Plural of deme; in ancient Greece, these were subdivisions of citizens or districts within a city-state, especially Athens; in biology, they are local populations of organisms.
From Greek demos (people, district). In Athens, Cleisthenes divided the state into demes for administrative purposes. Modern biologists borrowed the term to describe breeding populations of a species.
The demes of ancient Athens were Cleisthenes' genius hack for breaking up tribal loyalty and creating a more democratic system—by randomly assigning citizens to geographical districts, he accidentally invented a more mixing way of building community.
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