A Nose for Trouble.(trained rats)

Shortly after the crack of a November dawn, in a sandy field near the Maputo-Harare railroad in Mozambique, Jullie, Josse and Johan went to work. These African pouched rats pressed their snouts to the ground in a 100-square-meter boxed-off area, known to contain land mines and unexploded ordnance, sniffing half-meter-wide lanes for telltale explosives vapors. Bart Weetjens, founder of a Belgian-based group known by the acronym APOPO that researches the use of animals in hunting land mines, was growing frustrated. For the past two days, his rat pack had failed to find a single mine.

That morning the rats finally got the hang of it. By 9 o'clock, when 30-degree Celsius heat forced a halt to the work, the rodents had managed to find nine mines. In the next eight days, the rats found a total of 22 mines--a success rate of 100 percent, as established by subsequent sweeps of the area with metal detectors. "We opened a bottle of champagne in the camp to celebrate," says Weetjens. The rats got a few scrumptious bits of avocado.

Weetjens's experiment is the first time rats have been used to find land mines. If APOPO can overcome some obstacles--including the animals' sensitivity to temperature and climate--rats may soon take their place alongside metal detectors and dogs as standard tools in the dangerous, expensive and time-intensive work of humanitarian demining. That would be welcome news. At present more than 100 million land mines are deployed in 90 countries, and they kill or maim 40 to 55 people per day on average, according to Red Cross and RAND Corporation estimates. Combatants lay 40,000 new mines each year. At the present rate, it will take 500 years to remove them all, according to a recent RAND study. The need to quicken the pace of demining is urgent, and experts have come to believe that animals hold the most promise.

The traditional manual demining technique of sweeping the ground with a metal detector is tedious and inefficient, turning up hundreds of false positives--bullets or other scraps of metal--for every actual mine. Mine-sniffing dogs, introduced a decade ago, have produced a fivefold increase in speed, largely because ...