Allen's rule

Meaning

Proper Noun

• An ecogeographic principle broadly stating that animals adapted to cold climates have relatively short limbs. Specifically, homeothermic animals in hot climates have low volume-to-surface ratios, and homeothermic animals in cold climates have high volume-to-surface ratios, due to thermal adaptation.

Origin

• Formulated by Joel Asaph Allen in 1877.