title: Cannibal's relief:  the origins of sex.
abstract: Microorganisms in the gut of a cockroach resemble those that lived on earth 2000 million years ago.  One of their activities, eating each other, may hold the key to the history of sexual reproduction in today's animals and plants.
authors.forename: D
authors.initials: D
authors.lastname: Sagan
authors.forename: L
authors.initials: L
authors.lastname: Margulis
mesh_terms: D000818:Animals; D018407:Bacterial Physiological Phenomena; D005075:Biological Evolution; D002190:Cannibalism; D002468:Cell Physiological Phenomena; D003227:Conjugation, Genetic; D004247:DNA / Q000502:physiology; D005306:Fertilization / Q000235:genetics / Q000502:physiology*; D008540:Meiosis / Q000235:genetics / Q000502:physiology*; D008938:Mitosis / Q000235:genetics / Q000502:physiology*; D011235:Predatory Behavior; D012098:Reproduction / Q000502:physiology*; D012100:Reproduction, Asexual / Q000502:physiology; D012723:Sex
chemical_list: D004247:DNA