BREAKTHROUGH OF THE YEAR:Evolution in ActionElizabeth Culotta and Elizabeth Pennisi Equipped with genome data and field observations of organisms from microbes to mammals, biologists made huge strides toward understanding the mechanisms by which living creatures evolve The big breakthrough, of course, was the one Charles Darwin made a century and a half ago. By recognizing how natural selection shapes the diversity of life, he transformed how biologists view the world. But like all pivotal discoveries, Darwin's was a beginning. In the years since the 1859 publication of The Origin of Species, thousands of researchers have sketched life's transitions and explored...