Selfish Herd Theory
The theory that individuals within a population attempt to reduce their predation risk by putting other conspecifics between themselves and predators.
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Origin
British evolutionary biologist W. D. Hamilton proposed the theory in his 1971 paper "Geometry for the Selfish Herd," published in the Journal of Theoretical Biology. Hamilton reframed gregarious behavior not as altruistic cooperation for species survival, but as selfish strategy where individuals minimize predation risk by positioning conspecifics as shields. The theory built on Francis Galton's 1871 observation of animals seeking cover among others, challenging group selection theories prevalent in mid-20th-century evolutionary biology.
Updated February 22, 2026