Sizing up dogs

Why are dogs of interest to human geneticists? Dog breeds display an extraordinary amount of variation in skeletal structure, including overall size, leg length and width, and variants of skull shape. Breeds thus present geneticists with great opportunities for studying the genetics underlying common traits that have become fixed as part of various breed standards. Many traits were selected because they offered particular advantages to their human owners: dogs have been bred to hunt (sight hounds and scent hounds); herd (border collies and Australian shepherds); race (greyhounds); draft (huskies); and search (bloodhounds and German Shepherds). Many breeds have a morphology that benefits their tasks; for instance, short-legged dogs are ideal for fox and rabbit hunting as their short stature allows them to more easily catch small prey.