The search for human pheromones: the lost decades and the necessity of returning to first principles

Abstract

As humans are mammals, it is possible, perhaps even probable, that we have pheromones. However, there is no robust bioassay-led evidence for the widely published claims that four steroid molecules are human pheromones: androstenone, androstenol, androstadienone and estratetraenol. In the absence of sound reasons to test the molecules, positive results in studies need to be treated with scepticism as these are highly likely to be false positives. Common problems include small sample sizes, an overestimate of effect size (as no effect can be expected), positive publication bias and lack of replication. Instead, if we are to find human pheromones, we need to treat ourselves as if we were a newly discovered mammal, and use the rigorous methods already proven successful in pheromone research on other species. Establishing a pheromone relies on demonstration of an odour-mediated behavioural or physiological response, identification and synthesis of the bioactive molecule(s), followed by bioassay confirmation of activity. Likely sources include our sebaceous glands. Comparison of secretions from adult and pre-pubertal humans may highlight potential molecules involved in sexual behaviour. One of the most promising human pheromone leads is a nipple secretion from the areola glands produced by all lactating mothers, which stimulates suckling by any baby not just their own.

Androstadienone’s influence on the perception of facial and vocal attractiveness is not sex specific

“…Our design discredited sex specificity in accordance with the results of other studies (Hummer and McClintock, 2009), but the fact that, in real-life conditions, a substantial part of the population is anosmic to androstadienone (25% of the participants in our study) must also be taken into consideration when discussing the role of androstadienone. Indeed, this is another reason to doubt that androstadienone acts as a pheromone (Wyatt 2015).…”

“…Indeed, if it were, why would this compound also be found in human secretions that are most likely not involved in male-female attractiveness, such as amniotic fluid (Loos et al, 2014), a finding that further challenges the presumptions about the sex specificity of androstadienone production? Why would anosmia to androstadienone have such a high prevalence in the population, whereas deleterious mutations of the genes responsible for the detection of a human pheromone should be counter-selected (Wyatt, 2015)? Studies focusing on androstadienone and related compounds are increasingly being criticized (Doty, 2014(Doty, , 2010Wyatt, 2015).…”

“…Why would anosmia to androstadienone have such a high prevalence in the population, whereas deleterious mutations of the genes responsible for the detection of a human pheromone should be counter-selected (Wyatt, 2015)? Studies focusing on androstadienone and related compounds are increasingly being criticized (Doty, 2014(Doty, , 2010Wyatt, 2015). These criticisms point to the fact that many researchers use the term "human pheromone" when they study this family of compounds, although no evidence of pheromonal effects has been rigorously demonstrated thus far.…”

“…Precise definitions have been proposed for the concept of pheromone (Beauchamp et al, 1976;Karlson and Lüscher, 1959;Wyatt, 2010), 1 but so far studies in humans have not managed to identify molecules fitting these criteria (Wyatt, 2015) and some authors are skeptical about the existence of pheromones in humans (Doty, 2010). Studies investigating putative pheromonal properties of some compounds (mostly those cited earlier, chosen on the basis of questionable arguments) have tested, using varied methodologies, their influence on human behavior and physiological and emotional states.…”

“…More generally, this study aimed to present new elements to determine whether it is relevant -for a better understanding of human chemosignaling in mate choice -to keep focusing on this particular compound rather than on others (Wyatt, 2015). With this aim, we collected attractiveness evaluations of male and female participants, the latter being allocated to a "fertile" group or a "non-fertile" group according to the phase of their menstrual cycle at the time they participated in the study.…”