Speaker 1: Welcome to brain Stuff, a production of I Heart Radio,
Speaker 1: Hey brain Stuff, Lauren bog Obam Here. The long held
Speaker 1: and much perpetuated belief that dogs have a sense of
Speaker 1: smell superior to their trusty humans is total bunk, according
Speaker 1: to a review published in the journal Science. The author
Speaker 1: was Rutgers University sensory neuroscientist Dr John McGann, who sniffed
Speaker 1: out the truth by reviewing years of prior olfactory related
Speaker 1: research and comparing brain's responses to smelly stimuli in mice, dogs,
Speaker 1: and humans. Before the article this episode is based on,
Speaker 1: has to Work, spoke with McGann via email. He said,
Speaker 1: when we started working with people, it was impressive how
Speaker 1: excellent the human sense of smell really is. And I
Speaker 1: started closely reading the many years of previous work on
Speaker 1: the subject. So where did the idea of canines as
Speaker 1: superior smeller has come from? McGann traced it back to
Speaker 1: the works of one Paul Brokaw, a nineteenth century era
Speaker 1: neuro anatomist. Brokaw dubbed humans as non smellers without any
Speaker 1: sort of sensory testing to back that up. McGann wrote
Speaker 1: in his review he believed that the evolutionary enlargement of
Speaker 1: the human frontal lobe gave human beings free will at
Speaker 1: the expense of the old factory system. Brokaw also noted
Speaker 1: that other mammals feature old factory bulbs that are much
Speaker 1: larger in proportion to the rest of their brains than
Speaker 1: those in human beings. For example, of primates and humans
Speaker 1: have an old factory bulb making up just zero point
Speaker 1: zero one percent of the brain by volume, which compared
Speaker 1: with two percent of the average mouse brain can seem
Speaker 1: a little paltry, but this doesn't make humans any worse
Speaker 1: at smelling. McGann explained, the human bulb is a very
Speaker 1: small percentage of the human brain, which is part of
Speaker 1: the origin of the myth that humans are bad smellers,
Speaker 1: but it's actually quite large in absolute terms, much bigger
Speaker 1: than a mouse, say. It's also richly interconnected with many
Speaker 1: other brain regions that are larger and do more powerful
Speaker 1: computations in humans. That's not to say that certain species
Speaker 1: don't excel at identifying specific types of sense. However, in
Speaker 1: the research, dogs were better at discerning between urins and
Speaker 1: humans were better at differentiating between wines. Began wrote in
Speaker 1: the review when an appropriate range of odors is tested.
Speaker 1: Humans outperform laboratory rodents and dogs in detecting some odors
Speaker 1: while being less sensitive to other odors. He notes that
Speaker 1: humans are even capable of following scent trails in the
Speaker 1: great outdoors. He said via email, it's difficult to make generalizations,
Speaker 1: but I think it's fair to say that though the
Speaker 1: human olfactory system is different than the rodent or dog
Speaker 1: olfactory system, it's not worse than they are. And in
Speaker 1: addition to being more powerful than you previously thought, the
Speaker 1: human sense of smell is actually more important too. Smells
Speaker 1: can cause us to recall specific associated memories and can
Speaker 1: also elicit related behavioral and emotional responses. Personal odor can
Speaker 1: also relate information about anxiety, stress levels, even reproductive status,
Speaker 1: all things we once thought were only communicated by non
Speaker 1: human animals. McGann said smell is underappreciated in our daily lives.
Speaker 1: Most of the flavor of food is actually its smell
Speaker 1: reaching the nose by going up through the back of
Speaker 1: the throat. We're also beginning to understand that humans communicate
Speaker 1: information about our genetics, diet, and emotional state through individualized
Speaker 1: body odors that influence the behavior of other people, often subconsciously. Furthermore,
Speaker 1: our sense of smell begins declining somewhere around the age
Speaker 1: of sixty, and an improperly functioning olfactory system can be
Speaker 1: a symptom of neurodegenerative diseases like Alzheimer's or Parkinson's. McGann
Speaker 1: said loss of smell can thus be veried stressing for people,
Speaker 1: which is one of the reasons I wrote this article
Speaker 1: and to increase popular awareness of the importance of smelling
Speaker 1: humans and hopefully encourage more emphasis on the development of
Speaker 1: all factory medicine. Today's episode is based on the article
Speaker 1: a human sense of smell is actually as good as
Speaker 1: the dog's on house toff works dot com, written by
Speaker 1: Leo Hoyt. Brain Stuff is production of I Heart Radio
Speaker 1: in partnership with how stuff works dot Com, and it's
Speaker 1: produced by Tyler Klang. Before more podcasts from my heart Radio,
Speaker 1: visit the I heart Radio app, Apple Podcasts, or wherever
Speaker 1: you listen to your favorite shows.