Many of the most memorable, meaningful, and exhilarating experiences in my life are derived from times that were desperate, physically gruelling and dangerous. I think it's what we're designed for. A ship is safe in harbour but that's not what ships are for.

The periods of depression in my life were quite safe and comfortable, and strongly associated with wondering if my life really matters, and you can't think about that too hard because when you do, you recognize that, no, your life is actually pretty trivial in the grand scheme of things.

Hunter Gatherers didn't have that problem, because their whole world revolved around their one little tribe, and at that scale, yes, their actions and choices really did matter.