Of course this is mostly about the biology Darwin observed on his trip; it is absolutely amazing how much he observed -- geology nearly at its birth, fluid mechanics and its use by organisms to eat and disperse, the variation of species... but also all the people he met. It is profoundly obvious that he was of the egalitarian, liberal Wedgewood temperament. He admires the dashing horsemen of South America, but only when their gallantry extends to middle-aged native women; he is furious at the exclusion of a talanted black officer in a nowhere in the grasslands.
Also, when learning to use the bolas, he brings down the horse he's riding at the time.
Project Gutenberg file#944, The Voyage of the Beagle
So wrote clew in History (19th c.). , Science.