Keith E Rice's Integrated SocioPsychology Blog & Pages

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Is Sexual Infidelity Inevitable?

Updated: 20 November 2018

Personal sexual fidelity is certainly something many people truly espouse as a noble intention at certain points in their relationships – such as when first falling in love, or getting married, the woman getting pregnant or possibly resolving their partner’s bouts of insecurity. Some people seem genuinely to espouse fidelity to each other for years and sometimes even lifetimes.

But these days actually sticking to one partner seems to be a real problem for an awful lot of people.

In the Western world people – particularly in the professional/middle classes – tend to ‘settle down’ later (in their thirties, often with a number of ‘notches on the bedpost’). Fewer couples marry. (Marriage in itself cannot be a guarantee of permanence or fidelity; but, in theory, it is an action of intent.) People with money who do marry often make prenuptial agreements, effectively planning for the end of their relationship. Although there has been a noticeable decrease in UK divorce rates of 4.9% since 2016, the number of marriages ending in divorce in 2017 was still high at 42%. The number one reason cited for divorce remains adultery – although a number of marriages do manage to survive at least one and occasionally several infidelities.

Margo Stilley and Keiran O’Brien having penetrative sex in ‘9 Songs’

Meanwhile promiscuity and infidelity fill our modern entertainment media – often the narrative centrepiece in film, television and theatre dramas. Nudity and explicit simulated sex acts have featured strongly in TV dramas like Game Of Thrones, Masters Of Sex and Spartacus. Even some recent mainstream movies – eg: 9 Songs (2004) and Love (2015) – have featured explicit and completely uncensored scenes of actors having real sex. Many pop songs feature suggestive and sometimes explicit lyrics – with promotional videos to match. And we have become fascinated with celebrity sex lives. For example, celebrity-oriented magazines like Heat and Now are actually circulation-dependent on reporting the who’s-shagging-who this week syndrome.  A number of celebrities – starting with Pamela Anderson in 1995 and including the likes of Paris Hilton and Kim Kardashian – have had ‘home porn’ movies ‘leaked’ (sold) to porn websites.

In the early 1960s Liz Taylor adding yet another divorce and yet another husband to the list was seen as somehow sad or bizarre. Now our 21st Century media glories in celebrity romance, infidelity and bust-up. In Summer 2004 then-England football team coach Sven Goran Eriksson was exposed as cheating on his long-time partner, Nancy Dell’Olio. Nancy wasn’t just long-time, she was long-suffering – since just over a year previous Sven had been caught having an affair with television presenter Ulrika Johnson. The fact that Sven’s sperm receptacle this time, Faria Alam,was also obliging Sven’s boss, Mark Palios, Chief Executive of the Football Association, doesn’t seem to have caused much of a stir other than adding a quite delightful frisson to the whole affair for the tabloids. The promiscuity that would have caused real outrage back in the early 1960s seems merely to add spice and voyeuristic excitement.

Of course, the fascination with sex is older than Homo Sapiens and a prurient fascination with famous or powerful people having sex – particularly with people they nominally aren’t meant to! – probably dates back to the earliest civilisations. However, there does seem to have been quite a cultural shift in Western society during the second half of the 20th Century and into the 21st.

Not only is our media glamorising celebrity promiscuity; but there seems to be a trend to normalise promiscuity as a way of life. For example, Channel 4 and Channel 5, having successfully broadcast pseudo-documentaries on the ‘sex industry’ for several years before, turned its attention in the Noughties to making television programmes about apparently ‘normal’ everyday people having group sex and indulging in wife swapping. The ongoing popularity of such programmes – and the money they generate for the programme makers – is indicative of just how much our society has been infected with glamourised sex and promiscuity memes.

From the Gravesian perspective, there is no doubt the RED vMEME will indulge in all this salaciousness and thoroughly enjoy it – and the ORANGE vMEME will continue to push it as a major money maker. But, when these memes are so prevalent, is it any wonder being loyal to one partner for years can so easily become an issue?

To understand this phenomenon, we need to explore the underlying motivations driving human interactions at several levels.

