FEMALE PHEROMONES AND MALE PHYSIOLOGY

by Astrid Jütte
 
A pheromone is a scent one emits, that alters the behaviour of his social or sexual partner. They are quite fascinating because of eliciting non-conscious behavioural (and physiological) reactions. In the human brain processing of scents is more direct than of e.g. optical stimuli.
The human animal emits pheromones on a lot of different sites on its body. Sweat and its bacterial catabolites is one of the predominant smells. Females produce an additional scent: volatile fatty acids in their vaginal secretions, called "copulins". The fatty-acid-composition changes in the female menstrual cycle as found by Michael et al. 1975 (Psychoneuroendoc. 1: 153-163).

The idea was to test if males are able to smell maximum fertility and if they are changing their behaviour and physiological state as a result of perceiving the scent.

I tested smells of synthetic copulins of three different days out of the cycle (of a menstrual, an ovulatory and a premenstrual day) against each other and against control (water).
106 male subjects had to rate independently photographs and voices of different females during inhaling one of the four scents. Furthermore I collected saliva-samples before and after sniffing the copulins (sniffing lasted approximately 20 minutes).

In contrast to expectations there was no significant difference between the ratings of males of the three scent-groups. Ovulation-smell had a slightly attractivity- and dominance-rating-diminishing effect in comparison to the two other scents.
Interestingly copulins caused over all more positive ratings than control (water). But the effect is graduated: a woman that is rated without smell as very attractive gains less through smell than an unattractive-rated
woman.
On the other hand saliva testosterone-levels of the ovulatory-smell test persons increased to nearly 150% of starting levels. The two other scents didn't alter testosterone-levels. During inhaling control (water) testosterone decreased significantly.
 

Take-home message:

• Ovulation seems to be hidden from males in that they don't change their ratings of females depending on the specific scents. The advantage for females could be not to have to defend from uninteresting but obtrusive males.
• The less attractive a woman the more she gains through the additional information of her natural smell that a man receives. The smell of copulins seems to make optical attractiveness less important for males. The same pictures can be drawn for dominance ratings and readiness of test-males, to meet the woman or pay a drink for her.
• Nevertheless males' physiology changes with the ovulation-scent to produce more watchful men. (Hightened testosterone levels seem to increase selective attention for erotic stimuli.)
•  Copulins seem to be real pheromones because of their independentness of pleasantness. Realize, that  copulins don't smell very pleasant (in fact they stink especially in high concentrations) yet attractiveness-ratings are better while smelling them than without them ! The behaviour-changing-effect part of the pheromone-definition could be mediated by increasing testosterone-levels.

Up to now the paper is only in german available. Please ask for the english version around winter 1998.