Photo caption: In terms of smell-abilities, polar bears are at the apex. Dolphins, meanwhile, can’t smell. (Their blowholes evolved only for breathing.)

You are watching your favorite TV crime show, and—spoiler alert—the bad guy escapes. It’s dark and rainy, and police officers tear through the scene. Amid the chaos, you see a lone dog sniffing out a trail.

How did man’s best friend turn serious sleuth? You might have heard that pups have a sense of smell much more powerful than our own. The detectives aren’t putting their own noses to the ground, after all.

Long before doghouses and Milk-Bone treats, dogs and other animals developed smelling superpowers to track prey and other food and to avoid predators.

Dogs, cats and rodents get a “second chance” to smell, which humans don’t. As those animals inhale, some air reaches the odor-detecting and processing (olfactory) region above the nasal passage, which helps identify the smell, while the rest moves to the lungs. Then during exhalation, the air again passes that region.

We humans have 5 million sensors above our nasal passage that detect smells. Sounds like plenty, right? Well, dogs have 100 to 300 million—but even they have competition. A bear’s sense of smell is estimated to be seven times better than a bloodhound’s. Black bears and polar bears can detect food up to 20 miles away.

Maybe next time a bear should lead the search party. 

Special thanks to Claire E.J. Cheetham, an assistant professor of neurobiology, for helping us sniff out this story.

Read more from the fall 2026 issue.