" Camels, unlike most animals, regulate their body temperatures at two different but stable states. During daytime in the desert, when it is unbearably hot, camels regulate close to 40°C, a close enough match to the air temperature to avoid having to cool by sweating precious water. At night the desert is cold, and even cold enough for frost; the camel would seriously lose heat if it tried to stay at 40°C, so it moves its regulation to a more suitable 34°C, which is warm "

― James E. Lovelock , The Revenge of Gaia