" This hardened response to those on the “other team” is not an invention of modern American politics. It seems to be hardwired into the circuitry of our brains. The Old Testament is filled with stories of sometimes deadly tribalism, and scientific data gives us insight into why that happens. In 1968, elementary school teacher Jane Elliott conducted a famous experiment with her students in the days after the assassination of Dr. Martin Luther King Jr. She divided the class by eye color. The brown-eyed children were told they were better. They were the “in-group.” The blue-eyed children were told they were less than the brown-eyed children—hence becoming the “out-group.” Suddenly, former classmates who had once played happily side by side were taunting and torturing one another on the playground. Lest we assign greater morality to the “out-group,” the blue-eyed children were just as quick to attack the brown-eyed children once the roles were reversed.6 "

― Sarah Stewart Holland , I Think You're Wrong (But I'm Listening): A Guide to Grace-Filled Political Conversations