Dogs' Residual Ancestral Traits

"The dog rhinarium (naked and often moist skin on the nose-tip) is prominent and richly innervated, suggesting a sensory function. Compared to nose-tips of herbivorous artio- and perissodactyla, carnivoran rhinaria are considerably colder. We hypothesized that this coldness makes the dog rhinarium particularly sensitive to radiating heat. We trained three dogs to distinguish between two distant objects based on radiating heat; the neutral object was about ambient temperature, the warm object was about the same surface temperature as a furry mammal. In addition, we employed functional magnetic resonance imaging on 13 awake dogs, comparing the responses to heat stimuli of about the same temperatures as in the behavioural experiment. The warm stimulus elicited increased neural response in the left somatosensory association cortex. Our results demonstrate a hitherto undiscovered sensory modality in a carnivoran species."
Abstract, Dogs can sense weak thermal radiation, Scientific Reports

Thermograph of a dog in the shade at 27 °C ambient temperature. The colour scale on the right is in °C and can be used to read out approximate temperatures. Note the warm tongue and the cold rhinarium (hairless nose tip). Scale bar: 50 mm.

"Dogs are able to sense the thermal radiation coming from warm bodies or weak thermal radiation and they can also direct their behaviour according to this signal."
"We tested whether we can find an area in the brain that shows higher activity if they are exposed to a warmer than to a colder object."
Anna Balint, study lead author

"It is possible that other [carnivores] possess a similar infrared sense and that adds a new chapter to the story of prey-predator relationships."
"Predator hunting strategies have to be re-evaluated and the biology of prey animals has to be revisited with body heat sensing predators in mind."
Ronald Kroger, sensory scientist, Lund University

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According to newly-published research in Scientific Reports, a journal published by Nature Research, scientists at Sweden's Lund University in collaboration with Hungary's Eotvos Lorand University found the naked, wet skin surface at the tip of a dog's nose -- full of nerve endings -- has the capacity to act as an infrared sensor.

Brain scans indicated increased brain activity when dogs were shown objects that were warmer than their surroundings. Golden retrievers and Border collies were among the dog breeds tested in this study. To test their theory that dogs' noses have not only an olfactory purpose, but also a capability to sense the presence of warm objects when prey is near, the researchers trained three pet dogs to choose between a warm and an ambient-temperature object.

Where the dogs were unable to see or smell the difference between the two placed 1.6 meters' distant from them, after training the dogs were tested in double-blind experiments which led to all three dogs detecting the objects that emitted weak thermal radiation. The researchers followed up by scanning the brains of 13 pet dogs of different breeds in a functional magnetic resonance imaging (MRI) scanner.

Within the scanner the dogs were presented with objects emitting neutral or weak thermal radiation. It was found that the left somatosensory cortex in dogs' brains delivering inputs from the nose, turned out to be more responsive to the warm thermal stimulus than to the neutral one. Which led the scientists to identify a cluster of 14 voxels (JD pixels) in the region of the dogs' left hemispheres, while no such clusters were found in the right, and none in any part of the dogs' brains in response to the neutral stimulus.

The two experiments in tandem demonstrated that dogs, like vampire bats, are capable of sensing weak hot spots; that a specific brain region becomes activated by this infrared radiation. The scientists feel that dogs likely inherited this trait from their ancestral gray wolf connection who may have used it during hunts to sniff out warm bodies.

"The study is consistent with other research that describes the combined dog nose and brain as a sophisticated platform for processing a broad range of signals."
"[It is doubtful however], that the dog rhinarium can distinguish patterns of hot and cold objects at a distance [suggesting dogs’ thermal detection skills may not be useful for long distance hunting. “[T]hat needs further study.”
Gary Settles, emeritus professor of mechanical engineering, Pennsylvania State University, University Park

An infrared photo of a golden retriever in a functional magnetic resonance imaging scanner reveals the cold temperature of a dog’s nose versus its glowing, warm body.

