Here’s a study that compares the olfactory epithelium of dogs to humans.
To learn more about the evolution of human olfaction, check out this study.
If you want to hear personal stories from people who can’t smell, visit this great series from the New York Times.
For more about the art of scent and how biophysicists engineer perfumes and artificial noses, check out this TED Talk.
The olfactory epithelium is an area inside the nose which is responsible for intercepting odors and passing them on to the brain. The mechanics of the olfactory epithelium are not fully understood; this structure contains a huge number of neurons, but the exact way in which they interact with and distinguish between smells is a bit of a mystery. The larger the area covered by the olfactory epithelium, the more neurons, and the better the sense of smell.