Whenever I read about Darwin and his journeys and discoveries the first sentence always includes the reference to the HMS Beagle. While this is very interesting when studying the story of Darwin himself, but even in Biology textbooks the HMS Beagle is mentioned. What is the importance of which ship Darwin sailed to Biologists or to the overall story of Darwin? I understand that it is a historical detail so it should/could be noted, but it is noted in EVERY article on Darwin or evolution in EVERY discipline. Made me wonder whether something interesting was going on with it.
Historians put emphasis on it as the "pivotal moment" that provided many of the experiences and impressions that eventually (later!) led to Darwin's theory of evolution. It was on the Beagle that Darwin read some of the foundational texts that influenced his theory (e.g. Malthus), and it was on the Beagle that he encountered the weirdness of nature first-hand (the Galapagos, the finches) and also some of the key issues that impacted his views of human beings (the Fuegians, slavery in Brazil). Darwin himself would have identified as one of the major, foundational experiences in his life.
As for biologists, though, that's a separate question. Why do biologists, and biology textbooks, even talk about Darwin? And do they represent the Beagle voyage accurately (from the point of view of historians)? Historians of science often talk about the kinds of histories you get in textbooks as a specific genre of "textbook history of science" — it serves a pedagogical and institutional role that is quite separate from the concerns of historians. Among the roles that "textbook history" serve are to give patterns of achievement for budding scientists, to exhibit exemplary scientific behavior, to situate heroes and villains for students, and to give a pattern for how science itself "works." In the Darwin case, my guess (I haven't read anything specifically on how they treat Darwin — I am not sure a study on this exists but it is the sort of topic that probably has been looked at by historians of biology) is that their story of the Beagle is about the scientist going into the field, finding evidence, coming back and processing it, and using the evidence to find a counter-intuitive and quite shocking theory that revolutionizes the world. (This is not how a historian would precisely see this, as an aside — it is more nuanced than this.) It also is a very heroic mode of science, the idea of this epic journey that leads (eventually) to intellectual fulfillment. As a contrast, many of the deep historical accounts of Darwin emphasize that he spent a lot of his time vomiting at home, very far from the field, in the actual periods in which he worked on his evolutionary theory — this is a far less heroic vision!
On Darwin himself, the biographies of both his Beagle work and his post-Beagle work that I like the best are those by Janet Brown (Charles Darwin: Voyaging and Charles Darwin: The Power of Place), but Adrian Desmond and James Moore's Darwin's Sacred Cause goes into very interesting territory with regards to how Darwin regarded the humans he saw on the Beagle (the Fuegians and the slaves) and how that shaped his later theories and politics.
On textbook history in general, the classic work is Thomas Kuhn's The Structure of Scientific Revolutions, which devotes a lot of space (and a lot of analysis) to the pedagogical function of textbook science history.
Hard to talk about Doc and Marty without the Delorean isn't it?