Retailers' Black Friday ads and other parts of the holiday season are designed to tap into a very ancient part of our brains. Paul J. Richards/AFP/Getty Images hide caption

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NPR producer Olly Dearden is a fan of most classic Thanksgiving dishes, but calls sweet potatoes topped with marshmallows a "culinary abomination." Stephen Little/Flickr hide caption

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Festivalgoers browse for books during the Miami Book Fair International. PBS will provide live coverage of the fair's events over the course of three days this year. Roberto Schmidt/AFP/Getty Images hide caption

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The scene at the registers in a Braintree, Mass., Target store on Black Friday. Allison Joyce/Getty Images hide caption

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Shoppers wait to get inside of a Best Buy store on Nov. 25 in Naples, Fla. Spencer Platt/Getty Images hide caption

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