Bergmann's rule https://en.wikipedia.org/wiki/Bergmann%27s_rule https://en.wikipedia.org/wiki/Bergmann%27s_rule The earliest explanation, given by Bergmann whe

Bergmann's rule https://en.wikipedia.org/wiki/Bergmann%27s_rule https://en.wikipedia.org/wiki/Bergmann%27s_rule The earliest explanation, given by Bergmann when originally formulating the rule, is that larger animals have a lower surface area to volume ratio than smaller animals, so they radiate less body heat per unit of mass, and therefore stay warmer in cold climates. Warmer climates impose the opposite problem: body heat generated by metabolism needs to be dissipated quickly rather than stored within.