This is an exceptional opportunity at UNSW Sydney for students interested in how evolved traits interact with economic circumstances to shape behaviour in contemporary societies.
Students may be trained in evolutionary biology, psychology, anthropology, economics or other disciplines.
This position is supported by the generous Scientia PhD Scholarship Scheme at UNSW Sydney, Australia. In addition to a stipend of $40K p.a. There is a $10k p.a. Travel allowance, and other opportunities for career development.
We propose to test the exciting idea that economic inequality among households also shapes mating competition, giving rise to many of the stark sex differences in dress, spending patterns, and mental and physical health that pervade societies. While wealthy Western countries have progressed steadily toward gender-equitable opportunities over the last century, differences between women and men in aggression, interests and the incidence of diseases like anxiety and depression have, paradoxically, increased. It is clear that ossified old ways of understanding gendered traits as either biologically essential o
r socially constructed have little to offer in terms of further understanding.
Our approach transcends old territorial boundaries, and promises a newer, better and more general way to understand gendered behaviours, including those implicated in harm to mental health, safety, and happiness. The work will involve both experimental psychological research and analysis of economic data. The project will be designed in collaboration between student and supervisors.
There may be opportunities for field work in Australia or the Pacific islands.
This is a highly competitive scheme, with excellent support, open to students from any country.
At the same time as you fill out the form, please email rob.brooks – at – unsw.edu.au a CV, academic transcript, and a few paragraphs on why you are interested int his project, plus any questions you have for us.
Up to 2 students will be asked to submit full applications in August.
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.
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.
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.
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.
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:
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”.
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.
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.
Rob Brooks is Scientia Professor of Evolutionary Ecology; Director, Evolution & Ecology Research Centre at UNSW Australia
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.
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.
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.
Rob Brooks is Scientia Professor of Evolutionary Ecology; Director, Evolution & Ecology Research Centre at UNSW Australia
Many scholars of Renaissance art tell us that Botticelli’s Birth of Venus captures the tension between the celestial perfection of divine beauty and its flawed earthly manifestation. As classical ideas blossomed anew in 15th-century Florence, Botticelli could not have missed the popular Neoplatonic notion that contemplating earthly beauty teaches us about the divine.
Evolutionary biologists aren’t all that Neoplatonic. Like most scientists, we’ve long stopped contemplating the celestial, having – to appropriate Laplace’s immortal words to Napoleon – “no need of that hypothesis”. It is the messy imperfection of the real world that interests us on its own terms.
My own speciality concerns the messy conflicts that inhere to love, sex and beauty. Attempts to cultivate a simple understanding of beauty – one that can fill a 200-word magazine ad promoting age-reversing snake oil, for example – tend to consistently come up short.
Waist to hip
Nowhere does the barren distinction between biology and culture grow more physically obvious than in the discussion of women’s body shapes and attractiveness. The biological study of body shape has, for two decades, been preoccupied with the ratio of waist to hip circumference.
With clever experimental manipulations of line drawings, Devendra Singh famously demonstrated that images of women with waists 70% as big as their hips tend to be most attractive. This 0.7:1 waist-to-hip ratio (WHR), it turns out, also reflects a distribution of abdominal fat associated with good health and fertility.
Singh also showed that Miss America pageant winners and Playboy playmates tended to have a WHR of 0.7 despite changes in the general slenderness of these two samples of women thought to embody American beauty ideals.
Singh’s experiments were repeated in a variety of countries and societies that differ in both average body shape and apparent ideals. The results weren’t unanimous, but a waist-to-hip ratio of 0.7 came up as most attractive more often than not. The idea of an optimal ratio is so appealing in its simplicity that it became a staple factoid for magazines such as Cosmo.
There’s plenty to argue about with waist-hip ratio research. Some researchers have found that other indices, like Body Mass Index (BMI) explain body attractiveness more effectively.
But others reject the reductionism of measures like WHR and BMI altogether. This rejection reaches its extremes in the notion that ideas of body attractiveness are entirely culturally constructed and arbitrary. Or, more sinisterly, designed by our capitalist overlords in the diet industry to be inherently unattainable.
The evidence? The observation that women’s bodies differ, on average, between places or times. That’s the idea animating the following video, long on production values, short on scholarship and truly astronomic on the number of hits (21 million-plus at the time of writing):
This rather questionable video, called ‘Women’s Ideal Body Types Throughout History’, is getting a lot of airplay on YouTube.
