In today’s screen-based world, it can seem like we depend almost exclusively on what we see. Taste, touch and aroma seem to play a minor role in our daily lives. But it’s not like that. In reality, we rely on all of our senses to inform us about our surroundings, as well as to regulate our mood and physical state. And surprisingly, the most powerful of our senses is not sight, but smell. A particular scent can alter moods, evoke memories, and even determine our choice of mate, without our realizing it. (Remember that when we first come into the world, sight is not exactly our predominant sense.) Smell is the key.
The experiment carried out by the zoologist Claus Wedekind at the University of Bern (Switzerland) made quite clear the importance of the aromatic influence in relation to the choice of partner . A group of women had to assign degrees of sexual attractiveness based on the smell of shirts that men they did not know had worn for two days. What was surprising was that the volunteers had no problem making that classification conclusively.
The experiment of sweaty T-shirts –as it is usually called– and carried out in 1994, revealed that one factor almost always coincided with the classification: women chose the men with the greatest differences in the genes of the so-called main histocompatibility complex (MHC, for its acronym in English).
The more different the MHC is between parents, the greater immune resistance to disease the children they conceive will have. Later studies have also confirmed that we are attracted by the aroma of those with what would be a better idea, genetically speaking, to procreate.
The smelly experiment process
Wedekind analyzed a particular piece of DNA from a group of students, specifically looking at the major histocompatibility genes (MHC). The students were divided into 49 women and 44 men . The men were asked to wear plain cotton T-shirts for two nights while avoiding any substances (alcohol, cologne, etc.) that could alter their natural scent. After two days, the shirts were placed in cardboard boxes with holes, and the women were asked to classify the boxes by smell using three criteria: intensity, pleasure and sensuality.
Wedekind’s results seemed to show that women preferred the shirts worn by men with different compatibility genes than theirs , increasing the possibility that we would unconsciously select partners who would put our offspring with some genetic advantage . The experiment was controversial, but it altered scientific thinking about compatibility genes. And while the mechanism behind this phenomenon is poorly understood, that hasn’t stopped dating agencies from employing MHC typing as a matchmaking tool, for example. One lab that offers these kinds of tests to online agencies is a Swiss company called GenePartner, which states: “With genetically compatible people, we feel that rare sense of perfect chemistry.”
But how does the smell work, if it works? It has been shown that mice can, and do, detect compatibility genes by smell , and spiny fish also choose mates by smell, but in humans, the game is … a bit more complicated.
