Gender equity can cause sex differences to grow bigger

1960 Le Lac des cygnes ballet - Jean-Paul Andreani and Claire Motte performing on stage at Opera de Paris.  Credit: Christjeudi10, Wikimedia commons
1960 Le Lac des cygnes ballet – Jean-Paul Andreani and Claire Motte performing on stage at Opera de Paris. Credit: Christjeudi10, Wikimedia commons

How do sex differences arise? Few questions animate as much disagreement and contention, in everyday society and in academic study. For as long as the question has been asked, the answers have fallen between two extremes: sex differences arise innately, or they come from social experience.

That same polarity defines much of the study of human behaviour and society, and has done since the ancient Greeks asked whether ideas arose innately (Rationalism) or from experience (Empiricism). The modern fault-line runs deepest between rationalist biology and empiricist socialisation.

Impossible as it might seem for any serious thinker, awake and aware and living in the current Century, to dismiss either biology or socialisation, you might be surprised. Dogmatism and ignorance still stifle the study of human behaviour, and the topics of gender and sex differences in particular. And the lay public is equally awash in tightly-held, but often flimsy ideas about how women and men come to differ, on average, in all sorts of traits.

The evidence is in: samples of women and men differ, on average, in a vast number of personality, emotional, behavioural, cognitive and attitudinal measures. Yes, the sexes overlap. And one cannot and should not rush to inferring anything about a person from the average properties of those who share the same genital configuration. But sex differences are present, found in many replicate studies, and often similar in magnitude across societies.

Rationalist biology holds that such differences have evolved. The combination of traits that made our male ancestors successful fathers differ from those that turned our female ancestors into successful mothers. This idea chimes with the repeated presence of so many sex differences across cultures, but the fact that the magnitude of the differences varies considerably among cultures suggests much more than biological determinism.

The Empiricist thinking that has dominated the study of gender in the social sciences for more than half a century holds that sex differences arise from extensive socialisation, and differences in the power that women and men hold and wield. This view brings us the notion that by ceasing to socialise boys and girls into stereotyped sex roles, and breaking down power inequities within societies, sex differences will diminish.

The idea that teaching, socialisation and structural change will progressively erode sex differences and gendered behaviour has a powerful hold. It underpins social interventions from “No Gender December” (a.k.a. the Christmastime war on pink toys) to the current Stop it at the Start campaign against domestic violence.

Stop it at the Start video, part of an Australian Government campaign to combat domestic violence against women.

A testable prediction

A recent book chapter by eminent evolutionary psychologist David P. Schmitt adds an interesting dimension, sure to be controversial, but also with considerable potential to rejuvenate debate. The book, The Evolution of Sexuality (Springer, editors Todd K Shackleford and Ranald D. Hansen), at US $139 will likely prove inaccesible to readers without access to an academic library.

Alice Eagly, Wendy Wood and Mary Johannesen-Schmidt, among the most persuasive advocates for the primacy of socialisation into sex roles, predicted that increasing gender equality would lead to “the demise of many sex differences”. That prediction seems so intuitive, so consistent with contemporary thinking about gender equity, that it hardly needs testing. But Schmitt didn’t think so. He recognised that not only should the idea be put to the test, but that there exists a wealth of data on cross-cultural on variation in personality, behavioural and other traits that could be matched with good measures of gender equity and sex role ideology.

Counter to the prediction of social role theory, in only 2 out of 28 traits examined by Schmitt did sex differences narrow as gender equity increased. In six traits, the sex difference remained stable, and in 20 traits it widened.

For example, women tend to score higher than men on personality tests for extraversion, agreeableness and conscientiousness. Gender equity tends to elevate all three of these traits, but it does so more in women, widening the average sex difference.

Likewise, men score higher than women for the “Dark Triad” traits of Machiavellianism, Narcissism and Psychopathy. Gender equity has the salutary effect of reducing each of these three rather nasty traits, but it does so more for women than for men, resulting in wider sex differences.

The two traits in which gender equity narrowed sex differences are instructive, too. Women are more likely than men to value resources and wealth in a mate. Gender equity reduces this preference, but does so more in women, narrowing the sex difference. And men tend to report a more unrestricted sociosexuality – fantasising about, attitudes toward and engaging in uncommitted sex – than women do. Sexuality grows less restricted with gender equity in both sexes, but more so in women, again narrowing the sex difference.

The narrowing of sex differences in preference for wealthy mates and sociosexuality are to be expected, and very much in line with the politics of sexual and domestic liberation. This is exactly what any observer of contemporary society would have expected, irrespective of the moral valence they give to the issues involved.

Many behavioural traits showed general changes for the better with increasing gender equity. Personalities take on more socially desirable forms. Couples emphasise love within their romantic relationships. Intimate partner violence declines. And rates of depression decrease. And yet the fact that sex differences in so many of those traits increased opens up considerable new space for empirical study, and for us to question dogma and doctine of all kinds about how sex differences arise.

This study is just a start. There remains some way to travel if we are to make stronger inferences about causation. But it is worth wrapping our head around the paradox that moves toward gender equity in opportunity, including the dismantling of patriarchal power structures, might, paradoxically, also widen sex differences.

Bohemian Like You, the Dandy Warhols.

The Conversation

Rob Brooks, Scientia Professor of Evolutionary Ecology; Director, Evolution & Ecology Research Centre, UNSW Australia

This article was originally published on The Conversation. Read the original article.

How often does Donald Trump wash his hands?

How clean is that finger, Donald?
How clean is that finger, Donald?

Move over Nate Silver! The statistician and author of The Signal and the Noise: Why So Many Predictions Fail – But Some Don’t may have called 49 out of 50 states right in the 2012 US Presidential election. But today I note that my predictions for the 2014 mid-term elections were 100 percent correct.

Mostly, that’s because I made only one. But it was a goodie. Noting the hysteria that then abounded about the West African Ebola outbreak, I predicted that it would propel a rightward swing in the mid-terms.

One might expect that an epidemic limited almost entirely to West Africa should be way, way down on the list of factors likely to swing American voters. What with ISIS, the economy, Obamacare, abortion and so many other issues of greater direct relevance to the United States.

But a spectacularly scary hemorrhagic fever outbreak – ravaging countries a mere single plane flight from the USA! – holds the potential to propel a rightward swing next Tuesday.

Readers of this column will know of my obsession with understanding how evolved psychological traits shape ideological and political differences. My Elections in the Time of Ebola column drew a link between heightened disgust sensitivity, outgroup fear and conservative voting intentions. Noting the U.S. media’s apparent terror of Ebola reaching American shores (rather than, say, visiting horrific hemorrhagic death on hundred, and displacing or inconveniencing hundreds of thousands of mostly poor Africans), I suggested that keeping Ebola fears foremost might flush out the right-wing vote.

Turns out that’s exactly what happened. Psychological Science just published a paper by Alec T. Beall, Marlie K. Hofer and Mark Schaller with the captivating title Infections and Elections: Did an Ebola Outbreak Influence the 2014 U.S. Federal Elections (and if so, How)?. Schaller was the first to propose the crucial, to that time unexpected, links between disease, disgust and political traits like outgroup fear and conservatism. And his group lead the world in studying not only the links but the psychological basis for those links.

