The human body is chock full of limits. So much so that you are using electrons modulated at different voltages to communicate to another person instead of using analog mouth vibrations right now. The story of humanity is one of using tools to surpass those limits. Now as our technology advances we can understand the nature of human limitations, and possible novel ways of overcoming them, such as gene therapy or direct brain to computer interfaces. There is also the possibility that we will create our replacement capable of surviving the harsh realities outside of our comfortable planet.