I think you are making evolution sound less scientific than it is. One thing that is a certifiable fact is that species are not fixed. As shown by the fossil r

I think you are making evolution sound less scientific than it is. One thing that is a certifiable fact is that species are not fixed. As shown by the fossil record, new species can show up and old species go extinct. And in a smaller time scale, the artificial selection that happens with domesticated plants and animals shows that there can be significant changes in species. Once we realize that some sort of evolution must be happening the question becomes to explain what mechanism is behind it. One of the initial hypothesis was the Lamarckian theory that animals can pass on to their offspring traits that they acquired via their lifestyle. This was eventually proven false when we found no evidence that this is not how genetics actually works. Darwin's theory of natural selection is still with us because it withstood the test of time, not because it is unfalsifiable. This is very clear if you read Darwin's books. He was aware that there are many things that would contradict his theory if they were true and he spends lots of chapters refuting them. A more modern source I like to point to is Talkorigin's list of 29 evidences for macroevolution. It covers many of the things known to Darwin and more recent developments such as genetics, molecular biology and new fossil finds. http://www.talkorigins.org/faqs/comdesc/ http://www.talkorigins.org/faqs/comdesc/