It is considered a theory because it is substantiated by evidence. In the scientific sense, a theory is a proposition that is supported by evidence, either direct or indirect. With out some of...
Darwin was by no means the first person to come up with a theory of evolution. However, he was the first person provide a mechanism by which evolution could occur. He called this natural selection...
They both attempted to explain the same phenomena by natural means. Both theories also used inheritence of parental characteristics to explain how species might evolve.
Previous theories were not particularly scientific. These were that God created all the species simultaneously 6000 years ago. No evidence exists to support that idea. Another theory was that animals...