New research suggests that the Delmar Divide, a socioeconomic and racial dividing line in St. Louis, not only separates people, it segregates wildlife. Washington University postdoctoral fellow Elizabeth Carlen’s study of one of St. Louis’ most common residents, eastern gray squirrels, demonstrates the phenomenon. She shares what she’s discovered about the ways politics have shaped the genealogy — and even evolution — of St. Louis squirrels.