This composite image of brain scans shows two traits of a highly impulsive individual. The cool colors in the midbrain are indicative of a decrease in dopamine receptor levels while the warm colors show elevated levels of dopamine in a different part of the brain called the striatum. Joshua W. Buckholtz and David H. Zald hide caption

itoggle caption Joshua W. Buckholtz and David H. Zald

A Pleurosigma, a type of phytoplankton in the ocean. Phytoplankton generate more than half of the Earth's oxygen. Harry Taylor/Nikon Small World hide caption

itoggle caption Harry Taylor/Nikon Small World

Scientists studied the Manduca sexta caterpillar under X-ray and found that when caterpillars walk, their guts move forward first, followed by the rest of their bodies in a rippling movement. Ted Kropiewnicki/Tree of Life Web Project hide caption

itoggle caption Ted Kropiewnicki/Tree of Life Web Project

Anthropologist Brian Richmond is trying to determine what the footprints of modern humans can tell us about how we evolved. NPR hide caption

itoggle caption NPR

Voice blindness, or phonagnosia, is a rare disorder that has to do with how the brain processes voices. hide caption

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The sediment levels in San Francisco Bay are going down, leaving wetlands with less protection from rising sea levels. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images