Here’s what you’ll learn when you read this story:Urbanization has had visible morphological effects on chipmunks and voles in the Chicago metro area. And it isn’t just New York City—Chicago rodents have become so used to city life that they have actually evolved for urbanization. And as a result of all the horns honking, brakes screeching, and everything else that turns up the volume of a bustling city, voles have developed smaller inner ears to turn down the noise. Related Story Inside the Chernobyl Dogs’ Strange Genetic ChangesLike chipmunks, urban voles had flatter skulls and auditory bullae that were further back. It became obvious that chipmunks in urban areas are increasing in size, and their rows of teeth have grown shorter.