I have been thinking about this for a while that, human bodies are severely outmoded for a while. We are not evolving fast enough to catch up with our technology and our body becomes more and more inefficient.
Take our physical strength as an example. At first we run, and if we stumble our bodies can naturally handle that. Then we ride horses, and if a horse stumbles on something then rider will probably get hurt but will still have a large chance of survive.