Study finds pigeons and other animals, like humans, can place everyday things in categoriesBy: Amy Mattson | 2014.04.02 | 12:00 AMPinecone or pine nut? Friend or foe? Distinguishing between the two requires that we pay special attention to the telltale characteristics of each. And as it turns out, us humans aren’t the only ones up to the task.According to researchers at the University of Iowa...