The Voyage of the HMS Beagle

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The Voyage of the HMS Beagle

Overview

Charles Darwin (1809-1882) was among the most influential scientists who ever lived. He began his career as a naturalist aboard the HMS Beagle, on its five-year surveying mission around South America and across the Pacific. Darwin's work was to make the Beagle's journey one of the best documented surveys of its time. His observations would eventually result in his theory of evolution by natural selection. This theory holds that species change gradually because individuals best-suited to their environments are more likely to survive, reproduce, and pass their desirable traits to their offspring.

Background

Charles Darwin launched the greatest revolution in the history of biology with his theory of evolution by natural selection. However, like many original thinkers, he did not show extraordinary promise in school. Darwin came from a prominent and wealthy family. His grandfathers were the famous physician Erasmus Darwin (1731-1802) and Josiah Wedgwood (1730-1795), the manufacturer of the fine pottery that bears his name. Erasmus Darwin was a radical freethinker. Wedgwood, a Unitarian, was only slightly more orthodox. Yet their children Robert Darwin and Susannah Wedgwood, who met through their fathers' friendship, led a conventional, upper-class English life, and raised their own family in the established Anglican Church.

Charles Darwin was a born naturalist, and enjoyed tramping around the woods and collecting rocks and insects. Being an outdoorsman was acceptable for a nineteenth-century English gentleman; in particular, hunting was a popular pastime. But science was considered a hobby, not a suitable occupation. At school, the emphasis was on Greek and Latin, and young Darwin was scolded for wasting his time on chemistry experiments.

Given his scientific bent, a medical career seemed like a possibility, and so Darwin was sent to Edinburgh University in 1825. It was several decades before the advent of anesthesia, and watching an operation being performed on a screaming child put an end to his interest in medicine. At that point, Darwin's father Robert decided that the best place for his tender-hearted and somewhat eccentric son was in the Anglican clergy, and sent him to Christ's College at Cambridge.

Darwin was not particularly interested in becoming a clergyman, but neither was he alarmed by the prospect. At the time, many English scientists were clergymen. Gentlemen of independent means were able to arrange for a small country parish and a quiet life that gave them both a respectable occupation and time to indulge their own interests. In any case, Darwin was happy to go to Cambridge. He enjoyed university life. Most of his time was spent socializing, or in the outdoor pursuits he loved: hunting, fishing, and riding horseback. He became fascinated by beetles, and went to great lengths to collect them. He undertook many hiking expeditions with botany professor John Henslow (1796-1861) and geology professor Adam Sedgwick (1854-1913).

At about this time, Darwin had two experiences that greatly influenced the future direction of his thought. The first was a re-reading of a scientific text, Zoonomia, written by his grandfather Erasmus. Erasmus Darwin had noted that animals such as dogs and horses were bred for desired traits, changing the characteristics of their breeds over time. If that were possible, then perhaps many characteristics of species had changed during the course of their history, and possibly a number of species had come from a single root, or "living filament." Charles Darwin was very impressed with his grandfather's ideas, but realized he had been theorizing ahead of the evidence. No facts were presented that directly supported the theories.

While hiking with Sedgwick in Wales, Darwin observed what he considered to be the opposite error. A local workman had discovered the fossilized shell of a tropical mollusk in a nearby gravel pit. Fossils had been known since the seventeenth century; they were thought to be remnants of a time before the biblical flood. The tropical shell fascinated Darwin, but it gave Sedgwick pause. It was impossible, he declared, because Wales was not a tropical place. He seemed annoyed to have encountered something that did not fit into his established theories.

In combination, these experiences molded the way Darwin was to do science. He was wary about theorizing without sufficient evidence, and he recognized the importance of looking carefully at evidence, even (or perhaps, especially) that which seemed anomalous. As a result, he was inclined to collect as much data as possible before beginning to draw conclusions.

The opportunity to do so would arrive unexpectedly. In 1831, Captain Robert FitzRoy of the Royal Navy was about to undertake a surveying trip to South America with his ship the HMS Beagle. He already had hired one naturalist to study the plants, animals, and minerals of the South American coast and the islands nearby. He wanted a second naturalist, one who could afford to pay the expenses of gathering, storing, and shipping his specimens, and who was of the appropriate aristocratic social class to be good company for him. Professor Henslow recommended Darwin, who fit the bill in all respects. A man of orthodox religious beliefs, FitzRoy was especially pleased that Darwin had studied for the clergy. He hoped that he could find evidence that supported the literal truth of the Bible's account of Creation.

