Over time, our beliefs begin to blend into our identity. Your belief in CrossFit makes you a CrossFitter, your belief in climate change makes you an environmentalist, and your belief in primal eating makes you paleo. When your beliefs and your identity are one and the same, changing your mind means changing your identity—which is why disagreements

So in the twenty-first century religions don’t bring rain, they don’t cure illnesses, they don’t build bombs—but they do get to determine who are “us” and who are “them,” whom we should cure and whom we should bomb.

Your Primitive Mind disagrees. For your genes, what’s important is holding beliefs that generate the best kinds of survival behavior—whether or not those beliefs are actually true.1 The Primitive Mind’s beliefs are usually installed early on in life, often based on the prevailing beliefs of your family, peer group, or broader community. The Primiti