OF A FEATHER Researchers have found that mutations in pigeon DNA can control a variety of traits, including the directions of their feathers grow, like in this Jacobin pigeon. Charles Darwin raised pigeons and was interested in their breeding as an extreme example of domestic selection. ”And stop calling them ‘skyrats,’” said Darwin, “before I go all Galapagos Tortoise on your ass.” (Photo: Robert Clark / Institute via The New York Times)