WHILE track and field athletes compete at the Olympic games this week, genetically engineered mice are also breaking records. The rodents, dubbed “marathon mice”, can run almost twice as far as normal mice. Drugs that might have a similar effect are already being tested on people, raising fears that athletes could soon have yet another way to cheat.
“This is the first animal engineered for increased endurance,” says Ronald Evans of the Salk Institute in La Jolla, California. His team wanted to find out if a protein called PPAR-delta, which is known to help burn fat, also helps fight obesity. In the body, the greatest consumer…
