ATTRACTION POWER OF PHEROMONES CHALLENGED
27 October 2006 - Swedish Research Council

His study, “Putative Pheromones and Their Effects in Humans" investigated the importance of pheromones* in humans. The findings show that these substances are indeed found in humans, but they do not influence our behaviour to any great extent.

- Scientifically, the indications are weak that pheromones play any role at all in human behaviour. Pheromones are primarily associated with sex and reproduction. They are, quite simply, very weak scent substances found on our skin and in urine. When excreted, the power of attraction over the opposite sex should increase.

This effect is well established in insects and mammals. Even very low concentrations in the air will influence individuals of the same species.

- But people need more than that to become attracted to each other, says Mats Olsson.

Reaction not the same as attraction
Mats Olsson has studied pheromones in several experimental studies. His observations suggest that people do indeed react to pheromones. But it is a long step from reaction to attraction.

- For instance, we have studied how women feel after being exposed to a male scent. The substance is a steroid called androstadienone and is found in sweat. The women were exposed to pheromones at such low concentrations that it was impossible for them to be aware of the scent, and we also masked it with another strong odour.

- We observed a change in the mood of women who participated in the experiment. The women felt more positive and focused in comparison to women in the control group. We also measured their heart rate and skin temperature and saw a change even in these functions.

- It is worth noting that the women, all of whom were heterosexual, reacted when the trial leader was a heterosexual male. When we used a female trial leader we found no reaction. Mats Olsson interprets this to mean that people are contextual beings who are not driven by individual stimuli, but by the situations within which we find ourselves.

Mats Olsson also observed that the brains of men and women react differently to the male pheromones androstadienone and the female equivalent, estratetraenol that is excreted in urine.

- While androstadienone influences the hypothalamus, which is a hormone-regulating area in the female brain, we instead see reactions in the hypothalamus in men when they are exposed to estratetraenol.

Fertile women more sensitive
Another experiment performed by Mats Olsson and his colleagues was to study whether women could detect the odour of androstadienone. The women were divided into three different groups; one group was in the fertile phase of the menstrual cycle, the second group was in the infertile phase, and the third group took birth control pills.

They found that the women in the fertile phase of the menstrual cycle were more sensitive to pheromones than the other groups were. This suggests that women, when they have the greatest potential to become pregnant, are more sensitive to male skin scents than at other times.

Nevertheless, Mats Olsson warns that we need to be cautious about drawing conclusions on how pheromones affect humans.

- This only tells us that something biologic occurs, but we have no research to reliably show that it would influence our actual behaviour.

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