Why do they roll in stinky things?

Dogs have more than 300 million olfactory receptors in their noses, and humans only have six million. With all of these receptors, you would think that dogs’ high olfactory orientation would keep them away from foul and pungent smells like dead animals, but for them it’s like eau de stinky. “Your opinion of what makes an attractive scent is often different from ours,” says veterinarian Jennifer L. Summerfield, Brown Veterinary Service, DVM, CPDT-KA. “It is believed that the behavior of rolling in dead or particularly smelly things may have helped mask the dog’s odor, which could be useful for hunting.”