Pheromones are chemicals found in body secretions that attract the opposite sex. They don't have a discernable smell, but humans have special detectors in their noses for pheromones. We respond physiologically to another person's pheromones, even if we cannot consciously smell them.

The word pheromone is derived from a Greek word meaning “to transfer excitement.” Body temperature, skin conductance, heart rate, and blood pressure are just some of the functions that can be affected by our reactions to our partner's pheromones. (Women taking oral contraceptives seem to be less responsive to pheromones.) Pheromones have also been isolated as the cause for synchronized menstruation cycles among women who live in close proximity over a period of time.

Male and female pheromones are excreted from glands in the hair follicles, the underarms, and the groin area. Some men and women are greatly attracted to the smell of their partners' underarms and hair. Try burying your nose in your partner's hair the next time you want to become aroused.