Outbreak

The 2014 Ebola outbreak began in Guinea, and first gained international attention in March 2014. Six months later, the outbreak was ravaging West Africa, and flaring up in other parts of the world. On September 30 2014, The US Center for Disease Control confirmed that a man who had traveled to Dallas, Texas from Liberia had Ebola. He subsequently died, and two nurses who had treated him were infected but recovered. And on 23 October, Craig Spencer, a Medicins Sans Frontieres doctor who had cared for Ebola victims in Guinea became the fourth and last case in the US ‘outbreak’.

Once the CDC announced that Ebola had made it to the U.S.A., media coverage there intensified and people grew markedly more concerned about the possibility of an epidemic. Beall, Hofer and Schaller recognised the importance of this transition, and so they analysed polling trends from September and October, as well as the volume of Internet searches for the term “Ebola”.

Interestingly, after the first of October, once the possibility of an Ebola outbreak in the USA became more salient, voters’ intentions swung discernibly toward Republican candidates. And the more voters searched for “Ebola”, the stronger the change in their voting intentions.

Interestingly, people’s concerns about Ebola appear to have influenced voting intentions in states that traditionally favour Republican candidates, but not in those that predictably vote Democrat. One might expect conservative politicians to play up disease fears particularly strongly within conservative electorates that appear to be flirting with swinging left.

Politicians should have clean hands
Politicians should have clean hands

The Hands of The Donald

Fortunately for West Africa, and for progressive politicians in general, the Ebola outbreak is largely over. That won’t stop politicians from appealing to voters’ basest fears. Donald Trump has done so shamelessly in his claims that Mexican immigrants bring “tremendous infectious disease … pouring across the border”.

From Vanity Fair editor Graydon Carter’s repeated characterisation of Trump as a “short-fingered vulgarian” to Marco Rubio’s desperate attempts to imply a Trumpish deficiency in the penis department, Trump’s hands get a lot of attention. So much so that he recently saw fit to defend his own hands
in an interview with the The Washington Post’s editorial board:

“Normal,” the Republican presidential front-runner insisted. “Strong.” “Good size.” “Great.” “Fine.” “Slightly large, actually.”

Perhaps it isn’t the size of his hands that matters in this election. Perhaps we should be paying attention to how clean he can keep them?

AC/DC “Dirty Deeds (Done Dirt Cheap)” Live at the River Plate.The Conversation

This article was originally published on The Conversation. Read the original article.

Life’s short, have you had an affair?

Today, millions of very nervous adults are furtively checking sites like “Have I been Pwned” to check if their account details at Ashley Madison have been leaked. Others are checking if their partners or acquaintances had accounts. The hacking and subsequent release of data from the world’s biggest infidelity-focussed dating service continues to reverberate, provoking an interesting suite of ethical questions.

Unless you’ve confined your news intake to re-runs of Jarryd Hayne’s BIG MOMENT in a trial game for the 49ers, you will be well aware that a group calling themselves Impact Team hacked the systems of Avid Life Media (ALM), who operate a number of sex and dating websites. Impact Team threatened to release sensitive information about users unless ALM close down Ashley Madison, which specialises in connecting people looking to have extra-relationship affairs, and Established Men, which they argue is a “website for rich men to pay for sex”. Established Men, understandably, puts it a little more gently: “connecting young, beautiful women with interesting men”.

Shhhhh! Ashley Madison screenshot.
Shhhhh! Ashley Madison screenshot.

So much for the libertarian hacker stereotype. Impact Team are waging a moralist crusade against both the websites themselves, and the people whose extra-marital or transactional sex shennanigans the websites enable.

Neither website has been shut down and yesterday Impact Team uploaded information about over 30 million users, including their email addresses. Security experts quoted in news outlets seem to agree that the data dump is genuine.

The media coverage has varied from titillating attempts to dissect where the “cheating” hotspots are to the very real personal stories of spouses who’ve been busted. Sydney radio station NOVA even tried, and rather spectacularly failed, to turn it into edgy commercial radio, searching the database on behalf of callers. They very quickly learned how spectacularly bad their idea was when they found the husband of one of their callers was indeed subscribed to Ashley Madison.

Nobody wins here. The whole business reeks of weakness and failure. As Gaby Hinsliff put it in the Guardian,

it’s hard to decide which of the activities involved – cyber blackmail, building a business on wrecking marriages, or just good old-fashioned philandering – is least charming.

More than gossip

But some people seem bouyed by the whole business. I’m intrigued by the level of schadenfreude; so many people are relishing the slow implosion of Ashley Madison and the exposure of millions of people’s most embarrassing intimate details. What disappoints me most is how the exposure of 30 million people is being shoe-horned into a one-size-fits-all view of sex and relationships. How this is all about “cheating”, and that infidelity means the same thing in every relationship.

We might not like to admit it to ourselves, but relationships differ enormously from one another. So do the reasons people have sex, both within and outside of committed relationships. Yes, a great many – probably most – Ashley Madison clients were furtively seeking extra sexual partners without the knowledge and consent of their long-term partners. And many did so despite their relationships being otherwise functional, productive and respectful. This kind of infidelity has its victims: the partners who remain at home, pouring their selves into the shared enterprise of coupledom, unaware that the other party isn’t matching their effort and commitment.

According to Leonard Cohen (Live in London), “Everybody Knows that you’ve been faithful. Give or take a night or two”.

And yet nobody can properly evaluate another’s relationship from outside, much less 30 million relationships. The evolutionary sciences continue to show that humans have a marvellous capacity to form loving, cooperative relationships, to remain sexually faithful to one another, and to work hard to build both families and wealth. Marvellous as those relationships can be, profound as the love that binds us together might feel, not all relationships remain functional.

One of the less-explored dimensions of the Ashley Madison schamozzle is the fact that many people had quite defensible positions for looking outside their relationships. Their current relationships might be loveless, sexless, dysfunctional, exploitative or even abusive. They may be in the process of coming out to themselves, facing the daily dissonance of being gay in a straight marriage.

A great many people are trapped by economic circumstances and questions of child custody in hellish relationships. Who would deny those people the chance to connect with another, perhaps to find the courage or even the ally they need to escape, or perhaps to enjoy being loved, appreciated and getting properly laid?

How many people, whose names appeared on that database last night, had to go home to their controlling, jealous, or abusive partners? How many people, living straight lives, many in countries where homosexuality is illegal and harshly punished, were outed by Impact Team’s self-righteous moralism?

Beyond the many dysfunctional relationships from which affairs might offer respite or escape, the Ashley Madison affair forces us to confront even more uncomfortable realities about relationships. Even “a mommy and daddy who love each other very much” are likely to find that they cannot be everything one another needs. Our evolved capacity to be really quite good at monogamy has its limits. We have also evolved, thanks to our ancestors’ tastes for sexual intrigue, an exquisitely context-dependent capacity to throw off the shackles of monogamy when it suits us. It takes a spectacular denial of human nature to believe that life-long heterosexual monogamy represents some kind of social zenith and that deviations from this one true path represent deep aberrations.

