U.S. Park Police officers arrest demonstrators in front of the While House on Thursday. They were protesting against a proposed 1,700-mile-long pipeline that would carry oil from the tar sands in Alberta, Canada, to the U.S. Gulf Coast. Maggie Starbard/NPR hide caption

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The brain "seems to be specialized in alerting us to things that are emotionally important to us — either positive or because they're scary," a scientist says. iStockphoto.com hide caption

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Harold McGee writes that the flavor of most vegetables exists to deter others from eating them — which may explain the pungency of mustard greens. iStockphoto.com hide caption

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Phosphates and bitters, a mixture of herbs steeped in alcohol, are part of the revival of old-timey soda fountain drinks at places like PS7's in Washington, D.C. Maggie Starbard/NPR hide caption

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In preparing the public for a disaster, officials want to make the right call, but they also want to avoid blame. Win McNamee/Getty Images hide caption

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"Can something be called chicken or pork if it was born in a flask and produced in a vat?" asks Michael Spector. "Questions like that have rarely been asked and have never been answered." iStockphoto.com hide caption

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