A mouse embryo grows from stem cells made by stressing blood cells with acid. The blood cells are tagged with a protein that creates green light. Courtesy of Haruko Obokata hide caption

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The sexually transmitted cancer is common in street dogs around the world. Noel Celis/AFP/Getty Images hide caption

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The superglue developed by scientists sticks to wet, bloody surfaces. Researchers hope the adhesive could one day seal a torn vessels or fix heart defects. Randal McKenzie / McKenzie Illustrations. hide caption

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There's data to support the notion that pot, or a drug based on its active ingredient, could help ease the fears of PTSD. Ted S. Warren/AP hide caption

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Research excavations like these in Siberia's Denisova Cave are yielding clues to the mating choices of early hominids. Bence Viola/Nature hide caption

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Yes, you could do this at home. Growing bacteria you find in a pile of dirt or a local pond might reveal the next big antibiotic. Charlotte Raymond/Science Source hide caption

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President Obama walks into an auditorium in the Eisenhower Executive Office Building Monday for a speech about World AIDS Day. Carolyn Kaster/AP hide caption

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Lefties don't necessarily do everything with their left hand, and the ones who do might not use the right side of their brain for language. iStockphoto hide caption

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University of California, Davis food safety field scientists Michele Jay-Russell, Paula Kahn-Rivadeneira, Anna Zwieniecka, Navreen Pandher and Peiman Aminabadi celebrate the first day of their experiment testing E. coli survival in soil. Courtesy of Fhon Saharuetai hide caption

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Researchers stroked babies' faces with a paintbrush while they watched the same thing happening to a baby in a video. How long the babies in the experiment watched the screen gave clues to what they were thinking. Courtesy of Maria Laura Filippetti hide caption

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The plate on the left contains about equal numbers of colonies of two different bacteria. After the bacteria compete and evolve, the lighter ones have taken the lead in the plate on the right. Courtesy of Michael Wiser hide caption

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An anatomical drawing shows the ligaments on the outside surface of the knee. The anterolateral ligament connects the thigh bone to the shinbone. Courtesy of University Hospitals Leuven hide caption

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