Courtesy Photo / Ned Rozell 
A dog’s nose is one of the wonders of the animal kingdom.

Courtesy Photo / Ned Rozell A dog’s nose is one of the wonders of the animal kingdom.

Alaska Science Forum: The world according to a dog’s nose

  • By Ned Rozell
  • Friday, June 3, 2022 3:36pm
  • News

When a Lab vacuums the ground with their nose and their tail moves like a helicopter blade, you know a grouse is about to fly. When the dog stops like a dragonfly, then runs off sniffing an invisible path, a snowshoe hare has crossed your trail.

All this entertainment is courtesy of that most sensitive appendage, a dog’s nose. It’s an instrument humans have not been able to duplicate. Search-and-rescue groups use dogs to find lost people, dead people, and people buried under earth and snow. Dogs have also been used to find seals on ice, gas leaks and the presence of gypsy moth egg sacks.

Lurking behind those textured, damp nostrils are sensitive membranes that allow a dog to distinguish smells—molecules of odor that emanate from every living or once-living thing—at least one thousand times better than humans.

A terrier mix sniffs at the ground in Juneau on a recent sunny day. A dog’s nose is an instrument humans have not been able to duplicate. (Ben Hohenstatt / Juneau Empire)

A terrier mix sniffs at the ground in Juneau on a recent sunny day. A dog’s nose is an instrument humans have not been able to duplicate. (Ben Hohenstatt / Juneau Empire)

A dog processes odoriferous molecules more readily because a dog has a much larger set of scent membranes within its nose, explained Robert Burton in his book, “The Language of Smell.” While humans have a pair of these “olfactory receptors,” each is about the size of a postage stamp in our noses. Dogs’ receptors can be as large as a handkerchief, depending on how big the dog is.

Dogs’ noses work much the way ours do: We inhale molecules of odor, which then dissolve in mucus. The dissolved odors are picked up by the olfactory receptors, located behind the spot where sunglasses rest on the nose. An organ called the olfactory bulb shunts the chemical messages straight to the part of the brain that deals with stored feelings and memories, bypassing the cerebral cortex, the main part of the brain. This short-circuit is one reason smells trigger strong emotions and memories that may have lain dormant for years.

With its larger olfactory membranes, a dog’s nose does amazing things. Researchers at Duke University found that a randomly selected fox terrier could after three weeks detect the scent of a fingerprint on a glass slide when compared to four clean slides. When the researchers placed the slides outside in the rain and dust, the dog was still able to pick out the slide with the fingerprint after 24 hours of weathering.

Dogs have fantastic tracking ability because humans leave a pretty good scent trail. Most researchers think the scent trails consists of “rafts,” tiny bits of skin cells that have an odor when mixed with sweat and fed upon by bacteria. Because the human body sheds about 50 million cells each minute, rafts fall from the body like a shower of confetti. Dogs quickly detect these rafts, as well as other scents that may not be apparent to the producer, including breath and sweat vapor. Each person’s scent trail is unique, and dogs are remarkably good at separating one person’s trail from another’s.

In an experiment performed a century ago, G. J. Romanes lined up 11 men behind him. He started walking, with each man walking precisely in his footsteps. After they walked 200 yards, the men dispersed, with five going to the right, six to the left. All the men hid. Another person released Romanes’ dog, which found Romanes almost instantly after hesitating slightly where the men separated.

Seventy years after Romanes’ study, H. Kalmus performed a similar test using identical twins. The twins must have had quite similar scents, Kalmus reported: “if the dog was given the scent of one twin, it would happily follow the other.” When both twins were used in the experiment, however, the dog was able to pick one from the other.

• Since the late 1970s, the University of Alaska Fairbanks’ Geophysical Institute has provided this column free in cooperation with the UAF research community. Ned Rozell is a science writer for the Geophysical Institute. A version of this column appeared in 1998.

More in News

(Juneau Empire file photo)
Aurora forecast for the week of April 15

These forecasts are courtesy of the University of Alaska Fairbanks’ Geophysical Institute… Continue reading

(Michael Penn / Juneau Empire file photo)
Police calls for Wednesday, April 17, 2024

This report contains public information from law enforcement and public safety agencies.

Newly elected tribal leaders are sworn in during the Central Council of the Tlingit and Haida Indian Tribes of Alaska’s 89th annual Tribal Assembly on Thursday at Elizabeth Peratrovich Hall. (Photo courtesy of the Central Council of the Tlingit and Haida Indian Tribes of Alaska)
New council leaders, citizen of year, emerging leader elected at 89th Tribal Assembly

Tlingit and Haida President Chalyee Éesh Richard Peterson elected unopposed to sixth two-year term.

A waterfront view of Marine Parking Garage with the windows of the Juneau Public Library visible on the top floor. “Welcome” signs in several languages greet ships on the dock pilings below. (Laurie Craig / For the Juneau Empire)
The story of the Marine Parking Garage: Saved by the library

After surviving lawsuit by Gold Rush-era persona, building is a modern landmark of art and function.

A troller plies the waters of Sitka Sound in 2023. (Photo by Max Graham)
Alaska Senate proposes $7.5 million aid package for struggling fish processors

The Alaska Senate has proposed a new aid package for the state’s… Continue reading

Current facilities operated by the private nonprofit Gastineau Human Services Corp. include a halfway house for just-released prisoners, a residential substance abuse treatment program and a 20-bed transitional living facility. (Gastineau Human Services Corp. photo)
Proposed 51-unit low-income, long-term housing project for people in recovery gets big boost from Assembly

Members vote 6-2 to declare intent to provide $2M in budget to help secure $9.5M more for project.

Members of the Alaska House of Representatives watch as votes are tallied on House Bill 50, the carbon storage legislation, on Wednesday. (James Brooks/Alaska Beacon)
Alaska House, seeking to boost oil and gas business, approves carbon storage bill

Story votes yes, Hannan votes no as governor-backed HB 50 sent to the state Senate for further work.

(Michael Penn / Juneau Empire file photo)
Police calls for Tuesday, April 16, 2024

This report contains public information from law enforcement and public safety agencies.

Most Read