It's human nature to form groups — families, friends, online communities. We love to be surrounded by people similar to us. But that can also make us discriminatory and defensive. And social media makes that instinct worse. Today, we look at how our brains evolved to connect and divide, and what that means for the problems we face in our modern world. This episode was first broadcast in April 2023. Looking for something to listen to next?  Check out another All in the Mind episode, The Certainty Myth.