What the dog smells: The world of canine olfaction

Milo the AwesomeDog often punctuates our walks with fits of coughing, sneezing, and snorting. He’s not sick. He just sniffs thgerman shepherd dog trackinge ground vigorously enough to suck dirt and leaves right up into his nose. He takes his sniffing seriously and his days revolve around finding things to smell, and then smelling them.

It’s difficult to imagine what it is like to be Milo because while we humans are visual creatures, dogs are sniffing creatures. Dogs live with us, some of them in our homes, but at the same time, they live in a different world, a world of smells.

Nineteenth-century biologist Jakob von Uexküll called these different worlds umwelten. An animal’s umwelt, literally ‘life-world,’ is its subjective environment consisting of objects that it can perceive and with which it can engage. In the same physical space a dog, a bat, and a human have different umwelten because they can perceive and do different things. Humans can see the color red, but dogs can’t. Bats can echolocate and fly, but dogs and humans can’t.

We can begin to understand how a creature experiences the world by investigating how its senses work. If we want to understand the inner experiences of dogs, we need to study how they smell things.

This four and a half minute video, written by canine cognitive scientist Alexandra Horowitz, does a great job explaining the complexity of dog noses and dog olfaction.  It gets us started answering the question “what is it like to be a dog?”

This video taught me that when it comes to smell, there is a bigger difference between the umwelten of a dog and a person than I initially imagined.

This difference is based on more than the fact that dogs are better sniffers than humans, although they are. Dogs can smell odors at lower concentrations than we can–100 million times lower. To illustrate the scale of this difference, Horowitz describes dogs as being able to identify the individual components of a spritz of perfume in a football stadium.

It is not just dog noses that differ from human noses, dog brains differ too. Horowitz points out that the olfactory bulb in a dog’s brain is HUGE compared to ours, and that olfaction bypasses the “thalamus to connect directly to the brain structures involving emotions and instincts.” A dog’s sense of smell is orders of magnitude more powerful than ours, AND olfaction itself is an “immediate and visceral” mode of sensation. So when you think of what it is like to be a dog, you have to imagine a powerful sense of smell, likely producing emotionally charged sensations.

Dogs can smell in stereo. Just as we can tell what direction a sound is coming from, dogs can detect the direction that an odor is coming from. They can use scent to orient themselves in the world.

Finally, a dog’s sense of smell gives them the ability to travel back and forth through time. Dogs can smell into the past to determine who you had lunch with and what you ate. And they can smell into the future, alerting you someone approaching around the corner ahead of you.

Dogs can do different things with their sense of smell than we can do with ours. This impacts their emotions, their perceptions through time, and their ways of navigating the world.

This is exciting and distressing. Exciting because it’s fun to imagine having the superpower that is a dog’s sense of smell. Distressing because the gulf between what it is like to be me and what it is like to be Milo is wider than I thought.

Even though Milo and I spend most of our time at each others’ sides, we live in different umwelten.

German Shepherd smelling grass

5 thoughts on “What the dog smells: The world of canine olfaction

  1. What a great article. The idea that dogs smell in directions like we hear in directions is fascinating! I wonder if there are thresholds for dogs’ olfactory systems being overwhelmed? Does a strong perfume harm dogs? I wonder if they feel ill if there is too much mixing of scents?

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    • Thank you! I don’t know the answers to your questions. I’d imagine dogs would find some smells overwhelming. But on the other hand, Milo never passes upon opportunity to roll in something putrid. Alexandra Horowitz does some pretty cool research on dog olfaction, and we should ask her your questions.

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  2. I’ve often wondered what it is like to be one of my cats. Your post is helpful in pointing out that there could be many more dimensions in which a dog’s or cat’s experience might differ from my own, and from each other’s, than I had ever considered!

    On a related note, has anyone published work on the relationship between intelligence and the depth or intensity of experience that is possible? For example, if we could somehow untangle all the confounding variables introduced by differences in physiology, my intuition is that a bat or mouse should have a less robust or more “dim” experience of the same world as a human—but I don’t know that this is a reasonable intuition! Even thinking about this question with respect to animal companions, livestock, and creatures in the wild is really distressing, once I entertain the possibility that their experience of the world might be just as (or more) rich and exquisite as our own, in ways that we can’t begin to imagine. If that might be true, then I wonder whether the depths of potential misery that other creatures might experience are also just as exquisite (or more exquisite) than we can imagine, because we don’t know what it is like to be them.

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  3. The relationship between intelligence and intensity of experience is complicated because there are so many things that intelligence and intensity of experience could mean. Some of the descriptions of animal’s behavior in situations where a person would experience grief or joy look pretty darn intense.

    I think you might like this paper: “Animal Emotions: Exploring Passionate Natures: Current interdisciplinary research provides compelling evidence that many animals experience such emotions as joy, fear, love, despair, and grief—we are not alone,” Marc Bekoff
    BioScience, Volume 50, Issue 10, 1 October 2000, Pages 861–870, https://doi.org/10.1641/0006-3568(2000)050%5B0861:AEEPN%5D2.0.CO;2 .

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