The View from a Drawbridge

Have you ever wondered why we all have two nostrils rather than just having one big one? After my most recent battle with a freakish virus whose main weaponry seemed to be the yellow snot of death, I can tell you that I certainly have. But then, my wonderment tends to veer toward the bizarre even on the best of days.

During a recent chat with a friend in which she mentioned that she heard that dogs smell in stereo, a quick google search revealed that humans smell in stereo, too. I was immediately intrigued. I mean, we all know we see in stereo (think depth perception and double vision), and we hear in stereo (which is why we can often detect which direction a sound is coming from), but smelling in stereo never occurred to me.

I know I have a relatively refined sniffer. I often detect odors that others do not. If one of our dogs has an accident in the house, I usually find the piddle spot long before Dear Husband does. But I always thought my sense of smell was a solitary unit of sorts, and that I was just aiming myself in the direction where the smell is strongest.

But it turns out that each nostril is providing distinct information. Each one causes different brain activity. Scientists also have determined that this stereo smelling aids us in navigation. We may not consciously sense that one nostril is smelling something more strongly than the other, but in experiments, people did tend to go in the direction that had the higher concentration of scent. (If you need a giggle, check out this YouTube video entitled Stereo Smelling First Field Test.)

We shouldn’t get all cocky, though. Dogs still have 50 times more olfactory receptors than we do. And bloodhounds, the king of trackers, have 60 times more olfactory receptors than we do. Still, knowing that we smell in stereo has me thinking about scent in a whole new way.

Sources:

• https://www.npr.org/templates/story/story.php?storyId=6642887
• https://www.sciencealert.com/each-of-your-nostrils-smells-the-world-uniquely-study-reveals
• https://www.pnas.org/doi/full/10.1073/pnas.2004642117
• https://www.animalwised.com/the-sense-of-smell-in-dogs-4414.html

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