So the first question we have to work on is…

Is monogamy normal for humans or is promiscuity inevitable?
Let’s define our terms for mating systems here:-
○ Monogamy: one man, one woman
○ Polygyny: one man, more than one woman
○ Polyandry: one woman, more than one man
○ Promiscuity: any man can go with one or more women; any woman can go with one or more men

Pre-Western dominance mating systems. Graphic copyright © 1984 Academic Press

Historically polygyny was by far the main pre-Western hegemony/non-Christian mating system. As enshrined in religious doctrines such as those of Shia Islam, one man, who can afford it, supports several women with whom he has sex and, as a consequence, children. This may not go down well with the advocates of one man/one woman romantic love as a basis for marriage; but it has provided a stable mating system for centuries in many cultures.

From the point of view of Evolutionary Psychology – in which the genetic motif is seen as adaptation-to-survive-and-reproduce – this is a highly-successful adaptive strategy for procreation. The man gets to spread his genes through several women – rather than just one, as monogamy would demand. That gives greater chance of his genes being passed down to the next generation. For the women, they get the benefit of being taken care of by a male with good resources which will enable more effective nurturing for their offspring – thus increasing the woman’s chances of passing on her genes.

This is all down to the size of the individual sex’s gametes (sex cells). Since men produce sperm in millions, it makes sense as an adaptive behaviour to impregnate as many women as reasonably possible. Since women produce a limited number of eggs, each one impregnated needs to be given maximum care, to maximise its chances of survival and then reproducing its genes again as an adult man or woman.

In the Gravesian approach, this is a function of the BEIGE vMEME – working at the Survival level in Abraham Maslow’s (1943) Hierarchy of Needs. Pre- or non-cognitive survival behaviours – including behaviours to maximise the chances of reproducing one’s genes – are natural at this level. So males being promiscuous can be considered a natural behaviour at this level.

Charles Darwin (1871), in whose work Evolutionary Psychology is rooted, believed that male promiscuity was an inevitable (if not always desirable) adaptive trait while females were naturally monogamous as long as the male was protecting and providing for her and her offspring.

However, over the past 30-40 years, a newer train of thought has emerged in Evolutionary Psychology – that it is adaptive for the female also to be promiscuous in certain circumstances. This is to do with the woman’s hunt for the best genes with which to reproduce. Thus, a furtive one night stand with a ‘hunk’ with better genes than the woman’s husband (or committed partner) can be considered adaptive behaviour if the woman succeeds in getting pregnant by the hunk and hoodwinks the husband/partner into believing the child is his and thus providing and caring for it.

Evidence for this comes from linking 2 key pieces of work. From a sample of 103 women in their mid-30s, Jacky Boivin et al (1998)  demonstrated that the more intense a woman’s orgasm, the more of her partner’s sperm is retained. The women rated their enjoyment of the sex and this was correlated with the amount of sperm in a sample of the women’s cervical mucus collected within 3 hours of having sex. (The tip of the cervix will dip down into the ejaculated sperm during orgasm and effectively propel the sperm into the uterus.) Add to this Robin Baker & Mark Bellis’ (1995) finding that a woman is more likely to orgasm with an irregular partner than a regular one, thus increasing her chances of conception – and it would seem it could indeed be an adaptive behaviour for woman to have sex with a non-regular partner if she wants to get pregnant.

According to whose statistics you believe, the named father on the birth certificate of between 10% and 30% of British children is not actually the biological father. One of the earliest pieces of research into this phenomenon was by E E Philipp (1973). His research involved taking blood samples from a group of men, women and children in the south-east of England. To his surprise, he found that as many as 1 in 3 children could not possibly have been the offspring of their ‘official’ fathers. A similar level of erroneous paternity – 30% – was found amongst 2 tower block communities in different parts of England, according to Robin Baker & Elizabeth Oram (2000). Matt Ridley (1993) put forward a lower figure of 20% from his research.

Lynn Cherkas et al caused something of a stink in November 2004 when they claimed proof of a genetic link to infidelity. They had found a concordance rate of 44% infidelity between monozygotic/identical female twins compared to an average risk of only 22% in the general adult female population. Although they did not identify any particular gene as such, the researchers claimed that variations on between 50 and 100 genes associated with chromosomes 3, 7 and 20 could be responsible for female promiscuity.

