Before revision: Extraterrestrial life The mediocrity principle suggests, given the existence of life on Earth, that should life exist elsewhere in the universe, it will typically exist on Earth-like planets.Chaisson, Eric, and Steve McMillan.
After revision: David Bates ascribed the mediocrity principle to Sebastian von Hoerner, who as early as 1961 wrote the following:Extraterrestrial life The mediocrity principle suggests, given the existence of life on Earth, that should life exist elsewhere in the universe, it will typically exist on Earth-like planets.Chaisson, Eric, and Steve McMillan.