for National Geographic News
Some people say that old dogs can't be taught new tricks. But don't tell that to Larry Myers.
A professor of veterinary medicine at Alabama's Auburn University, Myers has trained unwanted dogs to detect everything from drugs and bombs to off-flavor catfish and agricultural pests.
Myers says that, with proper training, just about any dog can learn to detect a unique scenteven the odor of certain cancers
"Some dogs are more conditioned to training than others. But that's differences between individuals [not breeds]," he said. Myers usually works with dogs rescued from the pound.
James Walker, director of the Sensory Research Institute at Florida State University in Tallahassee, says canines' sense of smell is generally 10,000 to 100,000 times superior to that of humans.
Walker plans to train dogs to detect prostate cancer in human urine later this year.
It's uncertain why dogs are so much better at smelling than humans are. But Walker says it is probably related to how dogs are "wired."
Recent research shows that dogs have a greater variety of smelling receptors in their noses. They also have a greater convergence of neurons from the nose to the brain than humans do.
"It is clear that the dog has a much greater proportion of its brain devoted to smell than is the case with humans," Walker added.
Myers, the veterinary professor, notes that, in general terms, dogs and humans are similarly wired for smelling. But he adds that more research is needed to determine the subtle differences between man and mutt, including the mucus that overlies our different smelling receptors and the molecules that make up those receptors.
Cancer represents the frontier of dog-detection research. Anecdotal evidence suggests it may be possible for dogs to sniff out certain malignancies. But the science still lags, according to Myers. "We hope we can. We think we can. But we don't know that we can."
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