ABSTRACT
To many people, there is something unsettling about a parasitic lifestyle, in which one organism habitually exploits another to secure its food, shelter or even its reproductive hormones. But for the comparative psychologist, parasites provide a unique opportunity to elucidate the evolution and development of social bonds between different species of organisms. Strictly speaking, parasitism is a form of symbiosis, a broad ecological concept that also includes mutually beneficial associations, such as between a human being and the intestinal microorganisms that aid its digestion. But parasitism is decidedly one-sided, with the parasite living at the expense of its host, and sometimes killing it. People are most familiar with physiological parasites, like viruses or fleas, which attach themselves to the skin or internal organs of larger organisms. But an even more fascinating interspecific relationship among animals is known as social parasitism. At first, “social parasitism” sounds like an oxymoron, because the term “social” denotes communication, cooperation and even altruism, all diametrically opposed to the patently selfish habits of parasites. The term is appropriate, however, because a social parasite’s infiltration into the host’s life is based on the same developmental and communicative processes that the parasite and host use for communicating with members of their own species.