I note that Botticelli’s Venus looks more at home in the 20th Century than among the more full-figured Renaissance “ideals”. So do the Goddesses and Graces in La Primavera. Perhaps there was room for more than one kind of attractive body in the Florentine Renaissance? Or is the relationship between attractiveness and body shape less changeable and more variegated than videos like the one above would have us believe?
Not that I’m down on body shape diversity. Despite the fact that there seems to be only one way to make a supermodel, real women differ dramatically and quite different body types can be equally attractive. The science of attractiveness must grapple with variation, both within societies and among cultures.
Enter the BodyLab
For some years our research group has wrestled with exactly these issues, and with the fact that bodies vary in so many more dimensions than just their waists and their hips. To that end, we established the BodyLab project, a “digital ecosystem” in which people from all over the internet rate the attractiveness of curious-looking bodies like the male example below.
We call it a “digital ecosystem” not to maximise pretentiousness, but because this experiment involved multiple generations of selection and evolution. We started with measurements of 20 American women, a sample representing a wide variety of body shapes.
We then “mutated” those measures, adding or subtracting small amounts of random variation to each of 24 traits. Taking these newly mutated measures we built digital bodies, giving them an attractive middle-grey skin tone in an attempt to keep variation in skin colour, texture etc out of the already complex story.
If you want to help out with our second study, on male bodies, visit BodyLab and click through to Body Shape Study and then Rate Males (Generation 6).
This all involved considerable technologic innovation, resulting in an experiment unlike any other. We had a population of bodies (120 per generation) that we could select after a few thousand people had rated them for attractiveness. We then “bred” from the most attractive half of all models and released the new generation into the digital ecosystem.
What did we find? In a paper just published at Evolution & Human Behavior, the most dramatic result was that the average model became more slender with each generation. Almost every measure of girth decreased dramatically, whereas legs and arms evolved to be longer.
That may not seem surprising, particularly because the families “bred” from the most overweight individuals at the start of the experiment were eliminated in the first few generations.
But, after that, more families remained in the digital ecosystem, surviving generation after generation of selection, than we would have expected if there was a single most attractive body type. The Darwinian process we imposed on our bodies had started acting on the mutations we added during the breeding process.
More meaningful than the mean
Those “mutations” that we introduced allowed bodies to evolve free from all the developmental constraints that apply to real-world bodies. For example, leg lengths could evolve independently of arm lengths. Waists could get smaller even as thighs got bigger.
When we examined those five families that lasted longest as our digital ecosystem evolved, we observed a couple of interesting nuances.
First, selection targeted waist size itself, rather than waist-hip ratio. No statistical model involving hip size (either on its own or in waist-hip ratio) could come close to explaining attractiveness as well as waist size alone. Our subjects liked the look of slender models with especially slender waists. There was nothing magical about a 0.7 waist-to-hip ratio.
Second, within attractive families, which were the more slender families to begin with, evolution bucked the population-wide trend. These bodies began evolving to be more shapely, with bigger busts and more substantial curves.
It turns out there’s more than one way to make an attractive body, and those different body types evolve to be well-integrated. That’s a liberating message for most of us: evolutionary biology has more to offer our understanding of diversity than the idea that only one “most attractive” body (or face, or personality) always wins out.
What about the cultural constructionists? Are body ideals arbitrary, or tools of the patriarchal-commercial complex?
Our results suggest that the similarities between places, and even between male and female raters, are pretty strong: the 60,000 or so people who viewed and rated our images held broadly similar ideas of what was hot and what was not. But their tastes weren’t uniform. We think most individuals could see beauty in variety, if not in the full scope of diversity on offer.
What’s cool about our evolving bodies, however, is that we can run the experiment again and again. We can do so with different groups of subjects, or even using the same subjects before and after they’ve experienced some kind of intervention (perhaps body-image consciousness-raising?). I’m hoping we can use them to look, in unprecedented depth, at the intricate ways in which experience, culture and biology interact.
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’.
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):
With how many different partners have you had sex within the past 12 months?
With how many different partners have you had sexual intercourse on one and only one occasion?
With how many different partners have you had sexual intercourse without having an interest in a long-term committed relationship with this person?
Sex without love is OK. (this and the next two questions answered on a scale from strongly disagree to strongly agree)
I can imagine myself being comfortable and enjoying “casual” sex with different partners.
