July 19, 2002
The Galápagos Islands are located in the Pacific Ocean 600 miles west of the mainland of Ecuador. The archipelago consists of 13 major islands, 6 smaller islands, and a numerous islets and rocks straddling the equator. The first recorded discovery of the islands was in 1535, when the Bishop of Panama, Fray Tomás de Berlanga, and his ship were carried westward by the ocean currents while on a journey to what is now Peru from Panama. In his account of the islands, written to Carlos V, King of Spain, are included the first documented description of the giant tortoises and iguanas. He also commented on the curious naivetéof the birds "...many birds like those of Spain, but so silly that they do not know how to flee and many were caught in the hand". (fintro.htm 1996) It wasn't until 1570 that the island first appeared on a map. The islands were called "Insulae de los Galápagos -- Islands of the Tortoises." They were also called the "Encantadas" (Bewitched Islands) because of the way in which the strong and variable currents made navigation difficult. During the late 1500s to the early 1700s, pirates frequented the Galápagos as a refuge and base for their raids on the Spanish colonial ports. They used the island to stock up on water and tortoise meat. Many other prominent seamen visited the enchanted isles during the 1600 and 1700 bringing with them lucrative whaling and fur industries the Galápagos were prime to fuel. Of the many travelers it hosted, all but a few held the same view of the islands as Captain George Vancouver's, captain of the HMS Discovery, crew, "the most dreary barren and desolate country I ever beheld- nothing but large Cinder without any sign of Verdure or vegetation". (fintro.htm 1996)
Upon his arrival to the islands, Charles Darwin, a bright young naturalist aboard the HMS Beagle shared a view of the Galápagos expressed by many before him and after, as he put it "Nothing could be less inviting than the first appearance. A broken field of black basaltic lava is everywhere covered by a stunted brushwood which shows little signs of life,".(Darwin 1839) Charles Darwin arrived in the Galápagos Islands on September 15, 1835, for of a 5 week stay to replenish the rations of the HMS Beagle. He had embarked from England in 1833 on a five year expedition serving as a naturalist aboard the ship in the hopes of furthering his natural history training while collecting scientific data that would prove the validity of creationism. (Marks 1991) His original intentions could not have been farther from the fate that awaited him on that voyage. While in the Galápagos Darwin only visited 4 of the islands, San Cristóbal, Floreana, Isabela, and Santiago from which he made an extensive collection of plants, and animals, as well as observations about their natural history.
Concerning the islands vegetation Darwin remarked, "Although I diligently tried to collect as many plants as possible, I succeeded in getting only ten kinds: and such wretched ooking little weeds would have better become artic, than an equatorial Flora." (Darwin 1839) Darwin had no concept of what the data he collected in the Galápagos would later mean to the world. Darwin's five week jaunt to the Galápagos Islands set in motion the unstoppable force of human imagination and curiosity that would lead him to question his faith and the very dictates of contemporary science. The abundant life he saw there, coupled with data from South America and other ecological observations made along his voyage on the HMS Beagle, would provide him with the necessary evidence to make some of the boldest and far-reaching proposals of modern science. Put best by Robert Bowman, the current dean of Galápagos researchers, "No area on Earth of comparable size has inspired more fundamental changes in Man's perspective of himself and his environment than the Galápagos Islands, -the unconventional flow of nature on the land and the sea has spawned revolutionary views on the origin, not only of species, but also of life itself." (Bowman 1984)
It has been extensively debated how great a role the Galápagosand the animals Charles Darwin found there played in the formulation of Darwin's theories of natural selection and evolution. Many scientists argue that it little mention in his Origin of Species and thus played only a marginal role the development of his theories. (Gould 2002) While others contest this claiming that the Galápagos Islands were the birth place of modern evolutionary theory. Only Charles Darwin himself knows how profound an effect the specimens and observations collected on his brief stay in the GalápagosIslands had on his revolutionary theories.
Regardless of the role the islands played in Darwin's theories, his observations and their scientific significance as a record of the Galápagos as a microcosm of evolution can't be denied. Through his observations and the research of many other prominent scientists the Galápagos have given the scientific community a glimpse into nature's regenerative cycle of evolution. It was not Darwin, the Grant's, and William Beebe that made famous the enchanted isles of the Galápagos but the Galápagos themselves that inspired greatness in the minds of these and many scientists to come.
