The process of evolution has to use what is naturally available. DNA, the replicating material that started life (well, they say it was RNA first, right?, but going on…), is going to be used in all future replications throughout the evolutionary tree of life. Thus, we find that DNA is the common denominator in all life-forms. It would seem that a God would not be constrained to one particular replicating molecule—DNA. A God could use any particular molecule and any particular combination. That is, every life-form on planet earth wouldn’t necessarily have to be carbon based if an all-powerful, all-creative agent designed life. Wouldn’t we expect an all-powerful, all-creative mind to utilize creativity in the genome of living creatures? Wouldn’t we expect evolution to be restricted to the materials and replicators that are available?
What we will next hear from the theistic perspective is “God designed the laws of chemistry in such a way that of course we would naturally live on an earth with certain physical parameters which would necessarily be followed by a specific chemical make-up of life-forms.” Okay, there you have it. The reason why things flow the way they do is because Zeus ordered them to.
Just because life appears to be designed doesn’t mean it was the product or result of some higher, governing intelligence. If we look closely, life appears to have an intrinsic design for survival and reproduction. This perceived “design” is entirely natural. This design is formulated by physical forces that are part of this world we observe.
When you observe the complexity and design of a kangaroo or a leopard or of a human you realize that the complexity and design of these organisms does not have its purpose in some supernatural concept but instead, in natural concepts such as survival and propagation of genes.
Just because a zebra or any other mammal is complex and appears to be designed doesn’t mean these creatures come from an intelligent being who has a supernatural plan for their temporary existence on earth. What we actually see is that physical properties that are part of these creatures are explained in natural, material ways. Why wouldn’t we extend this to humans as well?