Mice have developed a single gene that allows them to avoid predators through their sense of smell.
The gene, TAAR4, helps mice to respond to a chemical that is enriched in the urine of carnivores, such as cats. While normal mice actively avoid the scents of natural predators, those missing the TAAR4 gene did not.
Current consensus is that removing a single olfactory receptor gene would not have a significant effect on how we perceive smell, but these new findings have cast that into doubt. Researchers are hoping to take these studies further to discover how this affects brain behaviour and how it may relate to human perception of odour.
Read more at Northwestern University