It should come as no surprise that elephants have been considered for landmine detection. Ashadee Kay Miller, a postgraduate student from the University of Witwatersrand, explained that these animals have an exceptionally high number of olfactory receptor (OR) genes at nearly 2,000 OR genes. The higher the number of OR genes, the better the sense of smell. With dogs having just 811 OR genes and rats having 1,207, this makes elephants among the best sniffers in the animal kingdom.
With this in mind, Miller and her colleagues put their smelling abilities to the test. They recruited three African elephants from Adventures With Elephants, an educational tourism facility located in Limpopo, South Africa. The researchers utilized a rewards-based training system to teach the elephants how to identify TNT by scent -- initially, among blank and odorless samples, then among distracting and strong-smelling odors.
According to DailyMail.co.uk, the researchers placed the samples in buckets that formed a straight line. The elephants were then tasked with walking beside and investigating the contents of each bucket, then raising and waving their front leg over the bucket they thought had TNT.
Of the 97 TNT samples used during the trials, the elephants only missed out on one. This put their sensitivity score at 99.7 percent, with sensitivity being defined as the “propensity to indicate whenever a target substance (in this case TNT) is present". By comparison, TNT-detection dogs have a sensitivity score of 93.7 percent.
However, the elephants racked up a lower selectivity score, or the “propensity to only indicate TNT, and not just any odorous substance". They made six false-positive identifications, having mistaken five out of 53 samples of acetone for TNT, as well as one out of 24 samples of petrol. Their selectivity score came to 95.1 percent, which is lower than the 100 percent scored by dogs.
“Our findings indicate that elephants are almost five percent more likely than dogs to indicate the presence of TNT when, in fact, there is none. But dogs are almost six percent more likely to miss TNT than elephants are,” noted Miller. She then added: “It's obviously better for TNT detectors to be prone to false positives rather than false negatives: in fact it could be the difference between life and death.”
As effective as elephants are at smelling out TNT, their massive size and weight makes them disadvantageous as infield TNT detectors. In lieu of actual fieldwork, elephants could instead be used to provide demining operations support from the sidelines.
“Samples collected via Remote Explosive Scent Tracing by unmanned vehicles such as drones could be sent to the elephants for screening. The information gathered from TNT-detection elephants could be passed on to demining teams working at the front lines, even before they are deployed,” said Miller. “This early warning system could potentially save the lives of the deminers and their dedicated biosensor companions.”
More than just demining efforts, Miller has suggested that elephants' keen sniffing senses could be useful in other areas such as disease detection. Currently, specially trained dogs are being trained to screen patients for acute and chronic diseases. The accuracy and reliability of these animals has proven greater than that of machines in some cases. (Related: Scientists STUNNED: Dogs are able to detect cancer more accurately than many laboratories)
Elephants have several advantages over dogs, Miller explained: “They require less maintenance training than dogs to keep them on the target scent. In addition, given their longevity — they can live to around 60 years in the wild — elephants, once trained, could serve as long-standing biosensors that far outlive any of their current biosensor counterparts.
“And, importantly, biologically appropriate tasks that engage natural behaviors to gain reward is highly stimulating for captive animals. So not only could elephants potentially save lives while sniffing out danger – they could have fun at the same time.”
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