On-line dating has imposed what economists call a “technological shock” on the mating market, reshaping how people meet, court and, ultimately, mate. Ashley Madison’s success, and the marketing genius behind it’s quasi-inspirational slogan (“Life’s short. Have an affair.”), reshaped the extra-couple mating market. And the realisation to which so many customers are waking today, that even a website set up to guarantee discretion in extracurricular hooking up is vulnerable to hacking and public shaming, will change the dynamics of sex once again.

I would be disappointed if the whole business turns into a witchhunt on “cheaters”, if we slide back toward the puritanism that had Hester Prynne wearing the Scarlet Letter. Perhaps we need to embrace the messier, more complex reality that sex does not equal love, and love does not always mean exclusively and forever. Our relationships are negotiated every day in the way we treat one another and accept our partners, and lovers, as they are, rather than packing them into the neat box of a one-size-fits-all relationship.

The Conversation

Rob Brooks is Scientia Professor of Evolutionary Ecology; Director, Evolution & Ecology Research Centre at UNSW Australia

This article was originally published on The Conversation. Read the original article.

Early bird gets the sperm … to the egg

What gets you out of bed in the morning? Before morning has broken, and some time before blackbird has spoken, songbirds rise for sex. And a clever new experiment reveals just how important it is for male songbirds not to sleep in.

A great many species of songbirds nest in pairs, presenting to the world a facade of monogamy. Until the 1990’s, songbirds were rhapsodised by social conservatives as paragons of family values, mother and father working together faithfully to fledge their demanding chicks. Until new genetic technologies revealed that most socially monogamous birds were playing a lot of away games.

For a long time, ornithologists failed to spot the shennaniganising because most of it happens just before dawn, when even the hardiest birdo is still rubbing sleep from their eyes. That’s actually a bit unfair: ANU’s Professor Andrew Cockburn and his many collaborators have risen unspeakably early for decades to study Australia’s superb fairy wrens, revealing them to be Olympic medallists of extra-pair sex. Female wrens leave the nest before dawn, heading straight to males singing in the dawn chorus.

This kind of behaviour gives male birds two reasons to rise early: to prevent their social mate from mating with another male, and perhaps to get a little bit on the side from some other male’s social mate. European blue tit males who start singing early in the morning sire more chicks with other females, chicks he doesn’t have to raise because the female and her social mate do all the heavy lifting.

No wonder those Three Little Birds were cheerful when Bob Marley rose and smiled with the rising sun!

Consequences

But how do early and late risers do with their social mates? A team based at the Max Planck Institute for Ornithology in Radolfzell, Germany, found an ingenious way to answer this question.

By inserting slow-release melatonin implants beneath the skin of free-living male Great Tits, just before the breeding season, they tweaked the birds’ circadian rhythms. The body releases the hormone melatonin at night, and animal circadian activity patterns are cued by melatonin levels. Nocturnal animals are stirred into activity and dirurnal animals to sleep by rising melatonin.

Early rising male Great Tits can get the sexy stuff over with and spend the res of the day looking fabulous. Israel Gutiérrez/flickr
Early rising male Great Tits can get the sexy stuff over with and spend the res of the day looking fabulous. Israel Gutiérrez/flickr

Male great tits in the control group became active about 22 minutes before dawn, but those with melatonin implants took an extra ten minutes to get going. They were no less active during the day, and they stopped for the night at the same time, a few minutes before dusk.

But those extra ten minutes cost the males dearly. Twelve percent of chicks fledged from the nests of control males were sired by another male, but 42 percent of chicks in the nests of melatonin-implanted males had been conceived with another male’s sperm.

As an early riser, I’d like to claim victory for the early birds at this point. But of course I can’t. For humans, Sex at Dawn remains niche. Many even prefer to rise early for bird watching.

The night time is where the action is for our species. Night owls tend to be more extrovert, novelty-seeking, and night-owl men (but not women) report having more sexual partners. Night-owls are more likely than early risers to be single and open to short-term commitment-free sex. Being a night owl is associated with risk-taking in women on a levels similar to males (both night-owls and early risers). Risk-taking predicts short-term sexual behaviour, suggesting that female night owls might be especially oriented toward sex.

Interesting, it’s true, but not yet the basis for any firm prescriptions. Unless you’re Charlotte Alter writing at Time Magazine. Anybody spot the implicit bias and rampant earlybirdophobia?

Women who stay up late are more likely to get laid, but less likely to get married than women who get up early to do a sun salutation or whatever.

Whatever indeed!

Up all night to get lucky? Thank you Daft Punk!

The Conversation

Rob Brooks is Scientia Professor of Evolutionary Ecology; Director, Evolution & Ecology Research Centre at UNSW Australia

This article was originally published on The Conversation. Read the original article.

Violence: blaming the bloke but not the booze

“Spoiling for a Bar Fight” Jonathan Cohen/Flickr, CC BY-NC
“Spoiling for a Bar Fight” Jonathan Cohen/Flickr, CC BY-NC

Is alcohol-fuelled violence caused by the booze itself or by the macho culture in which the drinking occurs? If we are to believe a recent study commissioned by the alcohol company Lion, it’s the culture that’s to blame. That’s a rather convenient conclusion for the alcohol industry. But it hinges on a fallacy and has the potential to cause much damage.

The study was conducted by Dr Anne Fox, consultant anthropologist and founding director of Galahad SMS Ltd (SMS stands for Substance Misuse Solutions) who studies drinking cultures. Fox has been promoting her report in the broadcast media and op-eds, pushing her conclusion that

It is the wider culture that determines behaviour while drinking, not the drinking per se. While there are very good health reasons to reduce excessive drinking, you must influence culture if you want to change behaviour.

The Lion and the Fox

Fox’s report reads as a series of anecdotes and quotes, gathered during discussions with drinkers in a variety of situations, workers in bars, taxi drivers, police, emergency workers, government officials and various other people. Fox’s observations are organised thematically, interspersed with folk-evolutionary speculation of the following kind:

Could ritualised drunken behaviour be a re-enaction of an evolved ancient need for joyous bonding that still persists? Given what we know about alcohol and the brain, and the evolution of the brain itself, the question can at least be asked.

And simplistic characterisations of national drinking cultures, such as:

Spaniards and Italians … are culturally much more emotionally extroverted and do not associate alcohol so much with romantic or sentimental expression.

There is no attempt to grapple with numbers surrounding violence, or the consumption of alcohol. In fact there seems to be no way of sifting evidence with any kind of fairness to the competing alternatives at all. Instead, as might be expected when a liquor company commissions an expert on ‘drinking culture’ to study what causes the violence that too-often erupts in and around venues where alcohol is served, the conclusions seems inevitable: you have to change the culture in which the alcohol is consumed.

And which aspects of culture are most in need of changing? Why, masculinity, of course. As Fox put it in the Sydney Morning Herald:

The way to tackle the real underlying causes of anti-social behaviour is to address the cultural reinforcers of violence, misogyny, and aggressive masculinity in all its cultural expressions from schoolyards to sports fields, politics and pubs, movies and media.

