Once the only form of communication between animals, pheromones are chemical messengers from one being to another that affect the behavior of the receiver. From amoebas to insects to mammals, all animals have this ability. Detected in mammals through the vomeronasal organ in the nose, these chemicals vary and convey different messages. Some may tell something about a readiness to mate, others serve to define territory or announce aggression. A whiff of pheromones from a female mouse, for instance, will make a male mouse start mating immediately. Pheromones from male mice produce other changes like making him more aggressive.

In humans, the vomeronasal organ does not function as well as in most mammals, and we have lost the ability to consciously detect pheromones. There is, however, a body of scientific evidence that we are subconsciously influenced by pheromones and that to a degree, pheromones still dictate much of human sexual interaction.

Some of this evidence comes from a study at the University of Kentucky when researchers sprayed the male pheromone, androsterone on pictures of men of average sexual attractiveness. When showed to women, it was discovered that men in the androsterone-sprayed pictures were rated as more attractive.

Androsterone pheromone can be bought in a concentrate form or mixed with a fragrant cologne. A survey of 100 men who used a popular brand of androsterone pheromone concentrate reported the following:

92% noticed an increase in women making eye contact
89% noticed more smiles from women
76% reported strange women starting conversations with them
81% reported being approached by women they didn't know
68% reported an increase in dates and other forms of sociosexual contact

Androsterone pheromone also seems to have an affect on other men, making someone who has more seem more intimidating. Many men have reported using the androsterone pheromone in sports or business environments to be noticed and gain respect.