Chapter 4 AND IN THIS CORNER… LIVE! We saw earlier that life as we know it on our planet, began with and in the water. Water has a key role in our kind of existence. Consider that we humans are composed of seventy percent of that element we could almost say that we are sea animals adapted to the surface. Well, we must place ourselves there and think that, the planet is cooling, the water remains liquid longer, and it is accumulating in the lowest places by simple gravity simultaneously.