Rodent ancestors combined portions of blood and venom genes to make pheromones

Experts who study animal pheromones have traced the evolutionary origins of genes that allow mice, rats and other rodents to communicate through smell. The discovery is a clear example of how new genes can evolve through the random chance of molecular tinkering and may make identifying new pheromones easier in future studies. The results represent a genealogy for the exocrine-gland secreting peptide (ESP) gene family.