Have you noticed how complete nature is?
When something in nature ceases to live, it's consumed by the nature within and without it.
Consider the leaf that falls from a tree. After serving its purpose of feeding the tree by absorbing sunlight to produce food, exhaling oxygen in return for carbon, it falls to the ground and is returned to the soil. The leaf is consumed by the little creatures on and in the soil, breaking down the leaf's matter and reintroducing the leaf's matter back into the soil. The soil, straining this matter through water, replenishes the tree's root system. A purely recyclable and efficient system.
Consider the mammal who after perishing, if it isn't consumed by another life form, is consumed from the outside and from the inside. If no flies had opportunity to lay eggs resulting in maggots, the body itself produces enzymes which will begin the natural process of decomposition. In due time, the matter would have returned to the basic components it was comprised of. A purely recyclable and efficient system.
Consider now what human hands produce and their byproducts. Can you name one product of man which efficiently returns to its original state without any type of contamination, useless byproduct or negative impact on nature?
If the natural world around us all came about by chance, as the argument of order out of chaos which produced an ordered world and by default an ordered civilization of human beings, how amazing the perfect and complete cycle.
Why has man begun to deviate from nature's perfect order? Why hasn't man continued a life following nature's perfect example of regeneration?
Archaeologists find that human beings of long ago lived in harmony with the natural order around them, building homes and fashioning tools from items needing little modifications.