Selections from Celebrating Darwin’s Legacy: Evolution in the Galápagos Islands and the Great Plain

January 29– March 21, 2010 —

In 2009, the Center for Great Plains Studies, Lincoln, Nebraska, premiered an exhibition celebrating the bicentennial of Charles Darwin’s birth and the 150th anniversary of his pinnacle publication, The Origin of Species. Photographic images and handcolored drawings were created on a 2005 observational voyage to the islands by Dr. Paul A. Johnsgard and a team of naturalists: Linda R. Brown, Allison Johnson, Stephen Johnson, and Josef Kren. The Museum of Nebraska Art exhibition features selections from the larger show.

Excerpts from an essay by Dr. Paul A. Johnsgard:

In September of 1835, a 25-year-old British naturalist set foot for the first time on the easternmost island of the Galápagos Archipelago, a group of small and remote volcanic islands straddling the equator and lying about 600 miles west of Ecuador. He was in the third year of a four-year scientific voyage around the world on a British brigantine named the Beagle. Its captain had selected him as a volunteer naturalist for the long trip, whose primary purpose was to map little-known coastlines, especially South America’s. Captain Robert FitzRoy, son of a distinguished family, was then in his late 20s, but was already a rising star in the British Navy. The naturalist was Charles Darwin, who was also from an upper-class English family, the son of a general physician and a nephew of Josiah Wedgewood, head of the famous ceramics firm.

Darwin had just graduated from Cambridge University, but was without immediate future plans. He had received his father’s reluctant permission to join the Beagle only after heartfelt pleadings, and was even required to pay the British Admiralty 500 pounds sterling to cover the anticipated costs of taking him on board. Additionally, Darwin had no prior sea-going experience, suffered greatly from seasickness, and Captain FitzRoy’s initial perception of Darwin’s abilities caused him to doubt that he “could possess sufficient energy and determination for the voyage.” But when Darwin joined the Beagle, he was in the prime of his life, and was trained in geology as well as biology. By the time he reached the Galápagos, Darwin had gained much valuable biological and geological field experience during the nearly three years the Beagle had already spent surveying the coastlines of South America.

As soon as he landed at the Galápagos, Darwin began collecting all the specimens of animals and plants that time allowed. Darwin collected many of the very tame finches that were among the islands’ most common land birds. These were present in all various combinations of drab brown and black plumages, with a confusing array of beak sizes that ranged from delicate and wren- or warbler-like to powerful parrot-like beaks strong enough to crack the hardest seeds. Darwin was clearly unable to make initial sense of all these variables, and at first failed to note from which island he had obtained each of his specimens, thus obscuring any inter-island differences that might have otherwise been evident.

Darwin noted that many Galápagos birds are both smaller and more dusky than mainland relatives, a fact tending to cast doubt on the traditional idea that species have remained unchanged (“immutable”) ever since they were created. He also collected three of the four now-known Galápagos species of mockingbirds, and was immediately impressed by their plumage and bill-shape differences in different islands. The birds did quite closely resemble a species of mockingbird commonly found along the western coast of South America. Darwin had already noticed that birds from islands off the west coast of Africa rather closely resembled those of mainland Africa, as just the Galápagos birds most closely resembled those from mainland South America.

Darwin also collected plant specimens from all four of the islands that he visited. These totaled more than 200 specimens and represented nearly 200 species. A high proportion of these plants proved to be unique to the archipelago, but, like the animals, many had their nearest relatives in South America. Darwin also collected 15 kinds of marine fish in the Galápagos region, all of which were found to represent new species, and obtained 16 kinds of land snails, all but one of which were later also found to be new to science. These many examples of the islands’ unique fauna made Darwin contemplate the possible effects of long-term isolation on a species’ ability to gradually adapt to varied environments, and thereby undergo evolutionary change and gradual divergence from relatives existing elsewhere.

On one of the four islands that Darwin visited, he met with Nicholas Lawson, an English-born Galápagos resident. Nicholas informed Darwin that the local residents could tell from which of the many Galápagos Islands a giant tortoise had originated simply by the unique shape of its shell. These observations on variations in Galápagos birds and reptiles would later become an important aspect of Darwin’s analyses of individual and regional variations within species, as sources of potential differential inherent attributes that could influence their future chances of survival.

On his return to England, Darwin’s bird specimens were turned over to John Gould, taxidermist of the Zoological Society of London. Of the 37 bird specimens Darwin had obtained on the islands, Gould determined that 28 represented previously undescribed species. Of the sparrow-like birds from the Galápagos, Gould soon determined that these birds consisted of a unique group of a dozen or more related finch species. They later became generally known as “Darwin’s finches.”

Darwin’s observations on the animals and plants of the Galápago Islands during the Beagle’s five-week exploration would eventually provide him with some of the first clues he would need in proposing his theory of evolution based on natural selection nearly three decades later, in 1859. This theory would make him world-famous, provide the theoretical foundation for modern biology, and would force the Christian Church to re-assess its basic Bible-based beliefs in such fundamental precepts as the age of the earth, and the idea that species have remained unchanged since their original creation. It would also challenge humans to contemplate our basic mammalian similarities, and the possible ancestral origins of humankind.