A little-known study from 2007 suggests that, contrary to popular expectations, having higher testosterone levels may make a man more, not less, faithful to his partner.

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Does being high T make you more or less faithful? One study strongly suggests the former.

If you or I were to take a straw poll right now on whether high-testosterone men are more or less faithful than low testosterone men, it’s likely that most people would answer ‘less faithful’. After all, isn’t testosterone what makes men more bloke-y, and isn’t part of being a bloke chasing after anything with a pulse? Depending on who you asked, perhaps you’d even be given a little lecture on ‘toxic masculinity’, levels of which rise dangerously as men become more saturated with testosterone; perhaps even a man might say this to you.

Actually, the relationship between testosterone levels and behaviour isn’t quite as simple as we might be led to believe by NYT op-eds or the musings of Twitter talking-heads.

In recent months, as part of detailed series on testosterone, we’ve covered two studies on the master male hormone which reached a surprising conclusion: that higher levels may equate with increased levels of honesty. In another article we detailed how fitness inversely correlates with deviancy: the less fit you are, your likelihood to be a deviant increases.

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Testosterone and Faithfulness

We observed that the link between testosterone and ‘bad behaviour’ had actually been investigated in only the most superficial way, with little attention paid to untangling the complex interrelationships in a way that would allow causality to be established. We wrote:

‘While it is true that psychopaths have been shown to have higher testosterone levels, for instance, and increased testosterone has been linked to aggressive, risky behaviour and posturing, such studies rarely address the question of causality in a satisfying way. Is it the increased testosterone that is causing the psychopathy or not? Or is there some other mechanism at work?’

The two studies both went to great lengths to establish a causal relationship between testosterone and honesty. Exogenous testosterone gel was administered to a group of subjects and their moral behaviour was compared to that of subjects who had received only a placebo. In both studies, the subjects who received the testosterone boost behaved in a more upstanding manner than those who did not.


The results from one of the studies, showing that those who were administered exogenous testosterone gel cheated less (by claiming a larger payoff) in a coin game

We even suggested why this might be so.

‘It stands to reason – or at least it doesn’t offend common sense – that a man who feels more secure in his masculinity is probably less likely to behave badly, and the two studies mentioned above do go some way towards substantiating this, while also leaving us in no doubt that the relationship between biological factors and behaviour is complicated, even before we begin to consider other factors like environmental and social causes.’

Now, we’ve uncovered another study which bolsters the conclusion of these two papers on honesty: in the sexual realm, more testosterone may make a man eschew novel sexual stimuli for the familiar. In short, by extension, being high T may increase a man’s feelings of attachment for his partner.


The study, in the journal Hormones and Behaviour, was set up to investigate sexual interest and its relation to testosterone. The study took place over the course of a month, and measured each man’s interest in visual sexual stimuli across three sessions, as well as his testosterone levels.

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The procedures were as follows:

‘Fifteen men aged 23-28 viewed pictures of couples engaged in sexually explicit activity. Each session included a unique set of 72 pictures depicting heterosexual oral sex or intercourse presented in randomized order. Participants controlled how long they viewed each picture, with viewing time indicating sexual interest. Men’s testosterone (T) levels were assayed from blood spots obtained prior to viewing the pictures.’

The images were taken from porn websites after selection by a panel of (s)experts (!?) for their ‘arousability’. The test subjects were shown images of ‘oral sex to male, oral sex to female, female dominant intercourse facing male partner, female dominant intercourse away from male partner, male dominant intercourse from front of female partner and male dominant intercourse from behind female partner.’

The subjects had complete freedom to choose how long they looked at the pictures.

Although the researchers expected that the men would look longer at the images if they had more testosterone in their blood – which is what happened – they did not expect that this relationship would be stronger the more familiar the pictures became.

‘Overall, T and viewing time were positively correlated; however, the strength of this relationship varied by test session. T was marginally correlated with viewing time during the first session (r=0.43) and not significantly correlated with viewing time on the second session (r=0.16). During the final test session, when habituation might influence male interest in the stimuli, T was strongly correlated with viewing time (r=0.80).’

What this suggests, interestingly, is that rather than preventing habituation – which we might see as a euphemism for ‘domestic bliss’ – higher testosterone levels seem to encourage it. Put simply, rather than making men want to seek out endless novel sexual stimulation, higher levels of testosterone make them favour sexual stimulation in familiar settings. The researchers believe that men are driven to chase after women not be testosterone, but by other hormones or internal factors.

So if you’re looking to bring an end to ‘toxic’ sexual behaviour in men, testosterone may be your best friend – and not your worst enemy.


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