Dogs and Smell

If you ask someone what animal has the best sense of smell, chances are that most people will answer “Dogs”. Not a bad answer, though not quite right. At least two others are better.

 

 

Dogs have an amazing sense of smell. That's why we use dogs to track and find people who are lost, buried in avalanches, trapped in earthquake- or bomb-damaged buildings. We use dogs to sniff out illegal drugs, explosives, buried landmines, soil contaminants, animals of specific endangered species, black truffles, and even diseases. They couldn’t do it without their remarkable ability to smell. But what’s also significant is that dogs are so willing to be trained for these tasks. Some other candidates with great noses are less convenient and obliging. More on that, later.

Why are dogs are better at smelling than human?

·         Humans have 5-6 million smell receptor cells in our noses; dogs 100-300 million.

·         The area of the brain devoted to processing smells is 40 times larger in dogs than in humans. 

·         Dogs have a special organ — the “Jacobson’s Organ” devoted to processing smells. We don’t. 

·         As humans breathe in, we get new smells. As we breathe out, nothing. As dogs breathe out, their breath causes some turbulence which pulls new scents into the smelling area of their nostrils. 

·         Dogs can distinguish whether smells are coming from their left or right nostril. The difference of smell between the two nostrils lets them know the direction a smell is coming from. 

Professor Alexandra Horowitz, head of the Dog Cognition Lab at Columbia University summarizes a dog’s ability to smell: “while we might notice if our coffee has had a teaspoon of sugar added to it, a dog could detect a teaspoon of sugar in a million gallons of water, or two Olympic-sized pools worth.” Alexandra Horowitz has written a number of fascinating books about dog cognition, most recently The Year of the Puppy, and  Our Dogs, Ourselves.

Dogs can identify the intensity of a smell with incredible sensitivity. By smelling 5 footprints they know which are less intense and therefore older. From this they know which direction the person was walking.

 Scientists also believe that this is how dogs know when to expect owners back from work. If the owner has a regular routine and returns, say, 9 hours after leaving, the dog knows that when the owner’s smell has dissipated to a 9-hour-old level, it’s time for their return. Ingeniously, this hypothesis was tested by quietly reinforcing the owner’s scent during the day, by introducing clothing worn by the owner. Dogs who habitually waited at the front door at the right time, were fooled.

For dog owners it’s important to understand that dogs’ sense of the world is primarily through smell, not sight, as ours is. Your dog will be happier and better adjusted if you allow it to spend a lot of walking time following the interesting smells which are all around. And which you are unaware of. When we meet people, we naturally look at them to get a sense of who they are. Dogs smell each other to get that. Females tend to smell the front end of other dogs; males the back ends. By smelling they can tell the age, gender and health of the other dog. And more – like sexual attractiveness.  But while we need the person present to see that information, dogs can smell that information by sniffing where the dog has been. When dogs sniff a tree, hydrant or telephone pole, they’re identifying who has been there. And when they pee on it themselves, they’re leaving a message to say “I was here”.

By the way, our vision is not just better than dogs’ — it’s better than most of the animal world. Eagles can see more acutely than we can (“eagle eyes” is an apt expression), but few others even come close.

So what animals out-smell dogs? In hindsight it’s not surprising. Elephants’ noses are astonishing, not just for being long, but for being sensitive.

Elephants have been known to smell water from a distance of 20 km. They were tested for their ability to smell after it was noticed that they avoided land mines in Angola. Elephants can smell the difference between people from two Kenyan tribes: the Masai, who traditionally hunt elephants and the Kamba, who don’t. Elephants have been tested on their ability to tell, by smell, the quantity of sunflower seeds in a bucket with a perforated lid. The elephants consistently choose the fuller container.

In a really interesting experiment, described by Ed Yonge in his fascinating book An Immense World, scientists tested the ability of elephants to tell the identity of other elephants by the smell of their urine. The scientists would follow a herd of elephants and wait for one of them to pee. Then they would scoop up the pee-soaked earth, guess where the herd was headed, and dump that earth in the expected path. When the elephants reached that area, they would smell the pee-soaked earth. Those elephants who were walking ahead of the donor of the specimen were clearly confused by it. It was obvious that they knew whose pee they were smelling, but that individual was behind them, so couldn’t have just peed in front of them.

The other animal that can out-smell a dog is a bear. There are lots of stories about bears being able to smell animal carcasses from huge distances (some say up to 32 km), and male polar bears have been known to trek 100 miles (160 km) following the scent of a sexually receptive female.

But for very practical reasons we do prefer using dogs to help us with smell-related tasks, rather than elephants or bears.

 

 

 

 

 

 

 

 

Exploring Haida Gwaii

Sci/Why's peripatetic correspondent Margriet Ruurs sends us another report from a fascinating part of the world - this time from Haida Gwaii, on the western edge of Canada. -CE

By Margriet Ruurs

Haida Gwaii – the very name conjures up images of windblown spruce clinging to rocks surrounded by foamy waves, not unlike an Emily Carr painting. The archipelago stretches along the northern BC coast almost to Alaska. You can reach it by ferry from Prince Rupert or fly in from Vancouver.

We flew into Sandspit, a tiny town on the northeast shore of huge Moresby Island. We wanted to visit the very southern tip, which is in a National Park called Gwaii Haanas. Basically, the only way to reach this remote region is by a Zodiac (inflatable boat) tour offered by a local wilderness company called Moresby Explorers. We studied our options, counted our coins and decided to splurge on a four-day trip with a photography theme.

