♪ (narrator) To us, this is just a field.

But to this dog, it's a portal through time.

She can peer into the past, what happened an hour, even a week ago... thanks to this exquisite olfactory device.

Zinka is a search and rescue dog, a champion sniffer.

Today she's working with researchers from the University of California Berkeley.

[cute voice] Yes, she is.

She's wearing a GPS device and other sensors so they can figure out how she tracks smells so well, like from this hiker, because tracking smells isn't like following a dotted line on a map.

Odors don't spread out evenly.

They're all swirly, twisted around by air currents.

But Zinka's nose can make sense of that.

It's a precision instrument.

Like us, dogs can tell if smells are coming from the left or right because their nasal passages are completely divided.

But here's how Zinka totally outdoes us.

When she sniffs in, most of the air goes into her lungs.

But some of it splits off into a separate stream that goes into a special chamber called an olfactory recess.

Inside, there's an intricate maze of little passages.

Here's a researcher scan of what it looks like in cross section.

All those twists and turns create a huge surface area which hold more than half a billion sensory cells that feed information to the brain.

That's 15 times more than we have.

All of our sensory cells are in this little patch.

And we don't have a special chamber for smelling.

When Zinka exhales, the air is blasted out the sides through those slits, so she can take in a fresh sample each time.

First, she gets a sample, something the hiker has worn.

Then she hits the trail, sniffing about five times per second.

Zinka can pick up the tiny amounts of scent down to the molecules the hiker left behind that we would never notice.

She can easily tell her apart from other humans as she finds her way through the maze of trails... which leads her right to the hiker.

Good girl, Zinka.