-at-home mothers were sometimes given a financial “wife bonus” based on their domestic and social performance. The book caused a furore, and is currently being developed as a TV series, with Martin as exec producer. Her new book, out this week, should be equally provocative. Entitled Untrue, it questions much that we thought we knew about women’s sexuality.

Her starting-point is that research into human sexuality has been, historically, overwhelmingly male-centric; “notable sexologists”, starting with Carl Friedrich Otto Westphal (1833-1890) are mostly male. You have to scroll through another 25, including Sigmund Freud and Alfred Kinsey, before you arrive at a female name: Mary Calderone (1904-1998), who championed sex education. And even in the subsequent 30 names there are only five women, including both Virginia Johnson (partner of the famous, and male, William Masters), and Shere Hite.

Women crave variety at least as much as men

All these men made certain assumptions about women’s sexuality. It’s no surprise that it was Hite who revolutionised thinking on female orgasm, arguing that it was not “dysfunctional” to fail to climax during intercourse. Crucial, too, says Martin, has been the work of Rosemary Basson, who realised that spontaneous desire, the kind sexologists had measured for years, was only one type of relevant desire, and that responsive or triggered sexual response is much more important for women. Measured on that scale it turns out that women are, in fact, every bit as sexually arousable as men.

New findings showed that women reported similar intensities of desire and arousal to men, and “a real shift in thinking” about females and monogamy. “We were taught that men were the ones who needed variety, but the exact opposite turns out to be the case,” says Martin. “Overfamiliarisation with a partner and desexualisation kills women’s libido. We used to think it’s only men who became sexually bored after marriage; turns out that’s not true. It’s when women get married that it’s detrimental to their libido.”

Facebook Twitter Pinterest ‘Men really caring about what women want sexually makes a huge difference’: Wednesday Martin. Photograph: Christopher Lane/The Observer

Martin isn’t here to talk about her own relationship, but for the record she’s 53, has been married for 18 years, still lives in New York, and has two sons aged 17 and 10 who are, predictably enough, “mortified” at what their mother writes about. She hopes her work will help validate the feelings of the next generation of young women: “It’s not about giving them permission to ‘cheat’, not even giving them permission to refuse monogamy, but I hope it does give them permission to feel normal if they don’t like monogamy,” she says. Because that’s the central fallacy: the belief that monogamy is harder for men than for women. In fact, argues Martin, the exact opposite is the case. “Women crave novelty and variety and adventure at least as much as men, and maybe more.” She talks me through what she says is the classic pathway for women when they marry or commit to one heterosexual partner long-term (the research has so far concentrated on heterosexual couples; more work is needed on gay women’s sex lives). “A couple live together, their libidos are matched, and they have a lot of sex. But after a year, two years, maybe three years, what tends to happen is that the woman’s desire drops more quickly than the man’s. At that point the woman thinks, ‘I don’t like sex any more.’ But what, in fact, is happening is that she is having a hard time with monogamy; because women get bored with one partner more quickly than men do.”

So women are socialised to believe that they’ve gone off sex, when in fact they’re craving variety. Instead of being the brake on passion, says Martin, the female half of the long-term partnership is the key to a more adventurous and exciting sex life. What it’s all about, she explains, is the existence of the only entirely pleasure-seeking organ in the human repertoire, the clitoris. For her portrait, she wears a necklace shaped like one. “Women evolved to seek out pleasure, women are multiply orgasmic, women’s biology sets them up to seek out pleasure,” says Martin. “The clitoris has a very important back story about female human sex which is that our sex evolved for the purpose of adventure.”

Another element in the mix, she says, was the finding that a third of women who are having an extramarital relationship say their marriage or long-term partnership is happy or very happy. “So we need to understand that women aren’t just seeking variety because they’re unhappy, they’re seeking it because they need variety and novelty,” she says.

There’s a generation in their 40s and 50s who missed the vibrator

What does all this mean, in a practical sense, for our sex lives? Martin doesn’t like the word “cheating” – she prefers to use the term “step out” – and that’s what some women decide to do. But it’s not the only solution. “There are many women who are suffering but don’t want to leave their relationship or to step out, and they’ve not yet discovered vibrators,” says Martin. “I can’t tell you how many women have told me they never had a vibrator – there’s a generation in their 40s and 50s who missed the vibrator revolution and never caught up. And there are all these new vibrators out there – and anything new you can introduce will make a big difference to your sex life.” Another way forward can be for a couple to open up their relationship in some way, and invite someone else in. And she has other ideas up her sleeve that seem a lot less risqué, like going on a zip wire, taking up dance lessons or going scuba diving together. Why does that help? “Research on the neurochemicals has found that our sexual desire is triggered when we do something new with a long-term partner. A thrilling activity is ideal: it can give you a wash of hormones that makes you feel new to each other again.”

Indeed, part of the narrative seems to be that men are too quick to settle for “the usual” (which makes sense now we know they’re not the ones who are bored); but opening up the conversation about what else they could try can relight the fuse. The trick here, counsels Martin, is for them to keep on and on asking. “Men really caring about what women want sexually makes a huge difference. You might need to have the conversation over and over, and women might keep saying they’re happy with things as they are – but keep asking, and eventually women will open up about their sexual fantasies. We find that their menus are more varied than men’s. Men are shocked, but also gratified and thrilled, when they find out how sexually exciting we can be when we get past the inhibitions that have been socialised into us.”

Paradoxically, there’s been a parallel shift in attitudes towards extramarital affairs and divorce alongside the growing studies into women’s sexuality. Martin quotes the US statistics: in 1976, fewer than half of well-educated Americans thought having an affair was always wrong; by 2013, that figure was 91%. “We’ve become a lot less tolerant of infidelity in recent years,” says Martin. “And meanwhile divorce has become much more common: a large number of people in the 1970s who thought affairs were OK, thought divorce was wrong.”

So at the precise moment science reveals women have the bigger “need” to be sexually adventurous, society clamps down on infidelity. And that, says Martin, is hugely significant. “The way we feel about women who refuse monogamy is an important metric for how we feel about equality.” She’s talking, she says, about women who openly refuse monogamy by being polyamorous. The overwhelming story we buy into, after all, is that men who “cheat” are just “men being men”; women who “step out” are far more likely to be criticised and shamed. Ultimately, though, they’re challenging something very deep in society’s expectations of them – and perhaps their stance is the most radical female stance of all.

Untrue by Wednesday Martin is published by Scribe at £14.99. Buy it for £12.89 at guardianbookshop.com