Allen's rule

noun

Definition of Allen's rule 

: a statement in zoology: protruding body parts (as ears, tail, legs, bill) of warm-blooded animals are relatively shorter in cooler than in warmer parts of the range

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First Known Use of Allen's rule

1937, in the meaning defined above

History and Etymology for Allen's rule

after Joel A. Allen

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The first known use of Allen's rule was in 1937

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