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.
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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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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]
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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]
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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.
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Investigators are now swabbing dog cheeks. A dog DNA database–similar to the one the FBI keeps for criminals–may help to deter dog-fighting.
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?
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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.
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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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Image: flickr / contadini
It may not come as much of a surprise to dog-owners, but it seems that dogs and babies share similar logical abilities, as shown by a study published in Science.
Experimenters started out with a classic logic experiment, which goes like this: researchers hide a toy in location “A” multiple times while looking at a 10-month-old baby and talking to him (“Look, I have this nice ball!”). When asked to find the toy, the baby always goes to location “A.” The experimenter then hides the toy at location “B,” again while interacting with the baby. But this time, when asked to find the toy, the baby continues to search for it at location “A.” The findings hold, even when a team changes experimenters midtest. Researchers believe that infants make this error because they believe the adults have taught them something fundamental about the world (i.e., “Your toy will always be at location ‘A’”) [ScienceNow].
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The remarkable diversity among dogs‘ coats–from the shaggy fur of a sheepdog to the sleek coat of a beagle, and everything in between–comes down to a mere three genes, according to a new report published in Science. The broad genetic study determined that one gene controls hair length and softness, another determines whether the hair is straight or curly, and a third controls the pattern in which hair grows, so that dogs with a particular version have wiry hair and moustaches and long facial details known to breeders as “furnishings”…. The combinations in which these genes are inherited then determine a dog’s overall look [The Times].
To reach these conclusions, the researchers first looked at the genetic differences within single breeds that have more than one coat type. Purebred dogs are particularly suited for this kind of study, Dr. Ostrander said, because they have been selectively bred to segregate traits — there are long- and short-haired dachshunds, for example [The New York Times]. By analyzing the genomes of two dachshunds with different types of coats, the researchers were able to determine which gene was linked to the variation in hair length. Similar studies revealed the other two genes.
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Scientists trying to determine where dogs were first domesticated have been sent back to the drawing board by a new study. Back in 2002, researchers sampled DNA from dogs around the world, and determined that dogs in East Asia had the most genetic diversity, suggesting that the species originated there and that dogs in that region have had the longest time to evolve. But the new study suggests that those earlier results were skewed, because DNA sampling of African street dogs has revealed equal genetic diversity.
The earlier findings may have been thrown off because the large-scale study included both purebred dogs, whose evolution has been closely guided by human hands, and street dogs, who have bred more autonomously and randomly, and who therefore show more genetic diversity. But the 2002 researchers drew DNA from different types of dogs in different regions. Says Adam Boyko, lead researcher of the new study: “I think it means that the conclusion that was drawn before might have been premature. It’s a consequence of having a lot of street dogs from East Asia that were sampled, compared to elsewhere” [BBC News].
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Why does a wiener dog look like a wiener, with its body poised on such short, stubby legs? Researchers say they’ve discovered the answer in a single genetic mutation that’s found in dachshunds, corgis, basset hounds, and other short-legged dog breeds. Study coauthor Heidi Parker says this gene may turn on growth mechanisms at the wrong time during foetal development, stunting the growth of long bones in the leg and making them curvy. The trait affects only the legs, unlike the small-all-over effect seen in miniature or toy breeds, such as poodles [Reuters].
The mutation popped up sometime after modern dogs diverged from wolves, researchers say, and it’s a dominant gene–meaning that a dog with only one copy of the gene will show obvious signs of it. Having joined the genetic repertoire of dogs, the gene was available for selection by dog breeders whenever they wanted to develop a downsized breed. The basset hound, for example, was bred for its short legs so people on horseback could keep up with it during hunting, Dr. Parker said [The New York Times].
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Contrary to what scientists previously thought, it’s not only the power of a dog’s muscles that limits how fast the animal can accelerate; instead, it’s the need to keep those front paws on the ground and avoid doing a backflip. Although animals clearly don’t have wheels, the authors have branded this potential imbalance a quadrupedal “wheelie,” according to a study (pdf) published in the journal Biology Letters.
The ability to gain speed quickly is crucial for survival, but there’s a limit as to how rapidly an animal can accelerate. Researchers wondered whether the “wheelie” problem experienced by cars during a drag race could be a factor in four-legged animals’ ability to speed up. They came up with a simple mathematical model… to see how fast a quadruped could accelerate without tipping over backward. The model predicts that the longer the back is in relation to the legs, the less likely a dog is to flip over and the faster it can accelerate. Then the researchers tested the model by going down to the local track, London’s Walthamstow Stadium, and video-recording individual greyhounds as they burst out of the gate in time trials. The acceleration approached–but never exceeded–the limit predicted by the model [Science NOW]. That means that at low speeds, it’s the ability to keep his front end from pitching up that determines a dog’s maximum acceleration.
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Thousands of years ago a few bold wolves moved into a human encampment, and human lives have been richer ever since. But a new study shows that domesticated dogs gave something back to their wild cousins. A genetic analysis has revealed that the dark black coats common among wolves living in North America arose through wolves mating with dogs, who already had dark fur.
The finding presents a rare instance in which a genetic mutation from a domesticated animal has benefited wild animals by enriching their “genetic legacy.” … Because black wolves are more common in forested areas than on the tundra, the researchers concluded that melanism — the pigmentation that resulted from the mutation — must give those animals an adaptive advantage [The New York Times]. But what that advantage may be remains something of a mystery.
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A Florida couple has just received a genetic copy of their beloved and deceased golden Labrador Sir Lancelot, naming the three-month-old puppy Lancelot Encore. The couple paid $155,000 for one of the first commercially cloned dogs in the world, and say the money was well spent. “He was a wonderful dog,” said Nina Otto, 66. “Money wasn’t an object. We just wanted our wonderful, loving dog back” [ABC News]. The project was masterminded by the California biotech company BioArts.
Lancelot Encore joins a handful of other dogs cloned either commercially or as a proof of concept, and the latest success seems to indicate that researchers have thoroughly overcome the scientific barriers to cloning man’s best friend. Canines are considered one of the more difficult mammals to clone because of their reproductive cycle that includes difficult-to-predict ovulations [Reuters]. Now the fate of the fledging pet cloning industry is largely dependent on whether dog lovers think that clones are worth the high price tag. However, just yesterday another cloning company announced a new technique that could reduce the cost of dog cloning to about $50,000 within three years.
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