Happiness is not our default state of mind. Our brains are hard-wired to ensure our survival, and so they are on constant alert for threats. Even though we live in the most advanced technological society in the history of mankind, at the deepest level, our primal survival instinct is still intact from our caveman ancestors. We are not conscious of it, but our brains are constantly scanning for things that might eat us, harm us or take things from us. Our modern emotions translate this into negativity, producing cortisol, a hormone that can cause damage over the long term.