Animals living near colder climates are bigger in size because being heftier allows them several benefits like reducing body heat loss, researchers said.

For most species of vertebrates, body mass increases the closer you get to the poles. The bigger you are, the more fat you can store to help you get through the winter.

For many types of animals, it pays to be bigger in the colder climates that exist at high latitudes and altitudes.

Heftier animals have a smaller surface area-to-volume ratio, which helps reduce heat loss — a pattern known as Bergmann’s Rule. A more massive organism has a smaller surface area-to-volume. Another reason is that the bigger you are, the more fat you can store to see you through the winter of colder climates. More nutritious foods also fuel bigger body size closer to the poles.

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