Populations of frogs and other amphibians are declining at an average rate of 3.7 percent each year, according to a new U.S. Geological Survey study. Karen Bleier/AFP/Getty Images hide caption

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For centuries, Russians believed putting a brown frog in their milk would keep it fresh. Now scientists are finding chemicals in the frog's slimy goo that inhibit the growth of bacteria and fungi. Stefan Arendt/Corbis hide caption

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