Changes

A '''pheromone''' is a type of ectohormone secreted by an individual and perceived by a second individual of the same or similar species, thereby producing a change in the sexual or social behavior of that individual.<refname="farler2012">Pheromone. (n.d.) Farlex Partner Medical Dictionary © Farlex . (2012). Retrieved June 11 2021 from https://medical-dictionary.thefreedictionary.com/pheromone</ref>

Pheromones are important in many animal species but, until recently, were thought to be unimportant in humans. It has now been shown, however, that the timing of ovulation in women can be controlled by pheromones from the armpit. This is believed to be the explanation of the fact that women living together will frequently develop synchronized menstrual cycles.<refname="collins2004">Pheromone. (n.d.) Collins Dictionary of Medicine. (2004, 2005). Retrieved June 11 2021 from https://medical-dictionary.thefreedictionary.com/pheromone</ref>