So are women programmed for multiple partners? Helen Fisher (1998) states so. She argues that it is an adaptive strategy to have children by different fathers who will pass on different strengths and abilities. She cites 4 years as being around the time a relationship will last on this basis. After around 36 months the chemical drivers for the passion will be dying down. However, it may take the woman another 12 months or so to come to the conclusion that she is no longer ‘in love’ and, therefore, be ready to move on. Fisher does concede that many relationships do not end like this because the partners develop bonds of affection which make them want to stay together. However, she makes it clear this is a different ‘love’ – companionate love – to the first rushes of passion which produce intense sexual activity.

Cherkas et al’s 44% concordance rate is high but far from conclusive. If it were to be argued that women have an automatic natural biological driver towards promiscuous sex, then statistically the concordance rate would have to be at least 80%.

Perhaps the best way of making sense of Cherkas et al’s findings and Fisher’s proposition is to take the Diathesis-Stress view. Yes, it may be that there is a significant number of women with a genetic predisposition to multiple partners but it needs a stress or lifestyle trigger for it to be realised.

The second question we need to work on is…

Do we need to love and to be loved?
Where the Evolutionary approach starts to show holes, is that it doesn’t account for the idealisation of ‘romantic love’ even in pre-Western hegemony/non-Christian societies. So men with harems still fall in love with a stranger and cheat on their wives sometimes; and women, who would stand much better chances of passing their genes on successfully with a rich man, fall in love with beggars.

The notion of ‘romantic love’ is one of the most powerful memes ever to have materialised in human civilisation. As much as, if not more than, sex-for-sex’ sake, love is sold as a desirable commodity in our consumer society. For every hit single extolling the virtues of sex, there are ten dealing with the ups and downs of love. And while we slaver salaciously over the latest celebrity scandal, the magazine editors know that a celebrity love affair at its peak is even more popular. Happy Charles & Diana sold more than divorcing Charles & Diana – and still do! Even happy Charles & Camilla outsell divorcing Charles & Diana. As for Charles’ 2 sons, the media delight in photo ops of the princes and their apparently very successful marriages.

Happy: Prince Charles, wife, sons and their wives and Charles’ grandchildren. Copyright © 2018 Getty Images/Chris Jackson

And, whether it’s wide-eyed innocent teenagers plighting their troth at the altar or a middle-aged couple who’ve each been around the block a few times, most observers tend to nurture the hope that it will work for them.

Historically sex as a meme has been repressed at times – eg: in the Victorian era. Love rarely, if ever, has been repressed. Even in arranged marriages, it is usually hoped that the couple will find romantic love. Which of these two memes is the most powerful? While it might be close at times, it does appear that romantic love is the more powerful ‘mind virus’.

What we are talking about is an extreme manifestation of the need to affiliate – Maslow’s level of Belonging. In the Gravesian approach, the PURPLE level effectively collapses Maslows’s Safety and Belonging levels into one in which people find safety by belonging. And nobody belongs to each other more than a couple in the throes of romantic love! (Such feelings of belonging have been expressed at times as being so intense the couple want to meld into each other!)

Of course, where human beings are concerned, things are often more complex than many psychological theories allow. A complete disassociation between romantic love and sex as I have described it above is both impossible and potentially dangerous. (Although it has been tried by societies – as in the aforementioned Victorian era!)

Most couples, in the throes of romantic love, will have a lot of sex. After a bout of mutually-satisfying sex, they usually find their feelings of affection and belonging with their partner considerably enhanced.

Sociobiology – so often claimed as a close ally by the Evolutionary camp – offers an explanation of this phenomenon. Humans in the throes of great sexual arousal and orgasm experience high levels of the hormones vasopressin and oxytocin. A study by Sue Carter & Lowell Getz (1993) into the unusually monogamous relationships of American prairie voles found high levels of vasopressin and oxytocin associated with the animals’ bonding patterns. While there is still research to be done in this area, studies such as that of  Thomas Insel et al (1998) have built on Carter & Getz’ work to associate sex in humans producing oxytocin and vasopressin with the bonding effect ‘good sex’ has.So it does appear that we are programmed for the act of sex to make us want to belong to belong to our sexual partner. So we have on one hand a driver to reproduce our genes and on the other hand a need to affiliate, with it seems a biological driver to affiliate intensely with the person with whom we seek to pass on our genes.


It’s perhaps worth considering here Susan Blackmore’s (1999) position that memes can – and often do – drive genetic adaptation.

In tune with the mind-blowing possibilities that hypothesis opens up, the third question we need to work on is…