A new study finds that orca mothers still feed their adult sons. It's a bond that may come with costs, researchers say. David K. Ellifrit/Center for Whale Research / NMFS research permit #21238 hide caption
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A glass is filled in with water on April 27, 2014 in Paris. Scientists studying what makes us thirsty have found the body checks in on our water consumption in several different ways. FRANCK FIFE/AFP via Getty Images hide caption
Thirsty? Here's how your brain answers that question
Polar bears are a great example of natural selection and evolution. But how did this ball get rolling? Remko de Waal/AFP/Getty Images hide caption
"Better Together" will illustrate a story about bird personalities and cooperation when the book Great Adaptations is published in the fall. James Munro/Courtesy of Breadpig, Inc. hide caption
A man reaches for a wooden cross in the sea during an Epiphany ceremony in the Greek port of Thessaloniki on January 6, 2011. Sakis Mitrolidis/AFP/Getty Images hide caption