What's the evolutionary reason for chronic depression and anxiety? As a sufferer it's something I've often wondered. Is there a reason or is it simply a design fault with our brains because they're too big? It seems counter-intuitive that there'd be an evolutionary benefit for something you'd expect to make somebody an under-achiever. But hang on: we did most of our evolving in palaeolithic times, so that's the period we need to consider. I imagine myself in those times. I'm pretty sure I'd be a follower rather than a leader, but maybe a follower with a reasonable amount of respect because he's quite good at making arrows and he once came up with a new design of spear that's easier to throw. I'd be reasonably good at gathering, and probably not too bad at hunting as long as the weather was OK and I could be arsed. But if there was a territorial dispute, or if our tribe had decided to try to expand into neighbouring territory, I have a good idea that the other lads would say, "Oh, it's OK, Neil... we know you're crap at this kind of thing... why don't you stay behind and entertain the kids." So three days later and they're still not back, some of the randier women are getting chilly at night and I'm better than nothing. Five days later the lads get back but half of them have been killed and a few of the survivors are maimed. So there are now quite a few women without men and somebody has to step in.