Reflections on Charles Darwin and his enduring legacy

By Paul A. Johnsgard

Feb. 12, 1809, was a day when fortune shone upon this earth, for on that day two babies were born who were destined to become world famous, and whose lives would have lasting repercussions on subsequent world history. One was born to a poor family of frontier farmers in Kentucky and the other to a prosperous upper-class English family. Both would eventually be forced into taking actions and expressing ideas that at the time were both highly controversial, if not dangerous.

Abraham Lincoln, with the stroke of a pen, would free America forever from slavery, and, furthermore, set the stage for shaping a country in which any citizen, regardless of skin color, might aspire to the highest offices of our land. He thereby challenged its people into eventually accepting the concept that indeed all men and women are created equal, as our Constitution had originally promised.

Charles Darwin, over a lifetime of thoughtful research and writing, freed the world from a blind belief in an omnipotent and often tyrannical god, and provided a theoretic mechanism for answering basic questions about the biological position of humans in the world, and how both plants and animals can adapt and evolve over time to changing physical and biological environments.

Just as Lincoln’s life is inexorably associated with our Civil War, Darwin’s is similarly entwined with natural selection and evolutionary theory. Mention the word “Galápagos” and most biologists would immediately think of Charles Darwin’s 1835 visit as a naturalist during the British oceanic expedition of the HMS Beagle, and his subsequent discovery of the significance of local geographic variations among related but isolated animal populations. Twenty-four years later these seminal observations would become crystallized in his theory of evolution through natural selection, as outlined in his epochal 1859 book, “The Origin of Species.”

Charles Darwin was 22 years old and a recent Cambridge graduate when he boarded the HMS Beagle, a 90-foot British brigantine with a crew of 70, to do hydrographic work around the world. He paid 50 English pounds annually for the opportunity to join Capt. Robert Fitzroy’s crew as a naturalist on an exploratory and hydrographic circumnavigation of the world. The Beagle left England on Nov. 23, 1831, and returned Oct. 2, 1836. Over the five weeks spent in the Galápagos archipelago, during September and October of 1835, Darwin was able to visit only four islands, including Chatham (now officially known as San Cristobal), Charles (now Floreana), Albemarle (now Isabela) and James (now Santiago).

While there, Darwin observed three of the four currently recognized Galápagos species of mockingbirds, and noticed that marked plumage and beak differences occurred among different islands. He further noted that many Galápagos birds are both smaller and more dusky-colored than are mainland relatives. These observations later became important in his analyses of regional variations within and between species.

Additionally, Darwin collected 15 kinds of marine fish in the Galápagos region, all of which were new species. He also obtained 16 kinds of land snails, 15 of which were later found to be unique to the islands. Of 25 beetles he collected, several represented new genera.

Darwin likewise collected plant specimens from all of the islands that he visited. These totaled more than 200 specimens and represented nearly 200 species, including 71 specimens from Santa Cruz, 68 from Floreana, 44 from Isabela and 32 from San Cristobal. Joseph Dalton Hooker, director of Kew Gardens from 1865 to 1885, later described 80 percent of these plants as new to science. A high proportion of the plants also proved to be unique to the archipelago, but many had near relatives in South America. This combination of organisms exhibiting small variations among populations of nearby but isolated islands, but also showing broader biological similarities to those found on a more distant continental mainland, began to shake Darwin’s acceptance of belief in a special divine creation for all living beings.

Darwin also climbed and studied several volcanic peaks (one major peak was later named after him, as also was one of the smaller islands). He counted 60 volcanic cones on San Cristobal Island and estimated that 2,000 might occur over the entire archipelago. He concluded that the entire archipelago is volcanic, and its islands rose from the ocean in relatively recent times, after which they became gradually colonized by both plants and animals. Now we know that the oldest of these islands are only about five million years old and the youngest emerged only about a million years ago, supporting the idea of a dynamic, ever-changing earth, rather than one that had been created once and was thereafter fixed in its final form.

A chance comment to Darwin by Nicholas Lawson, the acting English vice-governor of the islands, to the effect that one can deduce from which island a tortoise originates by its dorsal shell shape, scale pattern and size, had a lasting effect. It was this singular observation, and the fact that Darwin had already been intrigued by the plumage and beak variations among the three species of mockingbirds he had collected, that evidently triggered Darwin’s speculations as to the possible significance of such seemingly inexplicable biological variability in a small group of islands.

