Scientists in Russia say rats could one day be used like sniffer dogs, and detect explosives and trapped humans with their advanced sense of smell. Researchers in Rostov-on-Don at the Laboratory of Olfactory Perception (LOP) have been attaching electrodes to the rodents to monitor their brainwaves.

They then study how an unfamiliar or unusual substance affect the rat's waveforms. Dmitry Medvedev, the Head of the LOP, said, "Unlike a dog, a rat can get through the smallest crack where it seems it couldn't go. This way it could find its way deep under rubble and by its brain activity one could understand if there are, for example, people who are still alive, if it's worth clearing debris here or at another place, to rescue people more quickly".

They have already found that rats can differentiate between types of tea leaves through smell. However, they admit there is a long way to go until these rodents can be used outside of the lab.

"We can't say what substance it was by just analysing an encephalogram by sight. We are now trying to work out what substance it was with the help of mathematical analysis," Dr Medvedev added.

So-called 'sniffer rats' are already used in Tanzania and Mozambique to detect land mines and tuberculosis.