Impact

In preparing for his trip, Darwin read the latest works on natural history and geology. One of these was Principles of Geology, by Charles Lyell (1797-1875). Lyell proposed a new explanation for the extinct creatures that appeared in the fossil record. Rather than being evidence of a biblical catastrophe, he wrote, gradual changes in the Earth modified conditions in such a way that some unprepared creatures slowly died out. What most alarmed many of his readers was that this process would take many thousands or even millions of years. This was contrary to religious teachings that the Earth was about 6,000 years old.

Darwin was not by nature a religious iconoclast. He had carefully reviewed the Anglican theology before agreeing to study for the clergy, and found nothing there to object to. Yet Lyell's ideas were interesting to him. And, with his grandfather's book in mind, he took the reasoning one step further. If species were constantly dying out, yet there was still a huge variety of different plants and animals on Earth, new types must have arisen, and be arising still, to replace those that are lost. Was God continuing to intervene with new, separate acts of creation? With these questions in mind, Darwin set off on his journey.

The HMS Beagle was a relatively small wooden sailing vessel, only 90 feet (27 m) long, with 74 people on board. It sailed from Plymouth on December 27, 1831. Darwin was sea-sick throughout the trip, particularly when the weather was bad. The sociable young man was generally able to get along with the opinionated and rather bad-tempered Captain FitzRoy, but relations were occasionally tense. At one point, an argument over slavery, which Darwin opposed, led to his temporary banishment from the captain's table.

When they arrived at the coast of South America, near Salvador, Brazil, most of the crew stayed with the ship gathering survey data. Darwin was free to explore as he chose. The lush forests, full of plants and animals he had never seen before, were like a paradise to him. In general, he worked alone. As was the custom of the time, he studied birds by shooting and collecting them, as many as 80 different species on a single morning. He could accumulate dozens of insect specimens in a day. He found many fossils in Brazil and Argentina. Soon the Beagle began to fill up with Darwin's plants, animals, and rocks, hauled on board by the sackful. His shipmates nicknamed him the "Flycatcher."

Darwin studied, preserved, and labeled his finds, packed them up, and shipped them back to Henslow in England. He took such detailed notes that the voyage of the Beagle was one of the best-documented scientific expeditions of its time. His careful work made his reputation back home. On the ship, his courage and vigor spared him from the scorn sometimes leveled at learned passengers. He took many side trips, such as a journey on horseback across the pampas with South American cowboys, or gauchos. At the southern tip of South America, Tierra del Fuego, Darwin went mountain-climbing. During the course of the voyage, however, his health deteriorated, especially after the bite of a disease-carrying insect left him bedridden for seven weeks.

During the Beagle's years of travels in South America, Darwin gave a great deal of thought to Lyell's ideas about geology and the history of the Earth. Near the Straits of Magellan, he experienced an earthquake, and then noticed that the shape of the land around him had changed. Mussels that were on rocks underwater were now exposed, and left to die. He found fossilized seashells up in the mountains, and discovered a petrified forest at 7,000 feet (2,134 m) above sea level. He uncovered the fossils of prehistoric animals and, near Buenos Aires, the fossilized tooth of a horse. Yet he knew that there had been no horses in South America when the Spanish had arrived and re-introduced them in the sixteenth century. All these discoveries influenced Darwin's ideas about how changes had occurred on the Earth and in animal species.

In 1835, the Beagle sailed from Lima, Peru, on the western coast of South America, to a group of Pacific islands called the Galapagos. The name came from the Spanish word for giant tortoises, which were among the unusual animals Darwin observed there. He noticed that many of the animals and plants were unique to the islands. In fact, there were even many differences between the species on each individual island. The small size of the living community coupled with its geographic isolation made it an ideal laboratory for studying changes in species.

For example, each island had species of small birds called finches. Although these birds all looked similar, their beaks were of different shapes, depending on what type of food was available on the island. The differences were not confined to birds. Some types of lizards could swim well and ate seaweed. Others lived on the land and ate cactus. It seemed clear that, in some way, plants and animal species adapted to their environments.

After the Galapagos, the Beagle continued into the Pacific, visiting Tahiti, New Zealand, and Australia. It then skirted the southern tip of Africa. Off Africa's western coast, on the Cape Verde Islands, Darwin noticed that the animals, though distinct, were similar to those of Africa. He remembered that the distinct species of the Galapagos were more similar to those of South America. Why should these isolated species be the same in general form, but differ in details, from those of a nearby continent?

The Beagle sailed into the port of Falmouth on October 2, 1836. Darwin never left England again. Nor was he ever again in completely good health, although he married and had 10 children, and lived to the age of 73. Within a few years he had published an account of his travels, and then continued to study his data. Darwin, the careful observer, was loath to jump to conclusions. He would sift through his evidence for 20 years before publishing On the Origin of Species, the book that was to change the face of science.

SHERRI CHASIN CALVO