The author does go into the people who wanted to have all the credit, or at least share the credit for his discovery after the book was published and appeared to be the book of the century--which was an accomplishment indeed. A decade later, evolution would be embraced by the scientific community in total, and Darwin remains a household name over a century later. The earliest biologist and observer of the natural world was Aristotle, who closely studied sea life, and his book "The History of Animals" was closely studies by an early mentor of Darwin's.
Te bulk of the book is going over the various pieces of information that helped inform Darwin's final work, including people that he worked directly with. One chapter is devoted to the work of his grandfather, who would undoubtedly have been very proud of the work that his grandson accomplished, but also goes to show that one's personal experiences and history can give one a great advantage. The other advantage that Darwin had was financial support. His father may not have thought much of what he was doing, but he didn't cut him off financially, and that was different from the situation that a number of scientists who went before him encountered. They had great curiousity and ideas, but had to quit pursuing them in order to make a living.
Another ingredient of success for Darwin was luck--he had a fair amount of it, but most influential was his meeting Robert Edmond Grant one fine day on the beach. Grant was the eminent comparative anatomist of his time, and Darwin met him as a teenager, and worked with him. The book has a lot of details about the wealth of what was known prior to Darwin's epic book, and why it was that others might have chosen not to take on the church and religion in putting forth such a theory--that Darwin was not just a great observer but also that he was in the right place at the right time.