Bryan, our guide and skipper, picked us up and also five other guests with whom we would spend the next four days on a Zodiac. We drove from Sandspit across a ridge of Moresby Island, on dirt logging roads, to Moresby Landing where we were outfitted with bibbed rain pants, large rain jackets and gumboots. We’d live in these for the next few days. We wore undershirts, a sweater, a fleece jacket topped by our own rain jackets and then the provided rain gear over top. This meant we could only wobble like astronauts in space suits.

Of course we had prepared ourselves for four days of driving rain, grey skies and grey waves. Fortunately, we were lucky and only ended up with a half day of rain and three-and-a-half days of blue sky and sun and/or cloudy but dry weather. Considering that Gwaii Haanas averages rain for about 230 days a year, we were lucky.

We had not even left the Landing when I spotted the first black bear browsing on the intertidal beach. The island’s bears have evolved to have much longer snouts than the mountain bears we are used to seeing on the mainland. Like the Galapagos, even the same species of animals have made adaptations to different local environments resulting in, among others, a different subspecies of stickleback fish in every lake. At least 39 distinct subspecies of plants and animals evolved in the archipelago, including seven mammals, three birds and fifteen species of the stickleback fish that are found nowhere else in the world.

We cruised across inlets and around Louise Island to spend the first night at Moresby Float Camp, a guest house anchored in a secluded fjord. The blue skies reflected in mirror-calm green waters. We docked and were welcomed by two young women who cooked for us, offering us tasty appetizers, tea, coffee and hot chocolate. They even had a fireplace, giving us much needed warmth to warm our chilled hands and feet. After a great dinner of bbq salmon, salad, veggies and rice we fell asleep in no time.

The next morning we bundled up again. This became a ritual: two or three layers of warm clothes, thick socks and gloves. Then our own outer gear, the provided rain pants tucked into the gumboots and the rainjacket over top of everything else. By the time you can’t bend down anymore, you still have to manoeuvre into a lifejacket and into the waiting Zodiac. We’d pull a warm hat and scarf over nose, mouth and face and then we were ready to zoom across Hecate Strait to our next destination.

On our way by Zodiac to the most southern tip of Gwaii Haanas, we visited ancient village sites and remnants of totem poles in several locations: Skedans, Tanu, S’qang Gwaii, Rose Harbour and more. Each site has its own intrigue and charm. Skedans is a village site with house remnants and totem poles, but not as many as in the most southern tip S’qang Gwaii. Here, a mystical and misty atmosphere enhances the site where old spirits dwell and history is tangible. The bleached and weathered totems lean against moss covered house beams. The beach still tells stories of canoe runs between rocks, where the “Vikings of the Pacific” showed their power by rowing their long boats far east, north and south, taking slaves as they encountered other nations.

I was intrigued to learn that a Haida Chief could marry a slave woman, thus making the former slave the most powerful matriarch of the clan. In this matriarchal society, men do as the leading woman dictates and children are part of their mother’s lineage.

I also learned about different totem poles: the shortest one were usually house poles, depicting the family’s clan and history. Tall plain poles with rings are potlatch poles, showing how many potlatches, or celebrations, have been held. Some poles are a memorial for a particular person, sharing his life story, while yet others have a hollowed-out square opening at the top housing a bentwood box of bones: a burial pole. Their silent stories are impressive and pay tribute to a society that lived here long before “contact” – as the period after the arrival of European explorers’ ships is called.

Houses were large, sometimes dug down to allow more space. Immense ceiling beams were held up by corner posts and closed by cedar walls. Now, all that remains is rounded beams covered in soft green moss, often with a new cedar tree growing on each corner as the trees reseeded. Slowly and silently, history is swallowed up by the rainforest. The Haida people have chosen to let their history return to the earth, as it always has, rather than have Parks Canada follow their usual mandate of preserving history.

We were most impressed by the Watchmen. This ancient term refers to Haida who spend the summer in each historic location. They are provided with a small house with a wood stove and basic comforts. Here they work for the summer, hosting visitors. They are extremely well spoken, gracious hosts with a wealth of knowledge about their people. Each host told us amazing stories. Haida Gwaii is made up of stories and the oral history seems alive and well. We heard stories of how people first came to populate the earth when Raven found a clamshell full of little people on Rose Spit. He pried open the shell and the people spilled out. Raven also brought light to the world.

Bear married a woman who gave birth to bear cubs, and in return he gave hunting powers to humans. There are many tales of supernatural beings in this land. Mostly, these are people wearing animal cloaks. Eagle, Raven, Whale, Bear – they all have specific powers and fascinating stories. Haida also strongly believe in reincarnation.

One of the men who told stories, told us of the impressive oral history. “When I was about 10 years old,” he said, “my uncle called me into his house and told me a two-hour story. The next night I had to come back and tell the story back to him without embellishing, best as I could.”

This repeated night after night until he had memorized much of his own history. The tradition continues today as he tells his daughter the ancient tales and makes her tell them back to him.

We learned to chew spruce tips and licorice root. Even ate herring roe on kelp. We saw many, many eagles. A few glimpses of whales as well as two bears.

One overnight was spent in Rose Harbour, an old whaling station. Much debris, buildings and rusty tools remind one of an era when people caught and processed whales for oil. I found it a sad place to be. The lone woman who lives here offers a guest house and meals to Moresby Explorers. We ate greens from her immense garden and freshly caught ling cod. In the morning she ground grains on her converted exercise bike to make us pancakes with rhubarb sauce from the garden. An outhouse and wood-heated shower made it into a rustic adventure.

All photos by Margriet and Kees Ruurs.