September 15 - Darwin in the Galápagos

On September 15, 1835, naturalist Charles Darwin arrived at the Galápagos Islands, nearly 1,000 miles west of Ecuador in the Pacific Ocean. He was a crew member of the second voyage of the HMS Beagle, on its mission to survey South America and circumnavigate the globe. In the next five weeks, Darwin and others made geological and biological observation on four of the 18 main islands of the volcanic Galápagos archipelago. Though Darwin focused on geology and had no expertise in ornithology, he collected what he called mockingbirds (later known as “Darwin’s finches”) and other birds on each of the islands, though he did not label them for location. Back in England, in 1837, an ornithologist found that the birds were differing species of finches, each unique to specific islands, each with beaks that had been adapted over time to specific habitats. This discovery, and the knowledge that tortoises differed from island to island, were critical in the development of Darwin's theory of natural selection explaining evolution, presented in The Origin of Species (1859).