This belief isn’t based on empirical evidence, but on a 19th-century hypothesis about free will that has more in common with phrenology than with our modern understanding of how brains work. In a review published Thursday in Science, John P. McGann, a neuroscientist who studies olfaction at Rutgers University, reveals how we ended up with this myth. The truth is, humans are actually pretty good at smelling our world.
Researchers have estimated that a bloodhound’s nose consists of approximately 230 million olfactory cells, or “scent receptors” — 40 times the number in humans. Whereas our olfactory center is about the size of a postage stamp, a dog’s can be as large as a handkerchief — according to Allen, it is among the largest in canines. “The physical size of their olfactory area far exceeds most other working scent dogs,” he says. “The larger capacity combined with the desire to work makes them a very good tool.”
When a bloodhound sniffs a scent article (a piece of clothing or item touched only by the subject), air rushes through its nasal cavity and chemical vapors — or odors — lodge in the mucus and bombard the dog’s scent receptors. Chemical signals are then sent to the olfactory bulb, the part of the brain that analyzes smells, and an “odor image” is created.
There is no evidence that most mammals have a better sense of smell than humans.
I guess the border patrol should replace all their drug-sniffing dogs with drug-sniffing people.