A mischief of mice might not sound like the most fearsome crime fighting crew imaginable — but that might be about to change.
A fleet of the rodents trained in just five days by Chinese scientists is reportedly capable of sniffing out bombs, narcotics, and just about anything else you can think of — potentially offering a cut price alternative for sniffer dogs the world over.
A team at the Chinese Academy of Sciences' Kunming Institute of Zoology has taught a fleet of the rodents to recognize different smells with 98 percent accuracy, and says mice could put canines out of a job.
It was a simple and quick process. First, the researchers deprived 15 mice of enough water for a week. Then, they introduced them to a sensor that released drops of water when the mice touched it. Next, they locked the mice in groups of five inside a briefcase-sized box before releasing two different smells.
If the mice pressed the sensor when one of the smells was released, they got the water reward. If they pressed the sensor when the other smell was released or when there was no smell, the reward was decreased or eliminated. The responses were transmitted wirelessly, with a computer aggregating the responses from all five mice rather than just one, to increase accuracy. After five days, all the mice learned to press the sensor for the correct smell, even when released in low concentrations, with an almost perfect score.
Each box cost less than $16 to set up — which combined with the fact that mice themselves only cost a few dollars makes the rodents a lot less pricey than dogs.
"It is a fully automated process. Human intervention in training will become history," said Ma Yuanye, a neurologist who led the research, in a paper published in the journal Scientific Reports and reported by the Shanghai Morning Post.
Ma's research took place in China's Yunnan province, which borders several southeast Asian countries and is something of a hotbed of terrorism and drug trafficking. It's not the first time the scientist has looked at the potential for unconventional animals to carry out sniffer detection work — in 2005 his team started their work with bees.
"When we used the bee method we had a problem: many people were afraid of getting stung," Ma told VICE News. "And several of our students actually did get stung, so that's one of the reasons we stopped, in 2008. And anyway, a study that later came out showed that a bee's sense of smell is not as sensitive as a mouse's."
is the latest in a recent flurry of developments in the world of sniffer rodents. In 2012 researchers at Hunter College in New York bred genetically-modified mice with super-strong senses of smell that could detect landmine explosives. Also in 2012 Herzliya-based BioExplorers, an Israeli company, developed an airport security scanner that used mice to detect suspicious materials.
In 2013 Holland became the first country to use trained rats in civilian police investigations, with a team of five brown rats with the ability to detect drugs and explosives being unveiled. Rats have also been used in Tanzania and Mozambique to sniff out land mines.
Although Ma's mice were not genetically modified, he pointed out that another advantage of using them instead of dogs for scent detection was the fact their genes could be altered to improve their sense of smell, as the New York researchers did in 2012. "We have sound knowledge of the genes of mice and it's much harder to modify the genes of dogs — there are so many types of them," he said.
China's police force currently imports its sniffer dogs from Germany, while it costs around $5 to buy a mouse domestically. Their small size is also an advantage on disaster jobs, where they might have to pass through rubble with a camera attached to help rescuers find survivors.
However Ma is not ready to send all of China's sniffer dogs to early retirement just yet. "They do have some merits that mice don't have," he said. "For example, they can save people in emergency rescue situations — a mouse can't actually save anyone. So the dogs couldn't all be replaced, but perhaps most of them — and I think that would be the case abroad, too."
Additional reporting by Cissy Young.
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