Scientist of the Day - Charles Darwin

Cactus finch from the Galápagos Islands, lithograph after drawing by Elizabeth Gould, The Zoology of the Voyage of H.M.S. Beagle, ed. by Charles Darwin, vol. 3, plate 42, 1839 (Linda Hall Library)

On Sep. 15, 1835, Charles Darwin, aboard HMS Beagle, sailed into the Galápagos Islands, 500 miles west of Ecuador. The Beagle had been at sea for almost 4 years, and Darwin was more than ready to get home to England. What he thought about having to spend 34 days surveying these volcanic islands, straddling the equator, before heading homeward across the Pacific, Darwin did not say.

HMS Beagle, watercolor by Owen Stanley, 1841, National Maritime Museum, Greenwich (rmg.co.uk)

There are 10 Galápagos Islands, most within sight of one another, but separated by straits with strong currents, which often make it difficult to get from one to another, especially during doldrums. In Darwin's day, the islands all had English names, given them by English sea captains long ago. The islands now have Spanish names, but we will retain the earlier names, since that is what Darwin used.

The location of the Galápagos Islands in relation to continental Ecuador (Wikimedia commons)

The Galápagos Islands are now universally associated with Darwin, and hundreds of thousands of tourists go there every year because Darwin went there, and supposedly generated there the seeds of his theory of evolution by natural selection, of which the Galapagos finches, Darwin's finches, are a textbook example. The reality of Darwin's visit is somewhat different.

Photograph of the Galápagos Islands from a space satellite, with modern names overlaid; in Darwin’s time, San Cristobal was Chatham Island; Floreana was Charles Island, Isabella was Albemarle, and Santiago was James Island (Wikimedia commons)

The Beagle stopped at 4 of the islands: Chatham, Charles, Albemarle (the big one), and James. Darwin spent considerable time ashore at each stop, collecting and recording observations in his diary and notebooks. He was impressed, and depressed, by the dry harshness of the sea-level landscape, but pleased to find that the foliage grew more lush in the central elevations. He did not record in his diary the absence of native mammals, but he clearly noticed it, since he recorded all the kinds of reptiles that were present, especially the marine iguanas, which he called hideous, and the land iguanas, which he also called hideous. He did note that both were unique to the Galápagos. He had much to say about the giant tortoises, which are the dominant large animal and the major food source for humans that live there and for sailors on passing ships.

Marine iguana, Galápagos Islands, recent photograph (Wikimedia commons)

Darwin did not comment much on the land birds, except to record that he found three species of mocking thrushes on 3 different islands. He did not notice that the tortoises varied from island to island, until an English resident pointed that out to him. And while he collected a number of what turned out to be ground finches, he did not know what they were, at the time, and often did not record which island they came from. He wrote nothing in his diary during his Galápagos stay that sounds like a proto-evolutionary thought.

The Beagle left the Galápagos on Oct 19, 1835, and Darwin was back home within a year. He moved to London and farmed out his many specimens to experts, and the birds went to John Gould at the British Museum. It was Gould who pointed out that of the 26 species of land birds brought back from the Galápagos, 13 were ground finches, and all were new to ornithology.

A sketch of the varying beak structure of Galapagos finches, a diagram often reproduced in discussions of Darwin’s finches, but not published until the second edition of his Journal of Reseaches, p. 379, 1845 (Linda Hall Library)

Darwin may not have seen the significance of the finch population in the Galápagos while he was there, but he certainly did after Gould had identified his birds. By the time he came to write his Journal and Remarks, the published form of his diary, for Robert Fitzroy’s Voyages (1839), the finches occupied a much more prominent role. He was not yet ready to say that the Galapagos finches had descended and varied from a few finch ancestors blown to the islands from Ecuador, but with hindsight, you can see that he was now entertaining the idea. He was, by 1839, well on the road to The Origin of Species (1859), even though it would take him another 20 years to work it all out. The Galápagos Islands were indeed crucial for the development of his theory, even if it took a few years gestation, and some help from colleagues, to put his thoughts in order.

Portrait of Charles Darwin, by George Richmond, 1840 (Wikimedia commons)

There are no portraits of Darwin that date from the years of the Beagle voyage. The best we can do is show his wedding portrait, made four years after his return, by George Richmond (last image).

For more on Darwin, see our posts on (in order of appearance): the publication of the Origin, his funeral, his portraits, his work on barnacles, and his 1858 paper with A.R. Wallace.

William B. Ashworth, Jr., Consultant for the History of Science, Linda Hall Library and Associate Professor emeritus, Department of History, University of Missouri-Kansas City. Comments or corrections are welcome; please direct to ashworthw@umkc.edu