Scientists have been given the go-ahead to set up a mouse library to help disease research. The pan-Europe project aims to produce embryonic stem cells for 20,000 mutated mice to help scientists find out how genes cause conditions such as cancer. Scientists believe mice will play a “pivotal role” in understanding more, as 99% of human genes are found in the animals. One area of research on the mice will be why red heads can stand more pain. The link between red hair and a greater pain threshold was first established eight years ago. In 2004, a Canadian team identified the gene responsible for the effect - and now scientists across the world are using mice to try to establish why in the hope of developing pain killing drugs.