True or False: Selective breeding has significantly changed the physical traits of dogs over time.

The story behind the answer

True. Humans have selectively bred dogs for desired traits, dramatically reshaping their bodies over time. That’s why one species can range from tiny Chihuahuas to towering Great Danes, with skulls from long-nosed collies to flat-faced bulldogs, legs from the short dachshund to the sprinting greyhound, and coats from hairless to double-insulated.

Dogs descend from gray wolves, but most modern breeds emerged in the last few centuries as kennel clubs codified breed standards. Intense selection can bring trade-offs—like breathing issues in brachycephalic breeds or hip problems in large dogs. Memory tip: “One wolf, many forms—people picked the norms.” Selective breeding is like sculpting: by choosing which dogs reproduce, humans chiseled today’s remarkable variety in size, shape, and function.