Thursday, 4 April 2013

Investigating the love lives of the men and women who have no sense of smell

Around 1 in 7,500 otherwise healthy people are born with no sense of smell, a condition known as isolated congenital anosmia (ICA). So dominant are sight and hearing to our lives, you might think this lack of smell would be fairly inconsequential. In fact, a study of individuals with ICA published last year showed just how important smell is to humans. Compared with controls, the people with ICA were more insecure in their relationships, more prone to depression and to household accidents.

Now, in a follow-up paper involving the same 32 patients with ICA, Ilona Croy and her colleagues have looked at how this lack of a sense of smell affects their sexual relationships. The researchers' analysis uncovered an intriguing sex difference. Compared with 15 age-matched controls, the 10 men with no sense of smell reported having substantially fewer sexual partners in their lifetime (male controls averaged five times the number of partners). In contrast, women with no sense of smell averaged just as many sexual partners as women with smell.

On the other hand, the 22 women (but not the men) without a sense of smell tended to report feeling more insecure in their relationship with their current partner, than did the healthy controls. This insecurity was specific to their sexual partner and wasn't found in relation to friendships or maternal attachment.

Across both sexes, the impact of a loss of smell makes sense given the mounting evidence for the social importance of smell, for example we can use smell to detect other people's anxietypeople with more empathy are more likely to remember your smell; and smells convey at least some personality traits. Also, common sense suggests people without a sense of smell might worry about any odours they could be exuding without their knowledge. But the question still remains - why should not having a sense of smell affect men and women differently?

The researchers surmised that not having smell reduces men's "exploratory sexual behaviour", perhaps due to their lack of social confidence. Consistent with this interpretation, there was a negative correlation between the male (but not female) patients' levels of social insecurity and their number of sexual partners.

On the other hand, the researchers think the effect of a lack of smell on women makes sense in light of past research suggesting that smell is more important for their relationship security, than it is for men. For instance, a study published in 2008 found that a half of the women surveyed had worn someone else's clothes (usually a partner's) because of its smell, compared with just 13 per cent of men. Also relevant - the female patients' had lower social confidence than the female controls, and this correlated with their lack of relationship security.

Other research has shown that odour is more important to women than it is to men in choosing a partner: women supposedly prioritise good odour over good looks, men the opposite, although it's not clear how this fits with the current findings. Women also seem to have a superior sense of smell, on average, compared with men, and value the sense more highly.

Croy and her colleagues acknowledged the need for caution given their small sample size, but they said their results emphasise "the importance of the sense of smell for intimate relationships."


Croy, I., Bojanowski, V., and Hummel, T. (2013). Men without a sense of smell exhibit a strongly reduced number of sexual relationships, women exhibit reduced partnership security – A reanalysis of previously published data. Biological Psychology, 92 (2), 292-294 DOI: 10.1016/j.biopsycho.2012.11.008

--Further reading--
Humans can track scents like a dog.
Brain response to putative pheromones in homosexual men.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.


Elliot said...

This is interesting for me to read. I lost my sense of smell through brain injury and, regarding the 2nd paragraph, I can say that the complete opposite was true for me! I am certain the two are not connected in any way, however. For me, not being able to smell is completely inconsequential. I'm totally used to it and it doesn't impact my life at all, except I can't always tell when food has gone off!

Anonymous said...

I've been anosmic for 20 years. This is garbage according to hundreds of anosmics online. Depression is common; we've lost a sense, most of the sense of taste and the memories smell generates. But the rest is bunk. If this were more than poking fun at an uncommon disability, we'd see the same studies on blind and deaf people. Want to research anosmia? Chose a serious topic. Focus on cures. Focus on living with this disability. Otherwise, go bully someone else.

Anonymous said...

Please don't take this interpretation the wrong way but..

Sometimes I get home from work and decide based on a quick sniff if I need to have a shower before socialising. And I could do a quick breath check before chatting to girls (before I got married obviously)

Since women care a lot about smell could this inability to accurately self check explain these results?

For example colour blind people may wear clashing clothes, which may effect their success rates on singles nights?

Anonymous said...

I have had no sense of smell since 2002 due to a T.B.I. and my life has changed completely. I have no memory of what things taste like, for me its a texture issue and most likely will be for the rest of my life. My social life suffers as well because I never know when I smell unpleasant to other people. I live in terror every day because I never know if there is going to be a gas leak in my house, car, or any other building I enter. I end up getting food poisoning at least 4 times a year because I can't tell whether or not a food has gone bad. As far as paragraph 2 goes, pornography is more of a stimulant than actual sex is, which is devastating because I am married. I would like it if I was cured or helped out with this disability, but I can shit in one hand and wish in the other and I'm sure you know which one will fill up first.

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