Alaskan Malamute

　　In hot weather, we can all see dogs panting with their mouths open; this is because dogs use their tongues and panting to dissipate heat. While panting, their tongues are repeatedly moistened to accelerate the evaporation and heat dissipation process. But why don’t dogs have sweat glands distributed over their bodies to help cool down? Is it enough for dogs to only rely on their tongues and sweat glands on their paws for heat dissipation?
　　Dogs only have highly efficient sweat glands on their paws, so they cannot cool down by sweating extensively through their bodies; during their evolution, staying warm in cold climates was clearly more important. Thick fur is more valuable than sweat glands for regulating body temperature.
　　It is worth mentioning that humans can detect odors at a level sixteen times less sensitive than dogs, also because the main function of a dog's tongue is heat dissipation.