Who better to tie together alcohol, misogyny and high culture then Snoop Dogg? Gin and Juice (1993)

Could it work?

The Fox/Lion report reminds me of nothing more than the American gun lobby slogan that “Guns don’t kill people. People kill people”. By reducing the complex issues of gun-related homicide to two apparently contradictory alternatives, those most wedded to their right to bear arms find rhetorical – if not logical – comfort in blaming the shooter and not the weapon.

Having read the report, I think there are interesting observations about the relationships that Australians and New Zealanders have with alcohol, well worth injecting into the national debate on antisocial behaviour. But should we leap from observing that culture is important to focusing all interventions on the remodelling Austral masculinity? I’m sure the liquor lobby would like to do so, but I’m not the only one who disagrees.

Deakin’s Peter Miller has already published an excellent Fact Check on the Fox/Lion report, concluding:

It’s not correct to say you can’t “alter the culture of violence and anti-social behaviour in any meaningful way” by tackling the way people drink. There is a lot of evidence showing that changing people’s drinking hours and consumption patterns reduces violence and hospital admissions – which is a lot more significant than tinkering at the margins of culture.

Cultural creationist wishful thinking

It seems that those who study ‘culture’, that slippery omnipresence in which we all wallow, inevitably conclude that the only way to improve society is to change culture. Drain the toxically misogynist, masculine swamp, and replace it with a more rarified egalitarian pond, and everything will be okay.

Changing ‘culture’ isn’t easy. And it certainly amounts to far more than education campaigns, shaming and punishing bad behaviour.

Fox, to her credit, doesn’t insist on throwing out all biological insights. She recognises that night-time drinking among young people is about meeting evolved biological needs, for bonding, belonging and courtship. And that young men competing with men, and seeking to impress women are the well-spring of most of the anti-social behaviour.

Her report considers the example of Icelanders who consume more booze and own more guns, but do far fewer stupid, violent things per capita than Australians. She even recognises that Iceland’s low-levels of economic inequality remove some of the incentives for young men to pose, to impress, and to take out the competition.

If Australia wants to “change the culture” in which drinking takes place, it will have to change more than arbitrary social sanctions and “culturally constructed” ideas of what it means to be a manly man. If that is even possible. It will have to recognise that economic conditions, create the incentives for young men to strive, to compete and to take stupid risks.

And that means resisting the temptation to blame single causes. It isn’t just the booze, it isn’t just the blokes, it isn’t just the economy and it certainly isn’t just the culture. What matters is how those ingredients combine.

Perhaps we need to look more closely at the incentives for young men to strive and take risks. Eminem captures this in “Lose Yourself”.

The Conversation

Rob Brooks is Scientia Professor of Evolutionary Ecology; Director, Evolution & Ecology Research Centre at UNSW Australia

This article was originally published on The Conversation. Read the original article.

Can science finger a philanderer? Not like this!

Two left hands make a heart. Source: Leon Brocard/Flickr
Two left hands make a heart. Source: Leon Brocard/Flickr

Are people naturally monogamous, polygamous or promiscuous? It’s one of those questions that most people feel quite confident in answering. Ask a few people and you’re likely to come up with a variety of contradictory answers, each delivered with considerable confidence. But the question is far more slippery than it first appears.

I will return later to the question of humanity’s “natural” mating system, but lately I’ve been far more interested in why people hold such strong opinions on the subject. And I think it’s mostly out of keenness to understand ourselves and those we love, to navigate the perilous tension between monogamy and non-monogamy that runs through our own lives. And, often, to validate our own proclivities.

With the Hallmark Holiday of St Valentine’s Day just a few days away, a recent study that touches on the monogamy-promiscuity tension deserves close examination. Particularly because various media outlets made it sound like a litmus test of whether someone is a likely ‘strayer’ or a certain ‘stayer’.

Sociosexuality

In ‘Stay or Stray: evidence for alternative mating strategy phenotypes in both men and women’, Rafael Wodarski, John Manning and Robin Dunbar probe the statistical distributions of two traits related to sexual behaviour. They ask whether sociosexuality and the relative lengths of the second and forth fingers (2D:4D ratio) conform to distributions with one peak or two. A bimodal distribution, with two peaks, suggests there may be two different groups of individuals within a given sample.

An individual’s sociosexuality reflects how restricted their attitudes toward sex and their sexual behaviours are. Wlodarski’s team used answers from the following six questions in the 9-item Revised Sociosexual Orientation Inventory (SOI):

  1. With how many different partners have you had sex within the past 12 months?
  2. With how many different partners have you had sexual intercourse on one and only one occasion?
  3. With how many different partners have you had sexual intercourse without having an interest in a long-term committed relationship with this person?
  4. Sex without love is OK. (this and the next two questions answered on a scale from strongly disagree to strongly agree)
  5. I can imagine myself being comfortable and enjoying “casual” sex with different partners.
  6. I do not want to have sex with a person until I am sure that we will have a long-term, serious relationship.

High scores (plenty of agreeing, and lots of casual sex) characterise an unrestricted sociosexuality, whereas people with restricted sociosexuality tend to get low scores.

The statistical tests showed that within fairly large samples of British and American subjects, there was evidence that both women’s and men’s SOI scores are distributed bimodally. But there’s plenty of overlap between the peaks (modes). The authors infer that within each sex exists a more restricted, monogamous group of individuals and another group of unrestricted promiscuous people.

Here, and in almost every study using SOI, men tend to have more unrestricted sociosexuality than women, on average. The difference in means could be pinned on small differences in the percentages of men and women in the restricted and unrestricted SOI groups.

Digit Ratios

The group also analysed a sample of hand measurements of 1314 British subjects. They looked at the ratio of the index finger (second digit, or 2D) to the ring finger (4D). Adults who were exposed to higher levels of testosterone when they were in the womb, tend to have relatively short index fingers (small 2D:4D ratio).

Hand with index finger shorter than the ring finger, resulting in a small 2D:4D ratio, pointing to a high exposure to testosterone in the uterus. source: Wikimedia Commons
Hand with index finger shorter than the ring finger, resulting in a small 2D:4D ratio, pointing to a high exposure to testosterone in the uterus. source: Wikimedia Commons

Now that you’ve stopped looking at your fingers, can we move along?

Prenatal testosterone exposure is also thought to bias individuals toward more promiscuous sexuality when they reach adulthood. The pattern also works across species: monkey and ape species with long-term pair bonds and a knack for monogamy tend to have high 2D:4D ratios.

Interestingly, when Wlodarski’s team applied their statistical tests to the distribution of 2D:4D ratios, they again found evidence of bimodality. A similar pattern in two very different traits associated with promiscuity-monogamy suggested to them a provocative conclusion:

Perhaps we are dealing here with two different types of people.

What if some folks are good at monogamy whereas others are rather better at … the other stuff? Perhaps. Funny thing about sex research is that any conclusion you arrive at will leave some people feeling validated and an almost equal number something more like violated.

We go on foot from here

But the idea is worth exploring. The valuable thing about this study is that it challenges our too-common tendency to see every trait as a continuum, with a few individuals at either end and the majority somewhere in the middle.

