Earthling, Terran, and Gaian are terms commonly used in science fiction to identify humans as opposed to extraterrestrials. The literary effect aimed for is a distancing effect, inviting the readers to contemplate their own species as it might be seen from an external point of view. Especially in 1950s science fiction, use of the terms is a conscious reversal of common assumptions of anthropocentrism or human exceptionalism, and may be an example of a demonym.