Pheromone

Pheromones were chemicals produced by organic lifeforms. They were predominantly related to sex and sexuality. In weevils and moths, the female produced pheromones first, which signalled the nearest male to excrete his own chemicals in response. The two insects would then come together and mate. (PROSE: Syntax)

In the 21st century, a gaseous entity possessed a human woman; Carys Fletcher forcing her body to develop a series of pheromones that were irresistible to other humans. (TV: Day One)

By the 51st century, humans had evolved to produce more highly evolved pheromones, which made them more sexually attractive than their ancestors. (TV: Fragments)

By the time of the 309th Intergalactic Song Contest, Angvians' pheromones were so strong that they could even manipulate a Time Lord's sensibilities. (AUDIO: Bang-Bang-A-Boom!)

On the planet Jora, a living, sentient language, the Syntax, was created out of scientists' attempts to create a pheromone language. (PROSE: Syntax)