Wake up and Smell the Pheromones
(May 2nd, 2015) Is human behaviour controlled by pheromones or not? This is still a controversial topic. Tristram Wyatt has his own ideas about the past, present and future of human pheromone research and shares them with us.
Research has shown the import effects of pheromones on the behaviour of ants, bees and other insects. But do humans also behave according to what they smell? In a recent review Tristram Wyatt, Emeritus Fellow at the University of Oxford, points out the potentially important role of pheromones for human behaviour but also describes that there is no solid evidence for the existence of human pheromones. Therefore, the search for them should restart from scratch.
Pheromones are molecules acting as signals between members of the same species. They are attributed to a particular group of organisms, not to a particular individual. Most pheromones are detected by smell. However, not every smell is elicited by pheromones. They can be big or small molecules, or they can be a complex of a large number of different molecules. The role of pheromones is to alter sexual or developmental behaviour of an individual in order to ensure the survival and prosperity of the species as a whole.
According to Wyatt, evidence that the four human steroid molecules identified so far - androstenone, androstenol, androstadienone and estratetraenol – are truly pheromones does not exist. In addition, he comments that currently there is no robust experimental method to determine whether humans have pheromones, and those four above-mentioned molecules “have never been shown to be biologically relevant”. Therefore, it would be wise to look for or devise totally new methods. These should be based on the assays used to identify insect and animal pheromones. Researchers could, for instance, compare the content of chemical gland secretions between adults and children before puberty. Also, molecules binding to human olfactory receptors could be potential human pheromones.
One of the most important aspects of human pheromone identification, as Wyatt suggests, would be careful description of experimental set-ups before initiating the actual experiment. This would avoid bias by stopping the experiments once the desired data are collected, without carrying out further replicate studies.
He also suggests extending the search for pheromones to include the whole human body area, including armpits and sebaceous glands. “The most promising possible human pheromone is the mammary pheromone secretion, which appears to cause all human babies to search and suckle on the nipple. Successfully starting and completing the first milk meal is crucial to the healthy survival of babies. Yet some mothers seem to produce more secretion and their babies start to suckle more quickly. If the molecules of the mammary pheromone can be identified and synthesised, then mothers not producing as much as others could add the synthetic pheromone to their nipples and facilitate suckling by their new born baby,” says Wyatt.
Wyatt states that the greatest challenge in human pheromone research would be the cultural conditioning of humans responding to odours. But there are other challenges, like underfunding and that human sexual behaviour research has a low priority.
“It may be that we will find that there are no pheromones in humans. But we can be sure that we shall never find anything if we follow the current path. We need to start again,” concludes Tristram Wyatt.