Interestingly, the two measures, SOI and 2D:4D ratio were from different samples. At no point did the researchers provide any evidence that the two groups separated on digit ratio were the same individuals as those separated on SOI. They couldn’t be: they were different samples.

The links between SOI and 2D:4D ratios are, at best, equivocal. Some studies find that low 2D:4D is associated with higher SOI. Other studies fail to find such effects. And a study of women and men from Brazil and from the Czech Republic, found that in both sexes a more feminine (higher) 2D:4D ratio is associated with less restricted sociosexuality.

But you wouldn’t know it from the media coverage. The Daily Mirror over-promised, trumpeting that “Boffins” have learned “How to work out if your partner is cheating on you? Check their fingers.” Well, checking if they’ve been hiding their wedding ring might tell you something, but checking out their 2D:4D ratio won’t help at all. Nonetheless, Valentine’s Day dinners are going to involve a lot of quizzical staring at fingers this year. (And not out of daydreaming that he might just put a ring on it.)

The Telegraph took a more introspective line under the headline “Are you promiscuous or faithful? Measure your index finger to find out.” Actually, a better way to figure out if you are promiscuous or faithful, or if you are likely to be in the future, is to ask yourself the questions in the Sociosexual Inventory. It’s pretty straightforward: if you’ve had plenty of one-off sex and lots of partners in the last year, then odds are that you bend toward promiscuity. At least at this point in your life. But I can imagine folks on both side of the 2D:4D distribution reassuring themselves that they are doing the right thing.

Sometimes I wonder why scientists even bother talking to the media. The public love to learn the latest things that “boffins have figured out”, but they deserve journalism that makes at least a token effort to grapple with the research or speak to said boffins.

What are we?

The distribution of SOI and 2D:4D cannot tell us all that much about humanity as a whole, other than that both women and men vary in their openness to casual sex and their proportional finger length.

But this variation is part of what makes human sexual behaviour so fascinating. Some people do seem at ease with life-long monogamy whereas others are shockingly bad at it.

How that variation arises presents a very interesting bevy of questions. Cue the usual intellectually bereft wrangling over nature and nurture as though the two were alternatives.

I’m sure there is more than one reason, but an obvious candidate for variation in sociosexuality is religion. Perhaps those who buy in to religious practices are more likely to be on the “restricted” end of the sociosexuality distribution, whereas those who have rejected or never embraced religion are more likely to be in the “unrestricted” peak?

For now, my preferred answer to the question “Are people naturally monogamous, polygamous or promiscuous?” is “YES”.

We have evolved adaptations that make some of us rather good at monogamy, some of the time. Until we’re not. We also have an evolved capacity to leave one partner for another, or to partner up with more than one person at a time, depending on our circumstances.

If you’re looking for natural history to vindicate your own particular preferred way of life over the alternatives, then you’re always going to be disappointed.

Monogamy can be complicated too. The Police knew this. Check out “Wrapped Around Your Finger

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Economic dependence promotes prudishness

Stay home, bake whitebread, don't sleep around.
Stay home, bake whitebread, don’t sleep around.

Marriage, according to those who habitually preface the word with “traditional”, is a collaboration. With complementary roles, filled as predictably by one woman and one man as peanut butter fills the gap between two slices of white bread.

If you encounter somebody clinging to this view of marriage in which women happily traipse down the church aisle into economic dependence on their menfolk, then I’m sure you can predict their views on sex and the thousand other issues that inhere to sex:

Sex education? Abstain until marriage, ‘cos true love waits.

The pill? Okay if you’re using it to control your acne.

Abortion? Causes all those calamities the greenies like to pin on climate change.

Okay, my clumsy stereotype grows unkind. My point is that more often than not women’s economic dependence on men is bundled up with strong views against sexual promiscuity.

But why? Are economic dependence and anti-promiscuity morality both symptoms of the same cause? Patriarchy, perhaps? Or does one bring about the other? A new study in Archives of Sexual Behaviour suggests that economic dependence might lead to anti-promiscuity views.

Paternity no laughing matter

Visiting friends or relatives in the neonatal ward isn’t the place to crack jokes about paternity. In fact, most people, especially relatives of the new mum, go to great efforts to comment on the newborn’s likeness to the guy who thinks he’s dad.

Paternity stikes such a raw nerve with men because they can never be truly sure that they’re the father. At least they couldn’t until recent technological developments in DNA analysis made it possible.

And yet throughout our evolutionary past, some men thought they were working hard to raise their own genetic progeny where they were actually rearing the young of another. Men who were suspicious, jealous and not prepared to raise another man’s children might not have won any nice-guy prizes, but they did ensure their hard work contributed to the success of their own genes. Including any genes that disposed them to jealousy and vigilance about paternity. Unfortunately, we are all descended from many such men.

Today, humanity’s long history of insecurity over paternity can be seen in the politics of paternity testing and the undignified squabble over how many children are really sired by someone other than dad.

Sensitivities over paternity have shaped religious practices, laws, customs for the inheritance of wealth, and behavioural norms.

In their pop bestseller Sex at Dawn, Christopher Ryan and Cacilda Jethá argued that sexual jealousy and paternity insecurity are newcomers to human society, almost unknown in our species’ long hunting and gathering past where love flowed more freely and couples stayed together only briefly. The economic changes wrought by farming tied families to the land, necessitating cultural innovations to ensure wealth and land stayed within the family.

Ryan and Jethá make several mistakes, including unduly romanticising our hunter-gatherer ancestors, and viewing culture as something separate from biology. The cultural practices that surround fidelity and conception are more usefully viewed as extensions of men’s evolved paternity insecurity. And the scale of those extensions varies among places and over time.

When to worry about promiscuity

When women depend economically on their husbands or partners, then both women and men should value paternity certainty more highly. Men working hard to raise a family have plenty to lose in evolutionary terms if the children they raise are actually sired by somebody else. When men don’t do much for their partners or the offspring, they should be much more chilled about paternity, and thus much more relaxed about sexual promiscuity.

Likewise, when a woman depends heavily on a man’s labour, or the money he brings in to the household, then the cost of losing him is much greater. There are two ways she might lose him through extra-pair sex: if he has other sexual relationships he could run off with one of the other women, leaving his existing family in the lurch. But when she has extra-pair sex and gets busted, she might lose him. Or worse. Jealousy can trigger psychological abuse and violence.

In the recent paper that inspired this column, psychologists Michael E. Price, Nicholas Pound and Isabel M. Scott, from Brunel University in the U.K., sought to test the links between women’s economic dependence and both women’s and men’s attitudes to promiscuity.

From online surveys of more than 5000 Americans, Price and his colleagues showed that when the women in a subject’s social network depend economically on men, then subjects tend to judge promiscuity more harshly. And the effects weren’t spurious consequences of religion, or ethnicity or political conservatism. When they fitted these other variables into their statistical tests, the association between female economic dependence and opposition to promiscuity remained.

Price also asked whether the association arose as an artifact of geography: Texas and Utah, for example differ culturally on questions of morality and gender roles from, say, Massachusetts or California. States in which women earned more were also more relaxed about promiscuity. And this result arose out of the effects women’s earnings had on female economic independence.

