Randy Nesse on why evolution left us so vulnerable to depression and anxiety

Yeah, I find this a shocking thing, Rob, and a disturbing idea. I mean, I always thought that natural selection would shape us for health and happiness and cooperation and long, happy lives. And anything different from that meant there’s something wrong with the system. But once you start studying how evolution shapes behaviour-regulation mechanisms, you realise that it doesn’t give a damn about us, that doesn’t give a damn about anything: it’s a mindless process that any genes that make individuals do things that benefit transmitting more genes — which basically means having more children and taking good care of them and getting resources to do that — any genes that make that happen will become more frequent. Any tendencies genetically to do things that make your life end sooner, or have fewer offspring, or have fewer resources, those are going to go away — and the whole system doesn’t care at all.