There’s a certain expression a wet dog wears as it trots up to you, a kind of gleam in the eye that says, “I’m about to shake so vigorously that in a mere 4 seconds, 70 percent of the water in my fur will fly off of my coat and on to you.”
But the wet-dog shake, though it’s an annoyance to us, may be a survival technique to dogs. The water that sticks to a mammal’s fur can lower its body temperature, causing hypothermia, so it behooves wild animals to get rid of all that water as quickly and efficiently as possible.
To find out just how efficient the wet-dog method is, researchers from the Hu lab at Georgia Tech filmed 33 different wet zoo mammals from rats to kangaroos to lions and tigers and bears (oh yes) with high-speed cameras and analyzed the motion of their bodies, skin, and fur. Their research was first published back in 2010, but their latest study, published in the Journal of the Royal Society Interface, improves their mathematical model of the wet-dog shake and reveals how much force the furballs can generate. (The paper is not yet online; we will provide a link when it becomes available.)
One sleepy person can start a bout of contagious yawning that quickly spreads through a room. But a new study suggests the effect may not be limited to the room’s human inhabitants: Dogs can “catch” yawns from people, the study found—especially their owners, hinting that pooches may empathize with familiar people.
When listening to recordings of people yawning, 12 of the 29 dogs in the study yawned themselves. It made a big difference, however, whom they heard: The dogs yawned more than four times as much when they heard their owner yawn as when they heard as a stranger.
Specially trained sniffer dogs can smell something on the breath of lung cancer patients.
Dogs will sniff anything and everything, and can even tell identical twins apart by scent. And tumors, you may be surprised to learn, have their own very faint smells. To figure out how to diagnose internal cancers that are frequently overlooked until too late from just a breath sample, scientists have been working with dogs to see if these smells can be reliably differentiated from, say, the smell of breakfast, that last cigarette, or emphysema.
The latest diagnostic tool for oncology comes on four paws and is defined by its very effective nose. In a small study, Japanese researchers found that a dog could detect cases of colorectal cancer by sniffing patients’ breath or stool samples. Previous experiments have shown that dogs can sniff out cases of skin, lung, bladder, and breast cancers; researchers think the tumors give off chemical signals that the dog can detect in bodily substances.
The cancer expert in this case was an eight-year-old black Labrador named Marine who was trained to search for disease traces at the St. Sugar Cancer Sniffing Dog Training Center in Chiba, Japan. She must have been a good student. The research, published in the journal Gut, showed that she had a high success rate:
The Labrador retriever was at least 95 percent as accurate as colonoscopy when smelling breath samples, and 98 percent correct with stool samples, according to the study…. The dog’s sense of smell was especially effective in early-stage cancer, and could discern polyps from malignancies, which colonoscopy can’t. [Bloomberg]
Lead researcher Hideto Sonoda says it would be impractical to use dogs for routine bowel cancer screenings, but adds that further research into dogs’ diagnostic ability could lead to the development of an electronic nose.
Dr Sonoda told the BBC: “The specific cancer scent indeed exists, but the chemical compounds are not clear. Only the dog knows the true answer. It is therefore necessary to identify the cancer specific volatile organic compounds [smells] detected by dogs and to develop an early cancer detection sensor that can be substituted for canine scent judgement. To complete the sensor useful in clinical practice as a new diagnostic method is still expected to take some time.” [BBC]
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DISCOVER: 20 Things You Didn’t Know About… Dogs
Image: flickr / pmarkham
To a human living in North America about 9,400 years ago, dogs may have been both trusted friends and loyal protectors. But they were something else too: dinner.
A DNA analysis of an ancient dog’s recovered bone fragment reveal that dogs were already domesticated at this stage in North American history, and the fact that the bone bore evidence of passing through the human digestive tract reveals that our ancestors were willing to chow down on their canine companions.
The bone was recovered in ancient human fecal matter found in a southwestern Texas cave in the 1970s–but it wasn’t until recently that Samuel Belknap III, a University of Maine anthropology graduate student, found a bone within the ancient poo. The discovery was all the more welcome given that he wasn’t looking for dog bones in the first place.
“I didn’t start out looking for the oldest dog in the New World,” Belknap said. “I started out trying to understand human diet in southwest Texas. It so happens that this person who lived 9,400 years ago was eating dog.” [UMaine News]
Doggie separation anxiety–the whining, scratching, and general misbehaving that happens when some dogs are left home alone–is somehow linked to the dog’s general outlook on life, new research says. Coauthor Emily Blackwell explains that she wondered whether the behavior she’d observed during high school in her own anxiety-prone dog was normal.
“So many people think [separation-related behavior] is just something dogs do.” … They think the dog is angry the owner is leaving, say, and exacting its revenge on the owner’s slippers. [ScienceNOW].
