Dogs use their noses for everything from sniffing out criminals to smelling cancer cells. But why is that, and what can humans do to improve their own sense of smell?
That’s the mystery Alexandra Horowitz, a professor of English and psychology at Barnard College, attempts to solve in her new book Being a Dog: Following the Dog Into a World of Smell. Horowitz, who also runs the Dog Cognition Lab at Barnard, became fascinated by Fido while completing her dissertation at the University of California, San Diego in 2000. She wanted to study the minds of animals while they were engaged in natural behaviors like play and decided dogs were the perfect subject—they’ve been her focus ever since.
Some canine actions, like peeing on fire hydrants or scratching the ground after pooping, are meant to protect their turf and send messages to other dogs—Horowitz calls this marking “pee-mail.”
Most activities in a dog’s daily life, however, revolve around their noses—they wag their tails to spread their scent, and even assign an attractive smell to their owners, which is why they lick them.
“They live in a sensory parallel universe of odors which is as rich as our world of light and sight,” Horowitz said. “We’ve forgotten to attend to it.”
Indeed, while dogs are considered macrosmatic, with a highly developed sense of smell, humans are microsmatic, with a reduced olfactory sense. As Horowitz writes, human noses are “children’s block towers” compared to dog noses.
This is partly because human societal norms don’t encourage sniffing.
“It’s not culturally permissible in Western culture to stick our noses in things or other people,” Horowitz said. “We’re in a deodorization moment in time.”
That doesn’t mean humans don’t have the potential to be great smellers, however—they can easily remember certain odors if a certain memory conjures them up.
“Humans have amazing smell memories—they’re so intimately tied to emotion,” Horowitz said. “Most people find it delightful, but we don’t do it intentionally.”
For an example of how smell memory works, look no further than the Pixar classic Ratatouille. When dour food critic Anton Ego takes a whiff (and then a bite) of chef Remy’s titular dish, he is instantly transported back to his childhood, and the happy memory of his mother making the vegetable stew:
Following Ego’s example isn’t difficult, according to Horowitz: rather than mindlessly inhaling, she said people should treat smell as an integral sense, like perfumers and sommeliers do.
“It’s really easy to improve an underused sense,” she said. “Just bring things to your nose and intentionally sniff.”
To help improve her own olfactory capabilities, Horowitz went on a “smell tour” of New York City as part of her research. She admits that going through the city alone smelling is a little embarrassing, so she recommends bringing some “conspirators” along.
“It’s not OK for humans to sniff a tree, but when you do it together it goes from awkward to thrilling,” Horowitz said.
The most common smells in New York City, as detailed in Being a Dog, include garbage wafting from the sidewalks, steam and food scents from meat trucks and peanut sellers and an “ozone” odor that’s common when moving from subways to ground level. As the weather gets colder, the smell of “de-mothballed” sweaters also becomes more common.
Even the most practiced human nose can’t compete with a dog nose, however: police dogs in France have been trained to nasally detect a suspect’s body odor at crime scenes—and this testimony may one day be admissible in court.
Canine clinicians have even been able sniff out cancer: in several studies, dogs were able to distinguish the urine of cancer patients from healthy urine because they were trained to smell the plasma in the cancer cells.
“There are hundreds of components to the odor, but dogs are extremely reliable,” Horowitz said. “They can identify it in the early stages.”
Human noses may not be able to fight crime and cancer like their dog counterparts, but Horowitz concluded that they still have enormous value.
“We have an incredibly good nose ourselves, but we don’t pay attention to it,” she said. “We should use our noses to enrich our understanding of each other.”
