http://news.smh.com.au/scientists-create-fearless-mouse/20071214-1h3x.html

The age-old animosity between cats and mice could be a thing of the past with genetically modified mice created by Japanese scientists.

Scientists at Tokyo University say they have used genetic engineering to successfully switch off a mouse's instinct to cower at the smell or presence of cats - showing that fear is genetically hardwired and not learned through experience, as commonly believed.

The findings suggest that human aversion to dangerous smells like that of rotten food, for example, could also be genetically predetermined, he said.

Kobayakawa said his findings, published in the science magazine Nature last month, should help researchers shed further light on how the brain processes information about the outside world.