Anna Bálint

Conservation, Inuit Tradition, Climate Change

THE CANADIAN PRESS/Jonathan Hayward

"They had to sit tight. It was pretty scary. They didn't sleep and they were out there for a while."
"It looks like it was a mother [polar bear] and a cub. The mother and the cub were killed."
"[The hunters] killed at least one more. There were multiple other bears in the area that were attracted by blood and scent."
Rob Hedley, administrator, hamlet of Naujaat, Nunavut

"I can't even describe the pain we're feeling right now."
"Those [bears] could have been caught if we didn't have these laws from the government."
"[Bears] are in our land and they are very, very dangerous. I just want Inuit to kill all the bears they see."
"It was a heavy burden to share the sad news with our community."
Helena Malliki, Naujaat, Nunavut

"The past few years, sightings and encounters have been rising. We're at a different level now."
"The guys I've been talking to say the bear population is at a level where it's safe to not have a quota."
Gordy Kidlapik, Rankin Inlet

"The seal harvest dropped dramatically [once the European ban on seal fur destroyed the market]."
"Bears start to move ashore [once the sea ice cover is lost]. Once all those bears are on shore, the likelihood of them coming into conflict with people increases."
"The ecosystem is changing. People in polar bear habitat have to look at changing some of their behaviour."
Andrew Derocher, polar bear biologist, University of Alberta

A polar bear walks over sea ice floating in the Victoria Strait in the Canadian Arctic Archipelago. RCMP say a hunter died after a polar bear attack near Naujaat, Nunavut. (David Goldman/Canadian Press)

Inuit communities in Canada's far north are resentful of interference by the federal and territorial governments that limits their hunting of polar bears. Quotas limiting the numbers of polar bears to be killed in each of the territorial regions act to constrain Inuit from thinning out the bear population, they contend. The result, they charge, is an overabundance of the powerful beasts who then threaten the existence of the people of the north. Inuit say they are exposed to greater numbers of 'interactions' with bears on the land than ever before.

In early July a man from Arviat was enjoying a family outing on an island close by the community with his children. A polar bear suddenly appeared. The 31-year-old Inuit man shouted to his children to run as he placed himself in harm's way to protect his children. He was killed, and the children survived, having run to safety. More recently, two Inuit hunters spent three days huddling alongside the body of a third hunter, killed by a polar bear. Four bears circled their camp, as the hunters hoped for rescue.

The bitter response from Inuit at the news that another of their community members has been killed by a rampaging bear, is that southern interference by people who have no idea of the dangers northern people can be exposed to, are the architects of legislation that complicate their lives in the interests of conserving bears, even while their habitat is being impacted by climate change. The stranded men had left from Naujaat on the northern shore of Hudson Bay on August 21, planning to hunt for narwhal and caribou.

Expectations were that they would be returning last Thursday; when the three hunters hadn't returned by Sunday, police were notified. The following day federal, territorial and local teams set out to investigate, knowing approximately where the hunters had been headed. Heavy sea ice conditions blocked the search boats, so the Coast Guard icebreaker Louis St.Laurent went into action, its helicopter discovering the hunters early the next day, 100 kilometres east of Naujaat.

The two hunters who had remained by their dead companion had been injured, but not seriously. Polar bear biologist, Dr. Derocher, commenting on the situation, pointed out that the quotas being criticized for hampering the Inuit from thinning out the presence of polar bears, ensuring the safety of the community, are set in Nunavut but only after consultation with hunters. Lacking careful management of the bears, the likelihood of a backlash from the international community, he pointed out, would have a deleterious effect on the communities' well-being.

A mother polar bear and her cub near Churchill, Man. A hunter from Naujaat, Nunavut, was killed after a polar bear and cub attacked him and his two friends on Thursday. (Elisha Dacey/CBC)

The European Union would possibly spearhead a ban on exports of polar bear products from Canada, essentially destroying an important income source for those Inuit communities. Inuit would end up killing even fewer bears, just as occurred when the ban on seal fur destroyed that market. Local hunters, he pointed out, had failed to take their allotted one hundred bears last year, despite the complaints of insecurity now being cited by community members in the wake of those two deadly polar bear attacks.

He also pointed out that the Foxe Basin bear population around Naujaat has seen the loss of some 30 days of sea ice seasonally over the last number of decades. Once the sea ice is unstable, the bears that usually hunt seals and other polar wildlife from the ice, abandon their uneasy perches for land. And this is when the intersection of bear and man becomes acute. A problem, however, attributed now to climate change propelling the bears into areas where that interaction becomes more common, with its potential for unfortunate occurrences.

