How Vampires Evolved to Live on Blood Alone

Any mad scientists planning to genetically engineer Dracula this Halloween should look to the vampire bat for inspiration. New research pinpoints some of the genetic changes that allowed them to evolve to subsist on a diet of pure blood. Key among those is a knack for keeping their meals from coagulating. They do so with the help of a gene found in other animals — plasminogen activator. In humans the gene protects against heart attack by producing proteins that bust up blood clots and clear vessels. Previous research had shown that vampire bats activate the gene in their saliva, too