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.
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).
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
“Heredity”, opined the pioneering cultural anthropologist Alfred L. Kroeber in 1915, “cannot be allowed to have acted any part in history”. I have yet to encounter a crisper expression of the view that biological explanations have no place in the study of society and history. Kroeber’s words have resonated through the social sciences for a century, divorcing nurture from nature, social from biological, at considerable harm to our understanding of society and what it means to be human.
Fortunately, many 21st Century anthropologists, economists, neuroscientists, geneticists, sociologists and thinkers so busily inter-disciplinary that they defy dusty departmental labels, are consigning the hoary distinction between nature and nurture to the past. Likewise the distinction between heredity and history is steadily dissolving as the where intimate links between evolutionary fitness and major historic transitions come into view.
Last week’s European Journal of Human Genetics, for example, carried a fascinating article led by evolutionary geneticist Patricia Balaresque exploring the signature of historic population expansions in the distribution of Y-chromosome genotypes of men alive today.
The Y of who, what and when
The the human Y chromosome represents a tiny portion of the genome, including the genes that trigger a foetus to develop into a male, rather than following the default female pathway. Every now and then a small change occurs in one of the less important parts of a Y-chromosome’s DNA. Such a change is passed to a man’s sons, those sons’ sons, and so on. That means there’s quite a bit of variation in these Y-chromosome sequences in any human population.
So if a man happens to have many sons, who each go on to have many sons and so on, one might detect a sudden surge in the frequency of the Y-chromosome sequence borne by that line of men (patriline). In 2003, a large team from Oxford University detected evidence of just such an event. Across much of Asia, one particular Y-chromosome sequence was carried by 8 percent of all men. In a paper pithily titled “The Genetic Legacy of the Mongols”, they famously fingered Genghis Khan as the chief suspect.
The pattern of variation within the lineage suggested that it originated in Mongolia approximately 1,000 years ago. Such a rapid spread cannot have occurred by chance; it must have been a result of selection. The lineage is carried by likely male-line descendants of Genghis Khan, and we therefore propose that it has spread by a novel form of social selection resulting from their behavior.
Where by ‘behaviour’ they mean more than the Great Khan’s triumph in unifying the Mongols and establishing the largest continuous empire history has ever known. For Khan was as much about the establishment of a genetic dynasty as a political one. According to one disputed quote, he once said:
The greatest joy for a man is to defeat his enemies, to drive them before him, to take from them all they possess, to see those they love in tears, to ride their horses, and to hold their wives and daughters in his arms.
Or words to that effect.
Such a genetic legacy is far more than the work of a single man. It is likely that Khan’s uncles, brothers and cousins, played a substantial role, too. And his direct male descendants spread both his empire and his genetic legacy. Ghenghis’ grandson, Kublai Khan, married four main Empresses, but, according to Marco Polo’s Travels was attended to by hundreds of beautiful young women, working five at a time in three-day shifts. And a much greater number of women, recruited to the palace but, after a second round of screening, not deemed perfect enough for the Khan himself, were bestowed on Kublai’s nobles, many of whom would have been relatives sharing his patriline and Y-chromosome.
Khan not the only one
The Mongol expansion is far from the only such event to leave a genetic signature. A 2005 paper identified a particularly successful lineage that expanded about 500 years ago in Northeastern China, possibly through the lineage who established the Quing Dynasty.
Last week’s findings report on a survey of 5321 men from 127 Asian populations, testing for evidence of similar population expansions. Belaresque and her collaborators identified eleven such events, including the ones tied to the expansions of the Mongols and the Qing dynasty. And some of those events date back as far as 2100 BCE.
The earliest expansions, between 2100 and 300 BCE, are associated with the flourishing of agriculture in the Fertile Crescent, East India, and South East Asia. As agriculture took hold, elites accumulated wealth and influence beyond anything our hunter-gatherer ancestors could have conceived. These represent perfect conditions for sexual despots: male rulers who take many wives, keep numerous concubines or mistresses, and have many offspring. They also establish successions that favour their male descendants, handing them the wealth and power to become sexual despots themselves.
Another expansion began around 1100 CE in the Near East and expanded to the South East Indian coast. This might be a signature of the “rapid expansion of Muslim power … after the establishment of a unified polity in the Arabian peninsula by Muhammad in the 7th Century and under the subsequent Caliphates”.