Even more compelling, by comparing the attitudes of geographic neighbours, in the same or nearby zip codes, Price and his colleagues found that the association held. Irrespective of where you live, the economic dependence of the women a person’s social network predicts how they feel about promiscuity and non-marital sex.

We’ve known for some time that variation among societies in sexual morality is associated with variation in gender roles and, especially, earnings. The exciting development is how the new research suggests the patterns emerge from the bottom upward, with individual attitudes being shaped by prevailing economic circumstances in their close social network. At least in part.

I’m interested to know what the authors think about the relevance of their data to Roy Baumeister and Kathleen Vohs’ ideas on sexual economics in which women restrict the supply of sex under circumstances when they have the most to gain from a high price. This interpretation is not inconsistent with Price et al’s arguments about paternity certainty. But high female economic dependence presents exactly the kind of economic situation in which women need to drive a hard bargain in the sexual marketplace. Intriguingly, women took stronger anti-promiscuity stances, on average, than men did.

There are so many studies I would like to see done with a view to teasing out the causal relationships, and how attitudes to promiscuity change in the headwind of religion and other cultural forces. But this finding explains much about some of the trickiest ideological differences both within and among societies.

It could explain how economic changes since the Second World War paved the way for the sexual revolution. And why conservative politicians, especially in the U.S.A. seem equally hung-up on sexual liberty and the growing proportion of breadwinner moms.

And it may form an important ingredient in the ever-growing and dangerous ideological chasm between patriarchal theocracies and more gender-egalitarian democracies.

Thom Yorke singing Radiohead’s True Love Waits

P.S. I always relish seeing how other media cover research concerning issues touching sexual morality. According to “News Staff” at Science2.0, “If women want their promiscuity to be accepted they have to earn more money say evolutionary psychologists”. Keith Perry of the Telegraph reckons “Promiscuous women more likely to be tolerated if they are high earners”. And Lydia Smith, writing in the International Business Times got even more pithy, declaring “Only poor women are branded sluts”.

These were the first three links to news stories that popped up on Google. Not one headline reflects the real message of the study, but they all find a short path to slut shaming. For the record, the study tracked attitudes to women’s and men’s promiscuity.

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Rob Brooks does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

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Worse than sex? M is for May and for Masturbation Month

Workers of the world can have their International Labour Day, or Workers Day or whatever. But the month of May belongs to an equally fundamental dignity: masturbation.

The fact that a whole month is devoted to self-pleasure raises two important questions: who decides these things? And what are people meant to do over the 11 months from June to April?

On the latter, it seems that anyone can declare a day, a month or even a year be dedicated to a particular cause. The UN endorses some of these. Last year, 2013, for example was both the International Year of Water Cooperation and the International Year of Quinoa. Oh yes it was!

Perhaps I needn’t say it, but International Masturbation Month has not been recognised by the UN. Yet.

Like many ideas surrounding sex, Masturbation Month is American. Formerly “National Masturbation Month”, it did not require Republicans and Democrats working “across the aisle” to enact a special law. It only took a unilateral declaration of self-service by Good Vibrations sex shop in response to the firing of US Surgeon General Jocelyn Elders.

Elders’ dismissal followed comments at the UN World AIDS Day in 1994. Asked whether promoting masturbation might discourage school-age children from riskier sexual activity, Elders agreed, noting that children should be taught that masturbation is a natural part of human sexuality.

Conservatives, already outraged by her progressive views on abortion and drugs, construed her as saying masturbation should be taught in schools. An embattled President Clinton, whose own seed-spilling later sucked the life out of his own presidency, saw this as a step too far.

So, in Elders’ honour, Good Vibrations says:

We started National Masturbation Month – now International Masturbation Month with people celebrating across the globe! – to raise awareness and to highlight the importance of masturbation for nearly everyone: it’s safe, it’s healthy, it’s free, it’s pleasurable and it helps people get to know their bodies and their sexual responses. Of all the kinds of sex people can have, masturbation is the most universal and important, yet few people talk about it freely – worse, many people still feel it is “second best” or problematic in some way. Masturbation Month lets us emphasise how great it is: it’s natural, common and fun!

Politics of the pull

The US political battle over masturbation that led to Elders’ firing nearly two decades ago represents one minor shift in a centuries-old ideological tug-of-war over self pleasure.

The history of attitudes to masturbation makes fascinating reading, from the Egyptian god Atum who masturbated the universe into being and then, generously, continued to control the Nile’s flooding by his ejaculations, to the rather athletic how-to instructions provided in the Kama Sutra.

The cover of the 1875 Italian version of Samuel Auguste André David Tissot’s pamphlet “Treatise on the Diseases Produced by Onanism”. Source: Wikimedia Commons, Photograph by Giovanni Dell’Orto
The cover of the 1875 Italian version of Samuel Auguste André David Tissot’s pamphlet “Treatise on the Diseases Produced by Onanism”. Source: Wikimedia Commons, Photograph by Giovanni Dell’Orto

The Judeo-Christian tradition has usually not embraced, and occasionally condemned, the solitary vice. But things got seriously weird in the 18th century, when masturbation attracted the blame for all manner of evils and ailments. One early pamphlet, published anonymously, really says it all in the wonderfully descriptive title: Onania, or the Heinous Sin of self-Pollution, And All Its Frightful Consequences, In Both Sexes, Considered: With Spiritual and Physical Advice To Those Who Have Already Injured Themselves By This Abominable Practice.

Nineteenth century quacks such as Reverend Sylvester Graham lectured against the dire health consequences of “venereal excess” and the corrupting evils of self pollution. His health advice looks, today, like common sense: exercise, bathing, brushing teeth, drinking clean water and a diet of mostly vegetables and whole grains.

Visionary as he was, he is remembered because the bland diet he promoted, and the whole-wheat Graham cracker he invented, were designed to dampen libido. Likewise, the equally odd Dr John Harvey Kellogg proclaimed: “if illicit commerce of the sexes is a heinous sin, self-pollution is a crime doubly abominable.” Masturbation is worse than sex? Not as good, maybe, but worse? Kellogg’s lasting contribution to suppressing libido was the insipid corn flake.

And it wasn’t only the self-abuser who was in line to suffer. In “What a Young Woman Ought to Know”, Mary Wood Allen councilled young ladies to consider the fate of their as-yet unborn offspring. Does this sound familiar?

The results of self-abuse are most disastrous. It destroys mental power and memory, it blotches the complexion, dulls the eye, takes away the strength, and may even cause insanity. It is a habit most difficult to overcome, and may not only last for years, but in its tendency be transmitted to one’s children.

Touching the enemy

All of this excitement proved baseless. Masturbation now seems, at least to the educated, to be the quintessential victimless crime. At least when practised alone or among consenting adults. And as long as the method of fantasy doesn’t impinge on anybody else’s rights. Yet the subject still cleaves opinion in contemporary educated societies.

Consider the recent cringe-worthy campaign by Brigham Young University – Idaho that considered modern masturbation and porn use patterns alarming enough to erect a turgid war metaphor. The masturbators are personified by spent soldiers, left dying (and, it seems, tugging) on the battlefield by their fellows. Which of course invites the question of what the soldiers are masturbating against in this so-called “Great War”?

