Fear may be linked to the sense of smell and can be switched off simply by shutting down certain receptors in the brain, Japanese scientists have found. In an experiment with mice, the researchers identified and removed certain receptors on the olfactory bulb of their brains — and the result was a batch of fearless rodents. To prove their point, the scientists showed pictures of a brown mouse within an inch of a cat, sniffing up its ear, kissing it and playing with its predator’s collar.
“They detect the smell of predators … like a cat and urine of a fox or snow leopard, but they don’t display any fear. They even show very strong curiosity but they can’t tell the smell is a sign of danger,” said Hitoshi Sakano at the University of Tokyo’s department of biophysics and biochemistry. “So these mice are very happy with cats. They play with cats. But before taking the picture, we had to feed the cat,” he said.