Do I Know You? An animatronic baby Tyrannosaurus Rex gives students a close look during a preview of the Australian show Walking With Dinosaurs in Melbourne last week. Mark Dadswell/Getty Images hide caption

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Nighthawks are known for their repeated "peent" call as they hunt for flying insects. Bill Bouton/Flickr hide caption

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Stone artifacts dating back 15,500 years suggest humans may have arrived 2,000 years earlier than previously thought. Courtesy of Michael R. Waters hide caption

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According to Dr. Lidy Pelsser's study, 64 percent of children diagnosed with ADHD are actually experiencing a hypersensitivity to food. hide caption

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The FBI used a new DNA fingerprinting technology to analyze the anthrax used in the 2001 mailings. These anthrax spores can live for many years. Janice Haney Carr/CDC Public Health Image Library hide caption

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