Last May, Hugo Schwyzer made a very interesting proposal in The Atlantic of the controversy that still inheres to self-pleasure.

Tell me how you really feel about masturbation, and I can more or less predict how you’ll feel about the more frequently debated “sex war” issues.

His point was that all the issues at stake in the “sex wars”, by which I would include the ideological tussles over abortion, contraception, promiscuity, sexual autonomy, sex education, mens’ and womens’ work and roles, homosexuality, gay marriage and even the importance of gender, are polarised on the question of what sex is for. If you believe sex is exclusively about connecting intimately with one other person and, thereby, producing children, then you will tend to take the conservative positions on these issues. You will also tend to view masturbation as wrong, wasteful or even sinful.

On the other hand, “delighting in something that, first and foremost, belongs to us as individuals” tends to be associated with more progressive attitudes about all of these issues. And what purer expression of sex belonging to individuals can be found than the art of self-pleasure?

Who wins, who loses?

Where does this tension about what sex is for come from?

Much resistance to masturbation turns on the perception that it represents a theft, robbing those who take matters in hand of their own health, vitality or ambition, or of taking something essential from the partner and the family unit. Some of the shame and stigma attached to masturbation in contemporary society prods at an inadequacy. Calling someone a wanker implies that whatever they are doing, that isn’t the way proper grown-ups roll.

Is masturbation only for losers, the terminally unattractive, and those stuck in sexless relationships? A large study of masturbation behaviour in the US suggests the reality is far more complex. For some, masturbation “compensated for a lack of partnered sex or satisfaction in sex” while for others it “complemented an active and pleasurable sex life”.

The fact that the most sexually satisfied subjects were also most directly in touch with their bodies supports the positions taken by Jocelyn Elders, and others who advocate masturbation is part of normal human sexuality. Masturbation is also most prevalent among the highly educated, and those not in conservative religious groups. That is to say those least likely to be swayed by supernatural or secular authority.

The narrow conception that sex is for procreation and the satisfaction of life-long spouses has served religions, monarchs and political leaders at various times. For one thing, it restricted the supply of sex. As I recently wrote, conservatives aren’t too keen on an over-supply of sex because that lowers the price – how hard men have to work to have (proper, married) sex. Mark Regnerus, in-house sociologist at the conservative Austin Institute, warns: “Don’t forget your Freud: civilisation is built on blocked, redirected, and channelled sexual impulse, because men will work for sex.” But to whose ultimate benefit that work goes remains opaque.

The societal changes associated first with the enlightenment, then with first-wave feminism and, eventually, the sexual revolution, concerned the elevation of the individual, and the capacity for men, and especially women, to own themselves. If people are not the property of a deity, a religious institution, or even a spouse, then they are not bound by the narrow conceptions of sexuality that suit the interests of those other “owners”.

This line of thought may provide one reason why the enlightenment, early feminism and the sexual revolution caused both new, more progressive attitudes to sex and strong backlashes – led by the likes of Tissot, Graham, Kellogg and BYU-Idaho – against those new attitudes.

Have a good month appreciating self-ownership in your own chosen way.

.

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Rob Brooks does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

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A complex cocktail: alcohol, sex and cute monogamous mammals

Influencing the drinking patterns of others. Apart from being in a short, overly fussy glass and sporting a slice of lemon rather than a lime, the good thing about these gins and tonics is they were made by somebody else. And so I’m not complaining. Source: cyclonebill/Flickr
Influencing the drinking patterns of others. Apart from being in a short, overly fussy glass and sporting a slice of lemon rather than a lime, the good thing about these gins and tonics is they were made by somebody else. And so I’m not complaining.
Source: cyclonebill/Flickr

How does alcohol consumption affect romantic life? Let me count the ways.

If popular advertising is to be believed, the consumption of high-end spirits almost guarantees a steady variety of glamorous amour. I was always surprised that James Bond – before Daniel Craig – opted to take his vodka martinis shaken rather than stirred. Bond was never short of anyone to stir his martinis.

From Dutch courage to a shared glass of champers to drunken would-rather-never-remember sex, alcohol’s tendency to reduce our inhibitions has changed the way drinkers meet and mate. But drinking is also a cause and a consequence of relationship breakdowns and considerable associated misery.

Which is why I’m fascinated to see how the world’s media covers a paper out today in the Proceedings of the National Academy of Science of the US (PNAS). It has an irresistible combination of clickbait-ready elements: a cute small mammal, booze and serious questions about monogamy.

The first element, the cute mammal, is the prairie vole, poster-child for wishful thinking anthropomorphising about monogamy and the power of love. Male-female pairs form long-lasting bonds, sleeping together, grooming one another and raising pups together.

The prairie vole looks even more virtuous alongside its shadier close relative, the montane vole, which tends to mate promiscuously and form no such pair bonds. Which means comparisons of the two species, from ecology to the molecular biology of receptors on the brain, can help resolve the mechanisms involved in prairie vole monogamy.

Early work on these species implicated the hormones vasopressin and oxytocin. Block their release in prairie voles, and they come over all promiscuous – just like montane voles. And it turns out the reward centres of prairie vole brains bustle with receptors for these hormones, but montane vole brains don’t. Decades of work on these closely related vole species have resolved, in considerable detail, the brain regions, receptors and molecules involved in regulating prairie voles’ much-admired mostly monogamous ways. Last June even saw the 21st century’s dark magic – epigenetics – implicated in understanding the neuroscience of how prairie voles “fall in love”.

But like so many mythologised monogamous relationships, a dark secret stalks the prairie vole love story. Because the vole has a bit of a drinking problem.

Not only do voles “self-administer” in much the same way that I do when I mix a gin and tonic, they can also “influence the drinking patterns of a social partner” in exactly the same way I do when I make one for a friend or beloved. But instead of the taste sensation of Hendricks, tonic and a quarter lime, the little fuzzies opt for a 1:10 mix of ethanol and water. They prefer it to plain water.

With an eye for a compelling study, Allison M.J. Anacker and colleagues saw an opportunity to study how self-administered alcohol consumption affects social bonding and the neural mechanisms by which prairie voles form monogamous couples. The effects of alcohol, it turns out, differed between female and male prairie voles.

Huddling up together is a reliable predictor that a couple of voles are likely to mate. Male voles that drank alcohol during a period of cohabitation were as likely to huddle up with a strange female as with a sexually receptive partner. Males who drank only water strongly preferred the partner animal over a strange female. Alcohol, it seems, disrupted the males’ tendency to behave like monogamous paragons of pair-bonded virtue.

Female voles that had been drinking alcohol, on the other hand, grew slightly more likely to huddle up to their partner and not a strange male. It seems that alcohol might enhance female pair-bonding at the same time as diminishing the male commitment to pair-bonding.

Detailed study of the voles’ behaviour as well as, eventually, their brains, revealed that alcohol directly affected the brain structures responsible for pair bonding rather than exerting indirect effects by causing drowsiness or altering levels of aggression. Alcohol, drunk during cohabitation with a potential mate, seems to affect male and female brains and behaviour differently.

