Suppose you are Father God, or Mother Nature, or Mother God, or Father Nature — doesn’t matter — and you want to raise up a crop of mammals who can reason well about what’s true. At first you think, “No problem! I’ll just ex nihilo some up in a jiffy!” but then you remember that you have resolved to build everything through the painstaking process of evolution by natural selection, which requires small random shifts over time, with every step toward your target resulting in some sort of reproductive advantage for the mammal in question. Okay; this is going to be hard.

Given what you know about reasoning and truth, the mammal is going to have to have access to some way of abstractly representing the world to itself, or language. That in turn will require a community of language users; and that will require a community of beings who fare better through cooperation. This immediately raises the problem of how to evolve beings who are both selfish and social. Selfishness requires cheating whenever you can get away with it, but sociability requires trustworthiness. Striking a workable balance between selfishness and sociability is tricky, but not impossible, as anyone who has worked in corporate knows.

Read more here