After having been aboard the HMS Beagle for nearly three and a half years before ever reaching the Galápagos Islands, Charles Darwin was growing weary of his sea going adventure and longed for the homely shores of England. Despite his desire to be rid of South America and her taunting coastline he looked forward to his visit to the Galápagos with anticipation and hope, exclaiming "I am very anxious for the Galápagos Islands , -I think both the geology & Zoology cannot fail to be very interesting," in a letter to his sister Caroline in England. He was sorely disappointed. He had hoped it to be a fiery furnace of geological upheaval and creation; needless to say the islands relatively inactive volcanoes did not impress him.
Darwin saw in the island's geology Lyell's Principles of Geology at work. It was Lyell's theory that past geological processes acted much like those of the present gradually shaping the earth's features. Lyell refuted the idea that species behaved in much the same way, organic life was immutable existing continually throughout geologic time, individual species appeared and disappeared with time. He rejected the concept of species evolving into other species due to a direct response in environmental conditions. Darwin accepted Lyell's view on organic existence, the occasional creation of species, their gradual spread to suitable habitats and their eventual extinction due to environmental change. It wasn't until Darwin began to examine the biological diversity of the islands that he would find evidence to the contrary. Starting on the second day of their stay in the Galápagos Darwin began filling his diary with lengthy and detailed accounts of the animals he saw all around him, his interest quickly turned from geology to zoology. (Larson 2001)
It was Darwin's desire to make the most of his limited time in the island and create the most comprehensive collection of flora and fauna possible and to a great extent he succeeded. All of the specimens he obtained came from 4 different island in the archipelago Floreana, Isabela, Santiago, and San Cristóbal. Darwin was able to collect specimens from the interior highlands of both Santiago and San Cristóbal Island. No previous collector had braved the interior and up to that point only island arid coastal regions had been even remotely taxonomically documented. Darwin's collection was the most complete comprehensive collection of Galápagos birds, reptiles, insects, fish, sea mammals, and plants taken form the archipelago at that time. (Larson 2001)
He took note that there were little if any land mammals, minus two species of rat, which he dismissed as most likely being intrusive and introduced as opposed to being endemic. The mass variety of animals he encountered were reptiles and birds. These observations seemed to support Lyellian creationism, the belief that all species had a single pair center of origin from which they radiated. It made sense that reptiles would be able to colonize the islands more easily from either a center with in the islands or on the mainland then larger land mammals would. Reptiles and bird could much more easily traverse long distances of water to find new habitats. Following this view Darwin did not pay special to the diversity and varieties of individual species between islands. Rather he assumed that since the islands had fairly homogeneous habitats any fitting species would spread throughout the islands with ease. Darwin also preformed numerous crude experiments while on the islands. Most of these experiments focused on the native animals "tameness" and obliviousness to humans. He would chase and harass sea lion marine iguanas and any and all birds ceaselessly. He attributed the animal naivetéto lack of predators and predicted that over time with the introduction of humans that these animals would develop or evolve an instinctual fear of humans.
Darwin left the Galápagos a creationist, it was not until reviewing his copious notes, observations, and collected specimens that he began to doubt the validity of his beliefs. During the year long voyage back to England Darwin focused his attention mainly on the relationships of mocking birds in the archipelago. He had a specimen from each of the 4 islands and two where seemingly the same while the other two were markedly different. Considering that the habitats of all 4 birds were relatively similar according to Lyell's theory the birds should not have marked different features. If the different mocking birds were indeed different species these difference would be of great significance. Similarly, Darwin recalled that locals living on the islands could easily distinguish what island a tortuous came from based on the distinct markings of its shell. According to Lyell each species was able to accommodate themselves to a certain extent to a change in external circumstances, but the differences among species that Darwin observed existed within a small homogenous community. Darwin found the answer to his questions in Lyell's explanation of variety within a species. Despite this supposed explanation a seed of doubt had been plant in Darwin's mind. It was this seed that grew into today's modern evolutionary theory.
Once back in England Darwin turned over the bulk of his collection to the Zoological Society of London. In particular the eminent ornithologist John Gould was one of the many scientists that cumulatively identified the specimens of Darwin's collection. Gould identified over 14 new species of ground finches endemic to the Galápagos , he also remarked "that their [the finches] principle peculiarity consisted in the bill presenting several distinct modifications of form."(Larson 2001) This new evidence about the Galápagos finches, many of which Darwin had not even recognized as finches, lead him to ponder the viability of species evolving through accumulated variations. There was no other explanation as to why so many similar species would exist in such a small area except that they had all evolved from a common ancestor. The problem with this proposal was that such evolution required isolation and since he had not recorded from which islands he had collected each of the finches, the finches themselves provided no basis for such a claim. With out isolation the there could be no speciation due to the possibility of interbreeding. Darwin tired in vain to reconstruct the source of the finches but could not provide undisputable evidence for their geographic isolation. As a result Darwin was never able to use the example of the finches as evidence for evolution in any of his published writings, rather it simply brought to light an interesting divergence to the current accepted theories of species origin.