Of course humans aren’t voles. Deciding how much to infer about human behaviour from a study on some other organism always presents a tricky challenge. It would be far too much to infer that drinking influences human pair-bonding in exactly the same way as it does for voles. But it would be ignorant to imagine that voles can teach us nothing of value here.

Insights from voles have already led to intriguing findings about the roles of vasopressin, oxytocin and their receptors in human commitment to their romantic partners and families. Men with a particular form of the vasopressin receptor gene, for example, exhibit a suite of traits that suggest they don’t form the same deep pair bonds that other men form: they make less committed partners, suffer from more marriage problems, are more likely to be unfaithful mates and, as a result, their relationships don’t last as long.

Alcohol inhabits a prominent yet complex place in the social and sexual lives of many adults. It can enhance bonding, ease courtship and foster closeness. And it can both moderate and cause stress, dominance/control issues and violence. The issues surrounding alcohol are so important, and so pervasive, that they should not be oversimplified or narrowly construed.

For me the most interesting thing about the vole study is the sex-specific way in which alcohol influenced pair bonding and behaviour. The study of sex differences in brain anatomy and function is an area replete with controversy and contesting ideological claims. Here is an area in which the study of sex differences can transcend simplistic ideological bickering about sexism and gender-free wishful thinking. Surely understanding the ways in which environments, genes and brains interact – over questions as socially pressing and consequential as alcohol and family function – could potentially be harnessed to great effect.

Rob Brooks does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

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Can monogamy undermine intelligence?

Yes

At least over 100 generations in Drosophila melanogaster vinegar flies.

“Male cognitive performance declines in the absence of sexual selection” proclaim Brian Hollis and Tadeusz Kawecki in the title of a paper out this week in Proceedings of the Royal Society of London B.

It’s the kind of experiment I love to see done – in somebody else’s lab. Set up some populations (lines) of a fast-breeding animal. Let some lines compete for mates but impose strict life-long monogamy on the other lines. Repeat. Then, a couple of years down the line, if all goes well, measure various traits you predict will be affected by the presence (competition) or absence (monogamy) of sexual selection.

Normally, monogamous lines end up more productive. When there is no advantage to males of jostling for dominance over one another or competing frantically for female attention, the fittest males are usually those that stay alive and don’t harm the females. But in lines where males have to compete with one another, females often end up collateral damage of the robust competition between males and even the chemical warfare between their ejaculates.

But this particular paper looked at male smarts.

Put a male vinegar fly into a vial with one receptive and a few non-receptive females, and he will court them all. How quickly he realises which female he should be courting can be used as a measure of his mating savvy.

No surprises that this measure of smarts declined after 100 generations of enforced monogamy. Each monogamous line male comes from a long line of male flies who never had to decide which female to court.

But it turns out that males from monogamous lines were also much slower to learn to associate a particular smell with the likelihood of their vial being shaken (a nasty thing for a fly to endure). So, it seems there’s some kind of general decline in cognitive performance in those lines where monogamy has been enforced for 100 generations.

Sexual selection for smarts

It’s a pretty neat finding from a purely genetic and evolutionary point of view. That removing the normally hectic competition among males (by enforcing monogamy) to find, court and sometimes coerce female flies leads to the whithering of cognitive performance reveals the role of sexual competition and mate choice in the evolution of cognitive capacity.

Of course the Drosophila study says very little directly about human intelligence. It’s value – apart from the discipline-specific genetic issues it addresses – is the clean experimental evidence it provides that sexual selection can favour the evolution of cognitive performance.

But this evidence cannot help but stir human curiosity. To what extent do we owe our much-celebrated human intelligence to sexual selection?

In The Mating Mind, evolutionary psychologist Geoffrey Miller made the intriguing case that we owe much of human intelligence to the never-ending competition to out-compete our rivals in love and to find, court, keep and even manipulate potential mates. In the past decade or so, support for Miller’s hypothesis has accumulated from a variety of sources.

Does this mean we’re getting dumber?

Ever since Darwin gave us a viable process – natural selection – by which evolution occurs, some thinkers have fretted about whether people are getting dumber. In 2012 I wrote about one such argument in which Stanford geneticist Gerald R. Crabtree lamented that humanity is “almost certainly” losing its superior intellectual and emotional capacities.

Such worries seem to come from a misplaced nostalgia about the purifying nature of natural selection in the past. The idea that back-in-the-day, those of below average intelligence fell victim to lions, wolves or starvation. But modern human institutions, by mollycoddling the intellectually weak, are somehow undermining our collective genetic intelligence.

It’s the kind of argument one might expect to find in a 21st Century tabloid lamenting the rise of the welfare state. But it’s not too far from Plato either.

Coming from exactly this position, Herbert Spencer mangled Darwin’s idea of natural selection into the pithy but hopelessly wrong notion of “survival of the fittest”. When Spencer co-opted natural selection to substantiate laissez-faire capitalism and oppose the “poor laws”, he diminished evolutionary thinking in a way that it has never quite shaken.

Likewise, Francis Galton drew on the work of his cousin – Charles Darwin – to argue that governments protecting the weak and infirm thwart natural selection’s role in improving humanity. In so doing he gave us several important statistical concepts, including correlation, regression to the mean. And he extended it to suggestions for action that initiated modern eugenics, another shameful perversion of evolutionary thinking.

The idea that human intelligence is on a slippery evolutionary slope lubricated by the protections societies provide to their less fortunate or well-endowed citizens has always been a dangerous one. But while Spencerian survival of the fittest doesn’t hold as much cachet as it once did, I am still often asked by well-meaning readers whether an apparent decoupling between intelligence and reproduction is leading us up the evolutionary garden path.

The questioners seem propelled by the same intuition that had people giggling at the band Harvey Danger’s 1997 observation that “only stupid people are breeding”. It’s an impulse that fuels much of the prurient interest in and sneering about shows like Maury or Jersey Shore.

Harvey Danger’s Flagpole Sitta. Relevance? 0:57.

It would be impossible to replicate the Drosophila experiment in humans. Randomly assigning individuals to life-long total monogamy for generation after generation is a fate, once you think of it, far worse than it even sounds. Hopefully the mistakes governments made with eugenics have taken half-baked social engineering programs of this nature off the table.

Modern civilisation has – thank goodness – eliminated many of the ghastly ways in which our ancestors could die. And that has dampened natural selection on survival. But sexual selection is always happening. And much of sexual selection’s power comes from the fact that humans aren’t life-long exclusive monogamists.

People compete for status and wealth with which to attract mates, they do the most outlandish things to get noticed and they engage in the most elaborate forms of persuasion to court and seduce their mates. Either to find somebody to settle down with, or to find another, or another. These are all expressions of intelligence, and while smarts don’t always win out, they usually help.

In fact, Mark Roeder, in his new book Unnatural Selection: Why the Geeks Will Inherit the Earth, argues that the anthropocene has seen intelligence eclipse strength vigour as determinants of success. If that is the case, then sexual selection may well ensure that 100 generations – say 2,500 years – from now, humans will have evolved to be much, much smarter than they are today.

Rob Brooks does not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.

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