Oh wow. Origin of Species and The Double Helix are totally different. Origin is Science - or maybe even SCIENCE - this overwhelming tome that seeks to crush the dominant 19th C creationist paradigm under the weight of evidence favoring evolution by natural selection. It seeks to eliminate the bias of the scientist-observer (Darwin) and present the pure data. Sort of a 19th C Nature article, only with random French and Latin quotations. Double Helix is about all the personal quirks of the individual that Origin seeks to erase. Origin tries to close on an image of the majesty and beauty of the theory; Double Helix ends with James Watson thinking, "I'm in France, I'm twenty-five years old, and the girls aren't interested in me." Major difference in tone. A better comparison might be Origin of Species (http://www.talkorigins.org/faqs/origin.html) and the original letter to Nature about the structure of DNA (http://www.nature.com/genomics/human/watson-crick/index.html).