See an article about evolution, probably mean mankind lives in the house there is a reason that the ancestors lived in caves hundreds of millions of years of evolution demand, that is why people of caves have natural view and conquer the desire, that is the original gene at work, also is not difficult to infer, human demand for houses is so urgent.Animals and birds is basic in the outdoor environment to survive and live, bird songs, flexibility of fishes, the speed of the leopard...May not have a roof, humans will evolve more JueXue ability, high speed development today, we seem to have been degradation potential of more serious