Scientists have lately made remarkable discoveries about our physical and mental well-being—and things that threaten it. In the article leading this section, a pair of Nobel Prize winners explain an amazing brain system that functions like a GPS, tracking us from point to point on a mental grid. Another article follows disease detectives in early 2016 as they figured out that the recent explosion in Zika virus infections was not caused by genetic changes, as some feared; rather human activity is very likely at fault. Recently researchers have had groundbreaking wins against another scourge, successfully treating some cancer patients with therapies that boost immune responses against tumors. Efforts to slow aging look like they might be starting to bear fruit as well. Learn, too, about an astonishingly easy gene-editing technology that can change DNA within sperm and eggs, potentially transforming humanity as the changes get passed forward through generations. The technology raises unnerving questions about what we will do with such power.