Inside the extraordinary nose of a search-and-rescue dog

Meet Zinka, the rescue dog. Dogs are relentless smellers. Their noses can catch a scent from a mile away… …five times farther than we can. These pooches can follow a smell for hundreds of miles which allows them to save lost people or catch bad guys. There are millions of reasons why the canine sense of smell is better than ours and we’re going to
tackle all of them in the next three minutes. Ready! Set! Sniff! Let’s start by hopping
inside a dog’s nose Weeee! One key to a canine’s super snout is its long and intricate nasal cavity. It’s like a little cathedral inside your
nose full of these bones. Allow me to introduce Lucia Jacobs. She’s a neuroscientist at the
University of California Berkeley, and she’s absolutely obsessed
with how dog noses work. There’s all these
intricate bony plates that are bending into what are called turbinates which control how air moves through the nose. Turbinates create a labyrinth of folds and corridors that filter odors toward different parts of a dog’s nose. T-Bone steak lands here, the neighbor’s cat lands there. At the same time, dogs seem to smell in stereo. Their two nostrils sniff at
different rates, so they can tell if your gym socks are to the left or right. This leads to some pretty funky behavior… …like circling. Jacobs: Olfactory navigators circle when they’ve got the scent
but they don’t know is it going off in a different direction. In our last episode of ScienceScope
we showed you how an odor isn’t a uniform cloud. Its shape is scraggly and wild, with portions that are stretched like taffy. Sitting inside an odor plume doesn’t tell you much. You’re surrounded by a jumbled mess. But traveling along the edge of
an odor offers context and direction. That’s why dogs circle. They’re looking for the edge. So, what they do is they do is a circle to pick up where is it strongest and then they’ll start exploring in that direction. Remember those millions of reasons I promised? A dog has 300 million smell sensors which are also known as olfactory receptors inside of its nose. Humans only have five million. Womp womp. Many think dogs are great sniffers because of all of those smell sensors. But Jacobs disagrees. Her theory is the
strength of an animal’s sense of smell depends on the size of its habitat. Her idea starts with the olfactory bulb, a relay station just above the nose that sends smell information
deeper into the brain. In carnivores, like wolves and coyotes and foxes if you look at the size of their home range, the olfactory bulb scales with
the size of their home range. The modern human, in contrast,
relies on smells for short distances, which may explain why human olfactory systems are smaller. Wait… Do you smell that? It smells like cookies in the break room. I’ll be right back. Oh man, that’s good. Oh! Where were we? But Jacobs believes, deep down,
all animals react to smells the same way Her lab is testing this theory
in a cornucopia of species dogs, humans, hermit crabs, two types of cockroaches and the leopard slug. They all move in the same way.
They all track odors in the same way. So we think there’s got to be
a common algorithm that they’re all using. Jacobs is part of a nationwide team trying to code those smell algorithms into robots. That’s all for now. I’m Nsikan Akpan, and this is ScienceScope
from the PBS NewsHour.

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