Now, certain physical and behavioral traits may be linked. In the famous "Farm-Fox" experiment launched by geneticist Dmitri Belyaev,

Now, certain physical and behavioral traits may be linked. In the famous "Farm-Fox" experiment launched by geneticist Dmitri Belyaev, the researcher bred silver foxes who were friendly towards people, creating and increasingly reliable stock of tame foxes. As he bred his tame foxes, their appearances changed over the generations; their pricked ears folded over and they became more puppy-like in appearance. Border Collies suffer disproportionately from noise phobia, which may be a byproduct of a desired trait—the one that makes Border Collies able to obey a voice command or whistle given from hundreds of feet away.

However, we must be careful not to assume that, just because a trait may have a genetic component, it exists across members of a breed. After all, we've established that Border Collies raised for the show ring show different behaviors than Border Collies raised for work, and we'll need more research into whether show Border Collies are suppressing a natural urge, or if they differ genetically from their working cousins. And behavioral traits that we may think of as common in certain breeds aren't necessarily universal; Janis Bradley's essay in The Bark about her lazy greyhound—and whether greyhounds are particularly predisposed toward racing behavior—is particularly enlightening.