The last death has been attributed to an interaction between the hunter, a mother bear and her cub. Bears are known to be acutely protective and angrily reactive to anything they perceive to be threatening to their cubs. This is elementary, and common knowledge. That a seasoned hunter would come to grief in this type of scenario is indeed inexplicable. The mother and cub were killed at the scene of the unfortunate encounter, along with another bear.

The World Within In Us

"We don't have a good grasp of what these seasonally varying microbes even do."
"We have to think of ourselves as these composite organisms, with microbial and human parts."
"An abrupt change in diet will lead to an abrupt change in the gut microbiome, on the order of a day or two."
"We're in some weird, perturbed state where many of the microbes we co-evolved with are not equipped to flourish."
Justin Sonnenburg, microbiologist, Stanford University, California

Hadza man eating honeycomb and larvae from a beehive.

Matthieu Paley/National Geographic

If we are what we eat is true, what we eat significantly affects our elimination patterns of what we intake. Which, at one time in human evolution consisted in the whole of whatever a hunter-gatherer society could bring to the table, as it were. That was a function reflective of the seasons primarily. Whereas at the present time in any advanced society where food has been regularized in the sense that it only resembles now what it was like in its original, natural whole-food state for the most part.

Even fruits and vegetables which can be untouched from the ground to the table, have undergone vast changes from their original state as what is now quaintly termed 'heritage' types have given way to cultivars bred carefully for their taste, shape, abundance, and ability to withstand shipment across continents have also changed. Not quite to the extent that whole foods undergoing processing and supplemental additions have, transforming them entirely into another sub-food category.

All of these things affect the gut biome that we acquire as a reflection of what it is we eat. Scientists interested in such matters since they impact on human health and longevity, have studied an ethnic minority living in Tanzania, comprised of only 1,300 people. What makes this small group unique is that they continue to live as their ancestors did, sustaining themselves with hunting, scavenging for berries, honey and a handful of wild foods.

This was how all human groups once fed themselves. As a result of their isolation and their way of life, they have attracted the attention of researchers who study intestinal microbiome, the life of our intestines, through the bacteria inhabiting them and ultimately fashioning how we excrete waste. Researchers detected an annual rhythm in the gut of this group where some bacterial species absent themselves for parts of the year, and then make their entrance once again, as the Hazda people regularly alter their diets in synchronicity with the seasons.

Thousands of species of bacteria inhabit the intestines of every human being; an estimated 30 trillion bacteria teeming in our guts, every one of us. The idea was in this study to compare the microbiome of hunter-gathers in as close to the original state of early human development with those of people living in various 'advanced' societies, enabling scientists to understand the manner in which diets influence the composition of gut bacteria.

Stool samples were collected from the Hadza four times over the course of a year, a trial that began in 2013 when a visiting research fellow at King's College London, initiated work with Tanzania's National Institute for Medical Research. An analysis was taken of some of the samples. The study, published in the journal Science, laid out the manner in which Dr. Sonnenburg and his colleagues detected sharp fluctuations in the composition of the Hadza gut bacteria. Recognizing some species to be more evident in one season, not another while some absented themselves altogether.

In the course of a year, the Hadza gather fruits from baobab trees, while in the dry season tubers are eaten along with plenty of meat since dry seasons favour hunting. Foraging for berries and harvest honey from beehives takes place primarily in the wet season when hunting is less gainful. The Hadza microbiome was compared with those of people living in 17 other societies, inclusive of American urbanites and Amazon rain forest Yanomamo villagers, another isolated group.

The goal was to try to understand how it might be possible that gut microbes linked to industrialization affect the health of people in those societies. The Hadza microbiome representing those living in traditional societies, least akin to those living in industrialized societies, far from the natural world and its rhythms where the availability of certain foodstuffs is dictated by the seasons. Whereas in materially developed countries food tends to be shipped far and wide.

Dr. Sonnenburg speculates that consuming the same foods year-round led to the loss of food seasonality and the disappearance of ancestral bacterial species. Which in turn have given impetus to a new set of gut microbes over those that fed on plant fibers.

Hadza women cook tubers they've foraged throughout the day. Compared to the men, who spend their day hunting game, the women have more gut bacteria for breaking down fibrous veggies.

Image: Alyssa Crittenden