The answer lies in the use of pheromones as a mode of feline communication. Pheromones are volatile substances that human beings aren’t able to perceive, but that cats detect through their sense of smell and their vomeronasal organ, also referred to as the Jacobson’s organ. This is a sensory organ located at the end of the nasal cavity. Through a mechanism called the flehmen response, cats inhale small puffs of air by raising their upper lip. From there, the air reaches the vomeronasal organ, where these signals are detected.
Pheromones are released through specialized glands that cats have in different parts of the body: around the nose, on the sides of the head, on the plantar pads, at the base of the tail and around the anus. Pheromones have several functions; in general, they serve to mark the cat’s territory, but they also send different messages to people and others cats. Some of these messages are related to sexual attraction or to give off warning signs, but the function that concerns us here is that of social and territorial marking—in other words, “this territory or human is mine.” These specific pheromones are released through the glands on the face and head, which is why they especially rub these parts against objects and people.