self-preservation instinct
the fundamental tendency of humans and nonhuman animals to behave so as to avoid injury and maximize chances of survival (e.g., by fleeing from dangerous situations or predators). In his early formulations of classic psychoanalytic theory, Sigmund Freud proposed that self-preservation was one of two instincts that motivated human behavior, the other being the sexual instinct. In his later formulations, he combined both instincts into the concept of Eros, or the life instinct, and opposed them to Thanatos, the death instinct. Also called self-preservative instinct; survival instinct.