For the study, published in Current Biology, the team investigated the link between this separation anxiety trait and a pessimistic attitude. To test pessimism, 24 dogs were trained to associate a full food bowl with one side of a room and an empty bowl with the opposite side.
The dogs learn quickly “if it’s on one side, to race over and nearly knock over the screen to get it,” says Blackwell. “If it’s on the other side, they look around and quite often give us a big sigh.” Some dogs amble over to check out the empty bowl; others just lie down. [ScienceNOW]
Hounds, pointers, and other dogs bred for their excellent abilities to pick up a scent tend to have longer snouts—but it’s not just that a bigger nose is a better one. Researchers have found that human domestication of dogs has shifted the structure and alignment of some dogs’ brains. And in those varieties with shorter snouts—which humans bred for other reasons, like appearance—the olfactory brain region rotated to a different part of their skull, leaving scientists to question whether we’ve crossed up their smelling abilities (and perhaps more).
Since the first wolf was domesticated an estimated 12,000 years ago, “selective breeding has produced a lot of [anatomical] variation, but probably the most dramatic is in terms of skull shape,” said study co-author Michael Valenzuela [National Geographic].
For this study, which appears in the open-access journal PLoS One, Valenzuela and colleagues examined the brains of 11 dog breeds and found great variation in the size and shape of their skulls. The breeds with shorter snouts had brains that rotated forward by as much as 15 degrees over the generations, the scientists say. That means that the olfactory lobe, as well as other parts of these dogs‘ brains, has shifted position and shape because humans guided their evolution through domestication.
Dog-fighting is a federal crime and a felony offense in every U.S. state, but it’s difficult to detect and stop. Officers rarely catch fighters in the act, and the industry, as a multimillion-dollar business, makes money not only from gambling on the violent and often fatal matches, but also from breeding and selling champion dogs.
The New York Times reports that some dogs sell for as high as $50,000 dollars. The American Society for the Prevention of Cruelty to Animals estimates that there could be tens of thousands of people involved in dog fighting in the United States.
So where does the genetics come in?
At some point in evolutionary history dogs diverged from wolves thanks to domestication by humans. But just where did dogs first become man’s best friend? Robert Wayne and his team have many years invested in answering the question, and their newest findings, published this week in Nature, suggest that the answer is the Middle East.
Researchers looked at gene segments from 912 dogs, from 85 breeds, and samples of 225 grey wolves, dog’s close cousins who they evolved from in prehistory, from 11 regions [USA Today]. Dogs and wolves that come from the Middle East, Wayne says, show the most genetic similarity. The researchers propose that dogs were first domesticated there, and then spread outward.
Dogs and wolves are closely related enough that they have interbred at various times, complicating the problem of unraveling dogs’ origin. Wayne’s team suggests that after the domestication of dogs in the Middle East, they interbred with wolves when they reached East Asia, which is how dogs and wolves there came to share some of their genetics.
Curvis Bickham spent eight months in prison for a triple-homicide because a police dog confused his scent with that of the killer. Now Bickham and others who spent months in jail after dogs linked their scents to evidence from crimes they did not commit are filing a lawsuit claiming Texas authorities falsely arrested and imprisoned them, their attorney said Tuesday [AP]. In a scent lineup, dogs sniff items found at a crime scene, and then sniff jars swabbed with the suspects’ scents and the scents of others not involved in the crime. When the dogs link crime scene and suspect, that evidence is often relied on heavily in court by the prosecution. Alaska, Florida, New York and Texas all use scent lineups to link suspects to crimes.
Dogs are used all the time to fight crime—from sniffing out bombs and drugs to locating dead bodies. However, scent lineups have critics barking. They say the lineups are poorly controlled, and argue that avoiding cross-contamination is basically impossible. The main target of the current lawsuit is Fort Bend County Deputy Keith Pikett—whose home-trained bloodhounds identified the suspects. A 2004 F.B.I. report warned that dog scent work “should not be used as primary evidence,” but only to corroborate other evidence. In several of the cases that were based on Deputy Pikett’s dogs, however, the scent lineups appear to have provided the primary evidence, even when contradictory evidence was readily available [The New York Times]. Deputy Pikett, by his own estimation, has conducted thousands of scent lineups.
The three men who filed the lawsuit against Deputy Pickett were all eventually set free after contradictory evidence proved their innocence. The Innocence Project of Texas, a legal defense organization … released a report last month that excoriated dog scent lineups as a “junk science injustice” [The New York Times]. Dog scent lineups bring to mind another high profile forensic science debate in Texas that many believe led to the execution of an innocent man. Now that the science behind dog scent lineups is coming under the same scrutiny, one can’t help but wonder if scent lineups might have led to a similar outcome.
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DISCOVER: Reasonable Doubt examines the fallibility of DNA evidence
Image: flickr / contadini