Culture Has More To Do With Promiscuity Than Evolution

By Megan Carpentier | April 24, 2009 | 7:00pm

The idea that men try to impregnate as many women as possible while women try to hold on to a provider is derived from fruit fly behavior. Its applicability to humans is becoming increasingly questionable.

The initial study was conducted in 1948 by Angus J. Bateman, who showed that female fruit flies had fewer mating partners and their overall offspring had less genetic diversity than male fruit flies’ overall offspring.

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Bateman concluded that, because a single egg is more costly to produce than a single sperm, the number of offspring produced by a female fruit fly was mainly limited by her ability to produce eggs, while a male’s reproductive success was limited by the number of females he inseminated. These studies supported the conventional assumption that male animals are competitive and promiscuous while female animals are non-competitive and choosy.

No one disputes the accuracy of Bateman’s work, just its indiscriminate application to human behavior without any regard to social of cultural factors. A new study by Dr. Gillian R. Brown at the University of St. Andrews seeks to provide more depth to our understanding of human sexuality.

“The conventional view of promiscuous, undiscriminating males and coy, choosy females has also been applied to our own species,” says lead study author Dr. Gillian R. Brown from the School of Psychology at the University of St. Andrews. “We sought to make a comprehensive review of sexual selection theory and examine data on mating behavior and reproductive success in current human populations in order to further our understanding of human sex roles.”

That’s a rather generous explanation for the acceptance of a model that conforms to cultural norms and expectations of men and women’s roles in society and reinforces the idea that women who aren’t seeking to settle down with one sex partner are somehow dysfunctional, but ok.

Brown’s study, as The Telegraph reports, actually looks at, you know, human behavior.

The study of more than 10,000 people in 18 countries seems to throw on its head the generally accepted expectations that men tend naturally towards promiscuity and women are more particular when it comes to choosing a mate.

Hooray!

What else does it say? Plenty, according to Live Science writer Sally Law.

However, Gillian R. Brown, a professor at the School of Psychology at the University of St Andrews and the study’s lead researcher, says that the research also found big differences among populations on the patterns of reproductive success for men and women.

For example, the study cites societies in Botswana, Paraguay and Tanzania in which women – not just men – conceive children with multiple partners.

As is sometimes the case even in America, what with divorces and single parenthood not exactly out of the question.

But there’s more!

“Evidence for sex differences in variation in reproductive success alone does not allow us to make generalizations about sex roles, as numerous variables will influence [Bateman’s findings] for men and women,” Brown writes.

Population size is one such variable: both men and women will be selective about mates when there are lots of options – in a large city, for example. Conversely, neither gender will be choosy in low-population areas. In such a scenario, both men and women will take what they can get.

That probably explains why every woman in every major city I know complains about how their city is the worst to date in.

But Brown’s research does show that overall, across the 10,000 subjects in 18 countries, men tended to have more children by different women than women did by men. That, though, requires a fairly basic statistical explanation.

Brown’s research also addresses the issue of reproduction within a monogamous partnership; while only 16 percent of societies have monogamous marriage systems, they make up a large percentage of relationships in the developed world. In such societies, variances in male and female reproductive success were similar. Furthermore, in half of the world’s polygamous marriages – which account for 83 percent of the world’s societies – less than 5 percent of men take more than one wife.

You might be wondering why Brown only looks at reproductive success (the number of mates by whom people have children) versus the number of sex partners. Well, it turns out that’s because we all lie about it.

Here is why: the studies reporting these statistics are scientifically unsound, she said, which helps explain the mathematical difficulties in research that finds that men have more sex partners than women. (One such study, conducted by the National Center for Health Statistics, claims that men have an average of seven sex partners during their lifetime, while women have four.)

“[The reported numbers are] logically impossible if we’re assuming these are heterosexual interactions and that all individuals have been questioned,” Brown says. “We were particularly interested in asking whether the variance (not average) in mating success differs between men and women, but questionnaire studies don’t seem to be a sufficiently reliable source of evidence.”

In other words, men may be exaggerating upwards, but women are probably also exaggerating downwards, contributing to the expectation that men will have more sex partners and women fewer.

And it’s not just women who are being judged. The social expectation for men to sleep around — particularly in the developing world, where Brown’s research shows the greatest variance in reproductive success between men and women — is toxic for society at large and the people in it.

Newswire IRIN is running an interview with Purmina Mane, an executive director of the UN Population Fund, who says the idea that men should have multiple sexual partners, take risks, are resilient to disease, reject contraception and be too strong to ask for help continue to affect access to healthcare and reproductive health services and is increasing exposure to the HIV virus for both men and women.

“Late diagnosis and treatment means that many continue to practice unprotected sex, running the risk of reinfection and of unknowingly infecting their partners,” said Mane.

I guess the Pope’s abstinence-in-Africa-you-don’t-need-condoms is working?

Others agree with Mane.

The story also quotes Graca Sambo, an executive director of Forum Mulher, a women’s rights NGO in Mozambique, which said the idea that men should have many different sexual partners was a major contributing factor to the country having one of the highest HIV prevalence rates in the world – 16%.

“A lot of men have many sexual partners because this is what is expected of them,” she said. “Masculinity is very much instilled by culture and by tradition, which say that men have to be studs.”

Which, of course, backs up Brown’s findings that promiscuity in men is by no means biological — but it does fit into preconceived notions about expected and appropriate behavior for men and women, which, it turns out, is good for none of us.

Evolution Of Human Sex Roles More Complex Than Described By Universal Theory [EurekAlert]
Men Are No More Promiscuous Than Women, Survey Finds [Telegraph]
Basis for Male Promiscuity Questioned [Live Science]
How Can We Change ‘Macho’ Attitudes To Sex? [The Guardian]