Pheromones have a very important role in evolution not just for humans, animals and even certain plants.
Pheromones are naturally occurring odorless substances that are emitted by fertile bodies. They work by conveying an airborne signal that provides information to, and triggers responses from, the opposite sex of the same species. They allow members of the opposite sex to subconsciously sense when others are ready for reproduction.
Some scientists have even speculated that pheromones can lead to the synchronization of menstrual cycles in females.