Smelling

Cheer Up, Humans: Your Sense of Smell May Be Sharper Than You Think

We trust them to find drugs in schools, to track down missing people and to sniff out explosives in public places. But it turns out, dogs may not have as much of an olfactory advantage over humans as previously thought. A new review in Science disrupts a theory held for centuries that humans' sense of smell, well, stinks. "The idea that human smell is impoverished compared to other mammals is a 19th-century myth," says the researcher.

Humans Can Compete

John McGann, Ph.D., told the New York Times, "We're discovering, to our delight, that the human smell system is much better than we were led to believe." The Rutgers University neuroscientist and psychology professor reviewed past research into humans' sense of smell and how it compares to dogs, mice, and rats. McGann told NPR there are many experiments showing our sense of smell isn't far off from theirs. Studies are a wash: some have reported humans smelling some stimuli better than other animals, and some have demonstrated dogs, rats, or mice outsmelling us when it comes to different stimuli. But according to McGann, humans are indeed capable of tracking odor trails.

McGann believes it's important to learn as much as we can about how our sense of smell works. One important reason? Losing your sense of smell has been associated with the development of neurodegenerative diseases such as Alzheimer's and Parkinson's. In fact, a smell test is in the works for future diagnosis of Alzheimer's.

Does Size Matter?

After potentially disproving our major self-deprecating worldview, McGann tracked down the source of the rumor that humans can't smell very well. The culprit: a neuroanatomist from the 1800s named Paul Broca. "He classified humans as 'non-smellers' not owing to any sensory testing but because he believed that the evolutionary enlargement of the human frontal lobe gave human beings free will at the expense of the olfactory system," McGann wrote. In simpler terms, Broca thought that in exchange for skills in reasoning and abstract thought, we lost some of our ability to smell. Once this was an accepted belief, he says, researchers regularly misinterpreted data to fit within it instead of challenging it. Sigmund Freud even related mental illness to a poor sense of smell.

But even though a human's olfactory bulb may not take up as much of their brain as a mouse's or a dog's does, that doesn't mean our sense of smell couldn't also work very well. "The olfactory bulb is proportionately smaller in humans than in rodents, but is comparable in the number of neurons it contains and is actually much larger in absolute terms," writes McGann.

However, another psychologist who has researched dogs' sense of smell told NPR she isn't quite convinced the myth has been busted. "If the argument is, 'We are better smellers than we think,' I assent," Alexandra Horowitz said, but the Barnard College professor still believes "there is no serious comparison between the performance of a scent-tracking dog and a person."

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Key Facts In This Video

  1. Smelling is an essential part of your genes. 00:42

  2. People rate memories triggered by smell as more emotional than by sight or sound. 02:17

  3. Smells can occur in the womb before we're born. 02:41

Did The Ability To Smell Spark The Ability To Think?

Written By Ashley Hamer May 22, 2017