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

itoggle caption Ted S. Warren/AP

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

itoggle caption Bence Viola/Nature

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

itoggle caption Charlotte Raymond/Science Source

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

itoggle caption Carolyn Kaster/AP

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

itoggle caption iStockphoto

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

itoggle caption Courtesy of Fhon Saharuetai

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

itoggle caption Courtesy of Maria Laura Filippetti

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

itoggle caption Courtesy of Michael Wiser

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

itoggle caption Courtesy of University Hospitals Leuven

Bob Adams is a lab animal veterinarian at Johns Hopkins University. Maggie Starbard/NPR hide caption

itoggle caption Maggie Starbard/NPR