Researchers say that dogs can use their sense of smell to detect the age, gender, and mood of other dogs. Dogs can even be trained to detect explosives and illegal drugs. While humans mainly use sight to investigate their surroundings, dogs use their sense of smell. They “read” with their nose.

 Consider: A dog’s sense of smell is thousands of times more refined than ours. According to the U.S. National Institute of Standards and Technology, a dog “can detect certain compounds at parts per trillion. This feat is the equivalent of tasting about a quarter teaspoon of sugar dissolved in an Olympic-sized swimming pool.”

 What accounts for the dog’s superior sense of smell?

•   A dog’s nose is wet and is therefore better able to capture scent particles.

•   A dog’s nose has two airways​—one for breathing, another for smelling. When a dog sniffs, air is directed to the part of the nasal cavity that contains scent receptors.

•   A dog’s olfactory region can measure 130 square centimeters (20 sq in.) or more, whereas a human’s measures only 5 square centimeters (0.8 sq in.).

•   A dog can have up to 50 times as many scent receptor cells as we do.

 All of this enables a dog to differentiate between the components of a complex scent. For example, we can smell soup, but a dog can detect every ingredient in the recipe, according to some experts.

 Researchers at the Pine Street Foundation, a cancer research institute, say that the dog’s brain and nose work together to be “one of the most sophisticated odor detection devices on the planet.” Scientists are developing electronic “noses” to detect explosives, contraband, and disease, including cancer.

 What do you think? Did the dog’s sense of smell evolve? Or was it designed?