In 1831, the young Charles Darwin, then aged just 22, embarked on HMS Beagle. She was on a voyage of exploration, destined for unknown lands, and Darwin was the ship’s naturalist. During the five-year voyage, he observed, drew, and annotated the fauna and flora he encountered. In 1835, Charles Darwin set foot on the Galapagos Islands for the first time, and noticed that the same species showed differences from one island to the next. Sometimes these differences were very subtle, and in other cases they were much greater.