The Mongol and Qing expansions, and another from Northeast China beginning no earlier than 850 CE, were not associated with the establishment and spread of agriculture, but rather with nomadic, pastoral lifestyles made possible by the domestication of horses. Pastoral nomads ruled the steppes for thousands of years, thanks to their horse-powered mobility and fighting ability.
They established several empires, giving rise to hierarchies, elites and patrilineal reproductive despots like the Khans and the Qing. And their Silk Road trade corridor facilitated westward expansion of their genetic dynasties.
Heredity and History
Even in the rather well-studied case of Genghis Khan we are well beyond certain idenfification of the individual progenitors whose success sparked each expansion. Innovative analyses and lucky ancient DNA finds may yet do so for some cases. But the ability to detect great tides of patrilineal descent in societies of various types offers far more interesting possibilities than compelling personal narrative.
The evidence shows that with great power and wealth can come great evolutionary fitness. The tools are now falling into place to assess how much the psychological adaptations that shape reproductive success have given history its shape.
This is one tale where History certainly represents HIS Story. The fact that new Y chromosome sequences can spread so fast and so wide when history’s tide turns suggests that a very small number of sexually despotic men can leave massive numbers of descendants. But each man who traces his descent back to Genghis Khan or another such super-ancestor through an unbroken male line has sisters who do so too, save for the very last branch in their family tree. If 2% of people in Asia descend on a male-only lineage from the same male ancestor as Khan, then how many times do they descend from him through at least one female ancesor?
Each of us descends many times over from a great many sexual despots. It would be Kroeber-like wilful ignorance to be think we don’t also inherit many of the genes that biased their behaviour toward the accumulation of power, the vanquishing of rivals and reproductive despotism.
And when I say “we”, I don’t only mean men. Every man has a mother. Every descendant of Ghenghis Khan is also a descendant of his mother Hoelun.
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:
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.
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.
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.
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.
The soccer World Cup (yes, I persist in calling it “soccer”) is the one time in every four years I pay any sustained attention to the round-ball game. There is so much to love about the world’s most popular sport, played by its best players, with fanatical but mostly benign national supporters.
And yet by tournaments’ end I cannot bear to watch another dive, any more theatrical writhing on the ground or another posse of 20-something millionaires heatedly admonishing an official. Perhaps it’s something in the water at my place or a consequence of being thrashed too frequently in high school, but I prefer the stoic deference to authority of rugby union, in which backchatting the referee automatically moves the penalty 10m closer to your goal line.
So, with all the bright-eyed hope in the world game, I rose this morning at six to watch Brazil’s inevitable dismantling of Croatia. But Croatia’s Portuguese interpreter clearly couldn’t understand the memo, written as it was in Português do Brasil. Unaware they were supposed to be dismantled, they had the temerity to go ahead in the 11th minute.
A cracking contest, then, made even when Neymar slipped one just inside the Croatian post in the 29th minute. Very little remonstrating, some robust challenges but not too much play-acting, and very few dives. Until the 71st minute.
This is why soccer players dive. “Scientifically proven” as they say in pseudoscientific advertisements for fast-moving consumer goods. In this case, Fred’s dive fits perfectly with a scientific analysis of soccer diving by Gwendolyn David in 2011 and a team of collaborators at the University of Queensland.
In order to understand the dynamics of who dives and when, David viewed 2,800 falls in 60 matches of soccer across 10 professional leagues. David’s PhD supervisor and collaborator on the paper, Robbie Wilson, and Amanda Niehaus wrote about the paper’s findings and implications for The Conversation when the paper was published. As they put it:
It turns out that diving is more common when there’s more to gain by it: in the offensive half of the field – specifically, in or near the penalty box – and when scores between the teams are tied.
That’s exactly what happened this morning. Fred dived in a part of the field where he had everything to gain and almost nothing to lose. And it isn’t just Croatian supporters who thought the decision to award a penalty – the penalty that broke the tie – diminished an exciting game of football.
I’ll probably get up most mornings to watch the games, but I’d rather see referees take a harsher line on the theatrics. Like those zero-tolerance rugby referees, I’m pretty sure a few more yellow cards would tone down the histrionics and improve the overall spectacle. In fact David’s analysis shows that in leagues where refs are tough on diving, players do it less often.
My daughter was born the night John Aloisi scored that goal to put Australia through to compete in Germany 2006. And all Australian supporters know where that campaign ended up. Two words: Fabio Grosso.