This divergence received even great thought after Gould confirmed that three of the mocking birds that Darwin had collected were in fact different species. Darwin knew that the different species were geographically isolated, each being from a different island. The mocking birds provided him with evidence of transmutation, the change of one species to another through cumulative collection of variations caused by differing environmental pressures. In his early journals of transmutation Darwin identified the "species on [the] Galápagos Archipelago" as the primary source "of all my views." (Larson 2001) It served as the ideal test case and it distinct species provided his best evidence. Darwin concluded that most of the animals in the islands were new individual species, yet at the same time closely related to those of the mainland. Also that among the islands, all with similar habitats existed distinct species of birds, which varied from island to island. It was clear to Darwin that the Galápagos and its inhabitants represented the evolution of species but by what mechanism he was not sure. (Whitfield 1993) Using the same logic expressed by Thomas Malthus in his essay An Essay on the Principle of Population, Darwin derived his theory of natural selection. (Whitfield 1993) That like people, animals produced an excess of offspring and that each species population is kept in check by certain limiting factors such as availability of resources often causing disease and famine. These limiting environmental factors or wedgings selected against the weak and ill adapted animals favoring those with variations which allowed them greater success at surviving. The individuals with these variations would survive to pass the advantageous variations to their offspring and in time a population could evolve into a better adapted species. In 1838 Darwin wrote in one of his many notebooks on the subject, "The final cause of all these wedgings, must be to sort out proper structure & adapt it to change." (Larson 2001) He now had the physical evidence of evolution and its cause. In 1846 Darwin concluded in a journal and to a colleague,
"- the circumstance, that several of the [Galapagos] islands possess their own species of tortoises, mocking-thrush, finches, and numerous plants- that strikes me with wonder- [This] little world within itself, or rather, a satellite
attached to America, whence it ha derived a few stray colonists- we seem to be brought somewhat near to the great fact ñ that mystery of mysteries - the first appearance of new beings on this earth. The Galápagos seems a perennial source of new things." (Larson 2001)
Darwin mulled over his ideas producing a myriad of examples as evidence of evolution by natural selection. He kept his revolutionary ideas a secret understanding the grave implications they would have on modern science and religion. He continued to gain esteem as a gentleman scientist publishing numerous essays on varying subjects of natural history, citing his observations from the Galápagos in many. It was not until prompted by the threat of Alfred Russel Wallace publishing his independently derived theory of evolution that closely coincided with his own that Darwin sought to publish his cumulative theory of evolution. Published a year later in 1859 On the Origin of Species by Means of Natural Selection was the abstract of his theory of evolution by natural selection. It sent shockwaves through the scientific community and was ultimately accepted to be the evolutionary truth on which modern life science is based.
The Galapagos's contribution to science didn't stop with Darwin and the observations he made there. After his theories gained fame many scientists decided to see for themselves what inspiration the Galápagos had to offer. In 1869 Dr. Simon Habel offered his extensive collection of over 300 specimens, representing over 70 species of Galápagos bird to the Zoological Society of London. He had visited seven different islands in the Galápagos but only collected specimens from three, two of which had never been visited by naturalists at the time. The British ornithologist Philip Lutley Sclater and his colleague Osbert Salvin leaped on the opportunity to use Habel's collection to expound his own scientific endeavors of classifying the Earth into biographic regions while support Darwin's theory that geographic isolation breeds species. Their final report spoke with confidence:
"The birds that are now found [on the Galápagos], being related to American birds, must have emigrated thence became surrounded. The oldest immigrants seem to be indicated by their generic difference from their continental allies, the more modern comer by their merely specific distinctness, and the most recent by their identity with birds now found on the adjoining continent." (Larson 2001)
In 1874 Albert Gunther the British Museum Keeper of Zoology did extensive research on Galápagos tortoises and their remains. He concluded that the tortoises once thought to have a single species brought to the islands by sailors, was indeed "a multiplicity of species," each species from a different island, providing further proof a speciation due to isolation. (Larson 2001) Many other scientist and naturalists studied and collected in the Galápagos Islands up until the early 1900's in an effort to both prove and disprove Darwinian evolution.
