Anxiety is a uniquely human disease. It’s an unwelcome byproduct of our ability to imagine: to create a world in our minds that does not match the immediate input of our senses. Because we can feed these fabricated images and experiences back to ourselves, and because the less sophisticated parts of our brains lack the ability to distinguish between those imagined experiences and real ones, we can trigger the same biological fight-or-flight responses in our bodies that are meant to deal with real, immediate danger simply by thinking about hypothetical threats.

The book Stumbling on Happiness clued me in to some of these weird psychological wirings that we have. Another fascinating one that I’ve mentioned before is that we have enormous trouble disentangling feelings we are actually experiencing at the present moment from feelings we imagine ourselves to be having in hypothetical situations. An everyday example: when you’re inside a warm building, the idea of going outside into subzero cold doesn’t seem nearly as daunting as it does when you’ve been walking down the street into the wind for ten minutes. It’s nearly impossible to separate the current feeling of comfort and warmth from the imagined experience of walking in the cold.

There is a reason that anxiety does not exist in the rest of the natural world. Although nature is hardly the gold standard for human behaviour, it’s often a useful example; it’s had ridiculously long to work out the kinks and settle into successful ways of doing things.

Evolution, for example, is often a hugely useful approach to developing anything from poems to dishwashers to computer software. Evolution has no anxiety whatsoever. It constantly tests new variation, using the real world to eliminate the unsuccessful attempts. To evolve is to find the better way by messing up as much as you can, fearlessly.