Humans are way too smart.
We know to much. We understand the way things are created and why living things do things they do and much much much more, and that's scary. We have theories of how our universe is created, and it's kind of ruining our lives. We're too familiar with the theories and facts and it takes away the mystery, therefore taking away alot of our imaginations and worrying about unecessary things, like the origin of our universe or where we go after we die. We can't live in the present, we can't apprechaite anything. We are always thinking about the future and the past.