People love lists — mostly, I think, so that they can argue about what’s on them and what’s not. That means much of the labor of producing this year-end issue involved arguing about what to leave out. What remains are the stories that reveal major shifts in human knowledge, reflect science’s biggest challenges and highlight the compelling and intriguing ways that science can illuminate the world around us. Or, so we would argue.
What stood out this year was the unprecedented Ebola epidemic that hit West Africa and extended its tendrils around the globe. Other standouts included the highs and lows of the search for gravitational waves, a saga that had people on the street wondering about cosmic inflation and the history of the universe. And, of course, the spectacle of landing a robotic spacecraft on a comet, an awe-inspiring moment even for those who don’t consider themselves science fans. Other advances in our top five received less public attention, but are a marvel all the same. One is researchers’ increasingly sophisticated ability to extract and analyze ancient DNA, which is now being used to rewrite early human history. And neuroscientists built new roads into the terra incognita of human memory this year, offering a futuristic way to take the emotional sting out of bad memories.