Body Odour as a Biological Signal

Body odour as a biological signal
Abstract of talk given by Dr. S Craig Roberts at the One Day Symposium, 21st May 2009

Dr S Craig Roberts, School of Biological Sciences, University of Liverpool, UK

Smell is critical in co-ordinating a variety of behaviours in animals. For example, in mammals, scent-marking using urine, faeces or secretions from specialised scent glands (like the musk glands of Moschus) is commonplace. Some taxa have a number of such glands (such as in the ungulates). Scent marks are often detected in the absence of the signaller, so encounters between individuals are typified by sniffing and information exchange. In contrast, we tend to think that information in human odour has been lost or at least plays a comparatively minimal role in human behaviour. Here I set out evidence to the contrary. First, I describe an experiment on the psychological effects of malodour and fragrance showing effects on men’s nonverbal behaviour and judgements of attractiveness by women. I then briefly present some anatomical evidence to compare with the animal examples, and some ethnographic evidence that suggests odour to be important in at least some societies.

If odour might indeed be important as a signal, what kind of information might it contain? I describe some evidence showing that body odour contains information permitting individual recognition and mate choice. Dealing with individuality, I distinguish between genetic and environmental components in odour signals, how these look in GC/MS profiles, and mention some applications, whether it is for biometrics or a baby recognising a mother’s breast. With respect to the role of odour on mate preference, I describe experiments showing that (i) the axillary odour of relatively dominant men is rated as more pleasant by women, (ii) that women’s axillary odour is rated as more attractive when they are ovulating than during the luteal phase, and (iii) that genetically compatible men smell more pleasant (although this appears to be somewhat disrupted by use of oral contraceptives).

Finally, I discuss the interaction between body odour and artificial fragrances. We still don’t really know whether we simply use fragrances to disguise our odour, or whether we might, in a more sophisticated way, select specific fragrances that positively and perhaps synergistically interact with our underlying odour. One experiment partly addressed this issue, testing whether preferences for specific perfume ingredients correlates with genotype, and finding that it does when raters judge fragrances as potential ingredients for a perfume for themselves (though not when judging fragrances as ingredients for a partner’s perfume). These results suggest that individual differences in perfume selection may be governed by the interaction between our genes and our nose, and that we may therefore be selecting a perfume that complements, rather than simply masks, our underlying odour.

Link to PDF file of Dr. Roberts Presentation: (1.56Mb Download)

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