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Portrait of Charles Darwin (J. Cameron)

The Evolution of Charles Darwin

A creationist when he visited the Galápagos Islands, Darwin grasped the significance of the unique wildlife he found there only after he returned to London

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(Continued from page 2)

On October 17, Darwin and his four Santiago companions reboarded the Beagle with their week’s haul of specimens. The ship spent the next two days completing a survey of the two northernmost islands and then, 36 days after arriving in the archipelago (during which he spent 19 days on land), the Beagle sailed for Tahiti. Although Darwin did not yet fully appreciate it, a revolution in science had begun.

Following in Darwin’s path, one understands hardships that he overcame that are not readily apparent to readers of his publications. Trekking in the Galápagos, everything is dictated by how much water one can carry, which limits each excursion to about three days—or, for longer excursions, requires stashing food and water along a route.

To Darwin, such logistics would have been even more problematic, as he did not have the lightweight equipment, such as aluminum-frame backpacks and plastic water containers, that we have today. Assisted by his servant, Darwin would have brought his geological hammer, a clinometer for measuring inclines, a shotgun for collecting birds, a compass, plant presses, rodent traps, specimen bottles, spirits of wine for preserving invertebrates, a notebook, a sleeping bag, food and, of course, water. With a characteristic understatement (reflecting perhaps his excellent physical conditioning after extensive fieldwork in South America during the previous four years), Darwin wrote of the 3,000-foot climb to the summit of Santiago merely that the walk was “a long one.” During our own climb along this route in 2004, when we were all packing about 70 pounds, one of my expedition companions was so overcome with heat exhaustion that he had to return to our base camp in Buccaneer Cove; another sprained his ankle on the treacherous footing but managed to keep going.

During a previous expedition, I and five companions came to appreciate, much more vividly than we would have liked, Darwin’s comparison of Galápagos lava flows to an imagined scene from the “Infernal regions.” We were on Santiago, where Darwin had camped for nine days, on our way to a region where tortoises could sometimes be found. Our two guides had suggested a shortcut across a coastal lava flow. What none of us could see from the vantage point of our boat’s landing site was that our route involved more than eight miles of almost continuous lava rock—not just the mile or two that our guides had led us to expect. As we began our trek across this perilous field of jagged lava, we had no idea how close to death we would all come. What was supposed to be a 6-hour excursion became a 51-hour nightmare as we climbed over jumbled piles of blocks with razor-sharp edges, and in and out of steep ravines formed by meandering lavas and collapsed lava domes. Such flows, commented Darwin, who ventured onto several smaller ones, were like “a sea petrified in its most boisterous moments.” He added, “Nothing can be imagined more rough or horrid.”

During our second day on that Santiago lava flow, our water ran out. To make matters worse, our two guides had failed to bring any water of their own and were drinking ours. By the afternoon of the third day we were all severely dehydrated and were forced to abandon most of our equipment. In desperation, our guides hacked off a candelabra cactus branch, and we resorted to drinking the juice, which was so bitter that I retched. Before we finally made it to the coast, where a support vessel was frantically looking for us, one member of the expedition was delirious and close to death. He was subsequently hospitalized for five days, back in the United States, and it took him more than a month to recover.

On another occasion I accompanied Charles Darwin Research Station botanist Alan Tye on a search for the rare Lecocarpus shrub, which Darwin had collected in 1835. A member of the daisy family, the plant had not been seen by anyone in a century, causing some botanists to question Darwin’s reported locality. The day was unusually hot, and Tye, after a few hours of hiking, felt the onset of heat exhaustion and asked me to take over the lead. Using a machete to help clear our way through the brush, I too became heat exhausted, and began to vomit. Heat exhaustion turned out to be the least of my problems. I had inadvertently cut the branch of an overhanging manzanillo tree, whose apples are poison to humans but beloved by tortoises. Some of the tree’s sap had gotten onto a wristband I was wearing and then into both of my eyes. The sting from the sap was almost unbearable, and dousing my eyes with water did nothing to help. For the next seven hours I was nearly blinded and could open my eyes for only a few seconds at a time. As I walked back to our campsite, five hours away, I often had to balance, with my eyes shut, on huge boulders in a dry riverbed, and on the edge of lava ravines. Those were the most painful seven hours I have ever spent. Fortunately, Tye and I did find the rare plant we had been seeking, resolving a century-old mystery and establishing that San Cristóbal has two different members of the same Lecocarpus genus.

Darwin personally reported no untoward physical difficulties during his own Galápagos visit, although he and four companions on Santiago did complain about a shortage of fresh water and the oppressive heat, which reached 137 degrees Fahrenheit (the maximum on their thermometer), as measured in the sandy soil outside their tent. Darwin was twice reminded of the potentially lethal outcome of any excursion into the Galápagos wilds. The Beagle’s crew encountered one lost soul, from the American whaler Hydaspy, who had become stranded on Española, and this stroke of good fortune saved his life. Also, Captain FitzRoy recorded that another sailor from an American whaler had gone missing and that the whaler’s crew was out looking for him. One should not be surprised, then, that, while he was engaged in fieldwork, Darwin would have focused his attention substantially on surviving the many hazards of the Galápagos.

Legend has it that Darwin was converted to the theory of evolution, eureka-like, during his visit to the islands. How could he not have been? In retrospect, the evidence for evolution seems so compelling. Darwin tells us in his Journal of Researches, first published in 1839, that his fascination with the “mystery of mysteries”—the origin of new species—was first aroused by a chance discussion on Floreana with Nicholas Lawson, the vice governor of the islands. Based in part on differences in the shape of a tortoise’s shell, Lawson claimed that “he could at once tell from which island any one was brought.” Darwin also noticed that the mockingbirds seemed to be either separate varieties or species on the four islands he visited. If true, he speculated, “such facts would undermine the stability of Species”—the fundamental tenet of creationism, which held that all species had been created in their present, immutable forms.

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