Cypress:
It doesn't matter how many years of work Darwin put into his book Origin of Species. It's still a work of science fiction in light of the fact his assumptions were proven to be false. For instance, his claim about natural selection has proven to be patently false. Paleontologists (people who study fossils), including those that are pro-evolution, have been forced to acknowledge that the idea of natural selection aka the survival of the fittest does not hold water. Notice below what a couple of them wrote in their peer reviewed papers.
"The fossil record flatly fails to substantiate this expectation of finely graded change." (Eldredge, N. and Tattersall, I., The Myths of Human Evolution, 1982, p. 163.)
"Instead of finding the gradual unfolding of life, what geologists of Darwin's time, and geologists of the present day actually find is a highly uneven or jerky record; that is, species appear in the sequence very suddenly, show little or no change during their existence in the record, then abruptly go out of the record. and it is not always clear, in fact it's rarely clear, that the descendants were actually better adapted than their predecessors. In other words, biological improvement is hard to find." (Raup, David M., "Conflicts Between Darwin and Paleontology," Bulletin, Field Museum of Natural History, vol. 50, 1979, p. 23.)