Winning looks.

With milky eyes, splotchy skin, and jagged teeth, this dog--named Sam--wooed judges at the annual "World's Ugliest Dog" contest at California's Sonoma-Marin Fair. And even though Sam faced unsightly competition, he nabbed the ugly title.

Where does Sam get his looks? Old age is partly responsible. For instance, an eye disease called cataracts led to Sam's spooky white eyes. Also, this fur-free dog is part of a breed, or group of organisms that descended from common ancestors, called the Chinese crested hairless. Believe it or not, all 400 dog breeds--from bloodhounds to cockerpoos--belong to the same species Canis familiaris (KAY-nis FAH-mil-ee-air-us). But different breeds of dogs within this species can have traits, or characteristics determined by genes, that are worlds apart. For example, a slobbering, big-headed Saint Bernard would never be mistaken for a prancing, curly-haired Poodle.

This canine diversity is the result of generations of breeding, explains Sophia Kaluzniacki, a veterinarian in Arizona. To begin the breeding process, dog breeders mate dogs with desired traits, like short snouts. The selected parents each pass down half of their genes (units of hereditary material) to their offspring. That way, each pup acquires slightly different genes. Then, breeders choose pups with the "ideal" snout to mate in the next round.

Generations of breeding have resulted in Chinese crested dogs with similar characteristics, including tusklike teeth and a friendly disposition. But not all hairless dogs are created equally. "The hairless gene manifests itself in a variety of ways, ranging from no hair to patches of hair," Kaluzniacki says. Some have thick tufts of hair on their heads and tails. Sam's mane however, consists of just a few sparse wisps.

Bare skin has its advantages, such as keeping fur-seeking fleas at bay, and its disadvantages. "The less hairy a dog, the more likely it will develop blackheads," says Kaluzniacki. That's because without hair to keep pores open, these tiny holes get clogged with acne-producing oils. Being so naked, Sam's body is covered with blackheads.

But looks can be very deceiving: According to Sam's owner, this dog is sweet and cuddly.