In what is now referred to as the “sweaty t-shirt test” research shows that our sense of smell is an incredibly powerful determinant to mate choice. Current studies have shown that we find the scent of individuals who are more genetically distant (less related) to us more attractive.
It has been known for some time that pheromonal exchange acts as chemical attractants between males and females of the same species. However, it was not until recently that mate selection and mate preferences have been pinpointed to a set of genetic cellular markers within chemical scent pheromones.
Each individual, even identical twins are utterly unique in this area. Each individual possesses “self” markers unique to the individual are expressed on the body cell surfaces. These cell surface markers allow the body’s immune system to differentiate its own cells from foreign cells, tissues, viral and bacterial pathogens that it would mark as dangerous and destroy. For this reason organ transplants and tissue grafts from another person are often rejected by the recipient’s body and why successful organ transplant recipients will need to take immunosuppressant drugs for the rest of their lives.
These cellular self markers are called major histocompatibility complex proteins (MHC). In the study now dubbed the “sweaty t-shirt test” 49 men and 44 women students were genotyped for their genetic cellular markers or MHC protein types. The men in the study were each given a t-shirt to wear for two nights. The women were then asked to describe the scent of each shirt with regard to intensity, pleasantness and sexiness. The study found that the women preferred the scent of t-shirts belonging to men with MHC complexes the most diverse from their own. Alternately, women found the scent men who had MHC proteins closer to their own less pleasant. This MHC-scent preference was found to be reversed when women were taking oral contraceptives.
Penn, Dustin and Wedekind, Claus. 2000. MHC genes, body odours, and odour preferences. Nephrology Dialysis Transplantation. 15: 1269-1271.