In retrospective notes made during the long voyage home, Darwin noted that these inter-island tortoise shell variations and the inter-island beak and plumage variations existing among Galápagos mockingbirds raised questions as to the possible biological significance of such structural differences. Darwin also observed in his Galápagos notes that some small finch-like birds that he had also collected exhibited a “perfectly graduated series in the size of their beaks,” the significance of which would only later become apparent to him. But by then he had already realized that the very existence of such within-species variations in nature might undermine long-held concepts of species immutability and special creation

It was not until his return to England, and the Zoological Society’s ornithologist John Gould had studied his collection of 37 Galápagos birds, that the real significance of the Galápagos materials became apparent. Of 26 land bird specimens, Gould determined that 25 belonged to new species unique to the Galápagos and that three of 11 seabird specimens were similarly of previously unknown species. Gould and Darwin also realized that many of the unique Galápagos birds showed strong similarities to those occurring on the South American mainland. Of the finch-like birds Darwin brought back from the Galápagos, Gould recognized that the sample consisted of a unique group of a dozen or more related finch species.

The biological importance of the Galápagos finches would become fully apparent years later. Darwin first commented in detail on these finches (much later named “Darwin’s finches” in his honor) in the 1845 edition of his journal documenting the voyage of the Beagle. Darwin then sagely noted that from their diverse beak structures one might imagine that “from an original paucity of birds in this archipelago, one species had been taken and modified for different ends.” This basic evolutionary (and revolutionary) idea was to be gradually expanded and its theoretical basis explained over the next 14 years by Darwin’s theory of species modification through the mechanism of natural selection. In 1859, under pressure from friends, Darwin reluctantly published “The Origin of Species,” providing the foundation of modern biology. It has since never gone out of print. He also wrote 14 other books or monographs, nearly all dealing with evolution and natural selection.

Charles Darwin could not have realized the potential that the Galápagos Islands offered for the study of biology when he first set foot on San Cristobal more than 170 years ago, or how his resulting observations and ideas would shape all of modern biology. Like Newton’s once insignificant but now immortal apple tree, and Mendel’s humble monastery garden, the Galápagos Islands will forever be famously associated with Darwin and his prescient observations there. It seems likely that Darwin himself would not have asked for any more lasting recognition than this. Yet, in these islands alone, a volcano, an entire island and a biological station have all been named in Darwin’s honor, in addition to a subfamily of birds as well as a genus (Darwiniothmnus) and several species of plants.

Any biologist is likely to dream of someday visiting the Galápagos, if only because it is the birthplace of modern evolutionary biology. It is also one of the few places in the world that has been only slightly changed since Darwin set foot on these islands almost two centuries ago, with 95 percent of its flora and fauna still surviving. Marine iguanas still cluster in seemingly countless droves on the lava shores of Fernandina Island, mockingbirds still fearlessly approach tourists, and a few giant land tortoises can still be seen wandering freely on the highlands of Santa Cruz. Nearly all the major animal and plant species that Darwin encountered are still to be found there, although a few populations of giant tortoises have become extinct, and all are quite rare.

As the 200th anniversary of his birth and the 150th anniversary of his “Origin of Species” approaches, biologists and scientists worldwide will pause and celebrate the lasting effects that Charles Darwin has had on science, and especially on our understanding of the natural world. In a similar way, the shadow and influence of Abraham Lincoln has grown ever larger since his death; especially as to the importance of his leadership in guiding our nation through the Civil War, and in starting the long road to racial equality in America.

At the same time that the city of Lincoln will be celebrating Lincoln’s birthday on Feb. 12, the University of Nebraska-Lincoln will likewise celebrate Darwin’s birthday. “Cele­brating Darwin’s Legacy: Evolution in the Galápagos Islands and the Great Plains,” an exhibition of photographs, drawings, paintings and Darwinian materials, will be shown at the Great Plains Art Museum from Feb. 12 through March 29, with an opening reception from 5–7 p.m. on Feb. 12.

George Levine, professor emeritus of English at Rutgers University, will present a lecture, “Darwin’s Prophetic Apprenticeship on the Beagle Voyage,” at 7:30 p.m., Feb. 13, at the Nebraska Union, 14th and R Streets, Lincoln, Neb. Dr. Levine’s book, “Darwin Loves You: Natural Selection and the Re-Enchantment of the World,” argues that, rather than providing a disenchanting vision of nature and a diminished view of ourselves, an understanding of natural selection offers instead a viewpoint of enchantment over the natural world’s values and wonders.

On March 26-28, the Center for Great Plains Studies presents a three-day symposium, “Celebrating Darwin’s Legacy,” in the Nebraska Union on the University of Nebraska–Lincoln campus, where 10 invited keynote speakers will present special lectures.

From January through March, five university departments will sponsor special lectures that are open to the university community as well as the general public. In addition, local, middle and high schools are invited to contact 15 UNL faculty and graduate students who will offer presentations on their research activities. Love Library will also have a selection of books related to Darwin and Darwinian biology on display, and the Nebraska State Museum has a permanent exhibit called “Explore Evolution,” featuring evolution, natural selection and Charles Darwin, and current evolutionary research.

For more information about the UNL events, contact the Center for Great Plains Studies at 402-472-3965 or visit the Web site, www.unl.edu/plains.

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