Genes Make Mouse That Roared

Japanese scientists have modified mouse genes to make rodents unafraid of cats in a dramatic experiment that offers insight into the origins of terror. The breakthrough shows that fear is largely genetically hardwired rather than learned through painful experience, researchers say. Some of the mice, whose nasal cells were altered by genetic engineering, even played with cats.

The study, published in Nature, raises the possibility of other intriguing investigations concerning fear. "People have thought mice are fearful of cats because cats prey on them, but that's not the case," said one scientist. "If we follow the pathway of related signals in the brain, I think we could discover what kind of networks in the brain are important for controlling fear."   (More genetics stories.)