I'm not exactly well-read, but Peter Wessel Zapffe's view of the human condition, as set forth in The Last Messiah, resonated with me. He considers the over-evolved human intellect to be the source of existential anguish, due to its inherent need to find meaning in a fundamentally meaningless world, and identifies four "consciousness-limiting" coping mechanisms by which people stave off panic. In depressive states, the mind may be seen in the image of such an antler, in all its fantastic splendour pinning its bearer to the ground.The tragedy of a species becoming unfit for life by over-evolving one ability is not confined to humankind. Thus it is thought, for instance, that certain deer in paleontological times succumbed as they acquired overly-heavy horns. The mutations must be considered blind, they work, are thrown forth, without any contact of interest with their environment.