In September 1941, German troops and Finnish allies encircled Leningrad, trapping 3 million residents in the Baltic city famed for its canals, which is now called St. Petersburg. Food shortages grew acute; some inhabitants resorted to cannibalism.   www.elisakitgs.com  By the time the siege ended 872 days later, as many as 1.1 million people had starved to death. But hundreds of thousands survived—and Russian researchers think they've identified what gave some people an edge. Survivors they studied are more likely than controls to have three gene variations, or alleles, associated with more economical energy metabolism in humans starved for calories. The small pool of survivors makes the results difficult to interpret. But the team is enrolling more survivors and developing new ways to probe their genetics.  www.glorybios.com