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Which Sex Wins Is a Question of Supply and Demand

24/11/2014 14:17 GMT | Updated 24/01/2015 10:59 GMT

If you sit in a pub with a bunch of single women of a certain age and they're talking about men, the common refrain will be that there are hardly any good men, the ones they fancy won't commit and the best are already taken. Men - of any age - seem mostly concerned with getting into women's knickers. Ok yes, there are lots of exceptions but you know what I mean; for most men getting a variety of sex presents more of a challenge than they would like. The point is, at some point both genders think they're at a disadvantage, women in getting commitment, men in getting sex, and neither sex get enough of what they want.

So what is the truth of the matter? Is it harder for men or for women? Who has the upper hand? According to newly published research, which sex gets its own way is a question of supply and demand.

The attitudes, behaviours and desires people have when it comes to sex can be described by a measure called sociosexuality. If you have a high sociosexuality score you're more likely to jump into bed with someone, you might have several lovers on the go at once, love isn't a prerequisite for sex and you're likely to have a varied sexual history. People with lower sociosexuality scores are more restricted in their sexuality and demand commitment before getting down to it. Men tend to have higher scores, particularly when it comes to attitudes and desires but there's a huge overlap of scores for men and women.

So, evolutionary psychologist Michal Kandrik and his colleagues at the University of Glasgow decided to track down the environmental predictors of sociosexuality by examining how men's and women's scores related to a variety of indices across all US states. 3209 women and 1244 men from across the country completed surveys on different aspects of their sexual behaviour, attitudes and desires and the analyses revealed that while women's sexual desires were affected by measures of health, and those of both men and women related to wealth indices, the only predictor of overall sociosexuality in both sexes was the scarcity or abundance of female mates.

What they found then was that when men outnumber available women of reproductive age, women get to call the shots and tend to demand long term, committed relationships - this makes sense since women are the ones who can get pregnant and can benefit from the help and investment of a partner. Men have to fall into line and provide women with what they want or risk foregoing sex altogether, thus we get low average sociosexuality all round.

Of course the reverse is also true. Where men are in short supply, they have the freedom to do as they want, and what they want is often casual sex with a variety of partners. This is when marriageable men become hard to find, and women find themselves in short term relationships whether they like it or not.

So it seems there is a general rule that the gender in short supply is the one with the most bargaining power.

In his book Where Have All the Liberals Gone? Race, class and ideals in America, James Flynn suggests that the fact that a large proportion of black American children grow up without a father comes down to the sex ratio in their society. This is because, he says, in some areas many black American men end up dead or in jail, and while some black men marry white women it's rare for black women to marry white men. This leaves black women with slightly more than a 50:50 chance of finding a man to get together with, and by the age of 19, 26% of black American women are single mothers. But if we look at Hispanics in the US, it's the women who have the mating market in their favour. Massive immigration of Hispanic men mean that there are 96 potential husbands for every Hispanic woman and Hispanics are the only US racial group where more men than women have a positive attitude to marriage.

So now you may be wondering where you can find the best sex ratio. Clearly several things have an effect on the number of available partners of the opposite sex but as a general rule, cities tend to have more women while rural areas have more of a concentration of men.

Spare a thought, for example, for the little Australian outback town of Mount Isa, where there are lots of blokes, even more sheep, and not very many sheilas. Things were getting so bad a while back that the town's mayor put out a plea to even less-than-attractive women to come forward: "If there are five blokes to every girl we should find out where there are beauty-disadvantaged women and ask them to proceed to Mount Isa," he said.

Quite. But according to some, the local male talent might not really be worth the move to the outback, 'beauty-disadvantaged' or not. As one single woman newcomer to the town said,

"We've got a saying up here: the odds are good, but the goods are odd."

Head across country though and it's a different story. In the metropolis of Sydney it's the men who are in short supply and especially when women get into their 30s the pickings are slim as, according to one single male immigrant, all the guys are either married or gay. He's having a fine time though; for him it's the best city on earth and he's never going home.

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