Cavemen needed some sort of shelter from the weather and elements in order to survive. Even though their sod and plant covered roofs were well insulated and kept them warm, it did not keep out the rain or vermin. If a caveman did not find an empty and waterproof cave, he had limited resources to build his own roof. Every civilization used whatever materials and tools were available to create their roofs. We can learn a lot about the creativity and advanced technology of a civilization by their roofs.