December brought storm clouds to the Porter Ranch neighborhood in Southern California's San Fernando Valley. David McNew/AFP/Getty Images hide caption

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Criminologist Joseph Richardson is skeptical that the federal government alone can solve the data problem for police shootings. "There has to be a more pioneering, innovative approach to doing it," he says. Spotmatik/iStockphoto hide caption

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Sylvester Williams, a Denver Broncos nose guard, nabs Isaiah Crowell of the Cleveland Browns last October. If measured by BMI, Williams is obese. AAron Ontiveroz/Denver Post via Getty Images hide caption

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When so-called senescent cells were removed from mice, they were healthier and lived longer than mice that still had the cells. Philippe Merle/AFP/Getty Images hide caption

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Scientists have the ability to use DNA from three adults to make one embryo. But should they? A. Dudzinski/Science Source hide caption

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A Chipotle Mexican Grill employee prepares a burrito for a customer in Seattle. The CDC believes the two recent E. coli outbreaks at Chipotle restaurants are over. Stephen Brashear/AP hide caption

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When a baby is born by cesarean section, she misses out on Mom's microbes in the birth canal. Sarah Small/Getty Images hide caption

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Ben Lecomte has swum across the Atlantic Ocean, and now he aims to traverse the Pacific, which will take him five or six months. Bongani Mlambo/The Longest Swim hide caption

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BJ Miller speaking at TED. Bret Hartman/TED hide caption

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