Gunther, Sclater, and Salvin were only a few among the many scientists that indulged themselves in "Galápagos Science". Many notable scientist and naturalists like Walter Rothschild, George Baur, Louis Agassiz, David Starr Jordan to name a few centered their research around the natural history and present forces of evolution in the Galápagos Islands. (Larson 2001)
During the early 1900's there were many expeditions to the Galápagos to collect specimens for research and for displays in sponsoring museums. One such trip, lead by William Beebe, in 1923 not only collected organisms for specimens but plenty of film and photographs. (Welker 1975) The expedition only spent 4 days in the islands out of it's total eleven week tour. Beebe recounted the journey in Galápagos: World's End. Beebe undertook another expedition to the Galápagos in 1925 on the Arcturus. His second voyage spent more time on the open ocean than it did on the island of the archipelago making only a few brief visits to shore. The expedition made headlines, as the ship was in constant communication with the mainland. Beebe wrote a series of articles about the expedition to be published in the Sunday edition of the New York Times. (Welkner 1975) These articles were the basis of his book detailing the expedition The Arcturus Adventure. In one of his many articles Beebe described research he conducted underwater with the use of a diving helmet. "As I peer out through my little rectangular windows I seem to be actually living an experience which only the genius of a Verne or Wells can imagine into words- I have even the sensations of a god." he wrote. (Beebe 1926) Beebe claimed to have been the first person to use such an apparatus for scientific research, a claim that brought about a public rebuke by a colleague whom published research based on the technique six years prior. (Larson 2001) Beebe was prone to such exaggerations in his writings, and his published travelogues The Arcturus Adventure and Galápagos: World's End were no exception. In the second of his books he recounts the eruption of a volcano and the treacherous hike and near death experience of his attempt to see the phenomena up-close for the sake of science. "Baked from above and below, we staggered on, unable to sit down and rest for the intolerable heat of the rocks." (Beebe 1926) He also claimed that the eruption he witnessed was the "first known to man" on the Galápagos Islands despite earlier reports on volcanic eruptions with in the islands. Both of Beebe's expeditions to the Galápagos accomplished little in the way of science, their only real contribution being some new species specimens, its most notable that of a living flightless Cormorant. (Welkner 1975) Despite the questionable accuracy of his accounts and their lack of scientific value Beebe's esteemed reputation came from his ability to convey science to the modern man. His books were best sellers, and he even elevated the Galápagos to the best sellers list with Galápagos: World's End in 1924. Though his theories were weak, inconsistent, and lacking of support Beebe sparked a great deal of interest in the Enchanted Isles, bringing to the islands many passing ships and even some colorful colonists like the German philosopher, Dr. Friedrich Karl Ritter, his mistress, Dore Strauch Koerwin from Berlin, Heinz and Margaret Wittmer from Cologne, the self-proclaimed "Empress of the Galápagos ", Baroness Eloisa von Wagner Bosquet, and her three lovers. (fintro.htm 1996)
Today Darwin's theory of evolution by natural selection is widely accepted as the governing law of life on this planet. Even after over a hundred years the Galápagos Islands are still considered evolutions haven. In 1973 the Grants, Peter, a professor in Canada at McGill's University and his wife Rosemary began the research of Darwin's Finches that would become their life long career. Peter Grant had already achieved international notoriety for his field studies on the role of competition in the evolution of birds and rodents. (Larson 2001) The Grants hoped to test the role of the physical environment in shaping species, and found that Darwin's finches were the most suitable group of island birds for addressing these issues. The finches were highly variable, easy to handle live and found in varying combinations largely undisturbed by humans. (Weiner 1994) In the first year they, along with the Abotts, studied Galápagos ground finches at eight widely scattered sites on seven different islands, including the small island Daphne Major. At each site they inventoried seeds and fruit, weighed and measured a random sample of netted finches and observed which species ate what food. They spent three months collecting date during the rainy season and two months collecting data for the dry season. They Grants saw evidence of interspecific competition, noting that the beaks of finches on islands with more then on species of finch expressed a greater degree of modification then those form different islands. Only species that feed of different food sources, for example large seed and small seed could co-exist, two species feeding on the same type of seed would be in competition, with one species wiping out and replacing the other. Grant's team had found a predictable pattern of evolution among Galápagos ground finches. They documented significant differences in food supply and feeding behavior among the finches to account for the divergence of beak sizes and shapes. Big-beaked ground finches ate larger, harder seeds and lived only where such food grew in abundance, while small-beaked ground finches ate the widely available smaller softer seeds. (Weiner 1994)
The Grants continued to return to the Galápagos as El Niño and La Niña brought drought and markedly altered long term weather patterns affect food supply. The Grants hoped to show that directional selection would occur as a result of changes in food supply. The Grant's limited their permanent study to the island of Daphne Major, a small undisturbed islet with the two most similar species of ground finch. From 1975 on the Grants measured, weighed, and banded these birds and their descendants. By having detailed data on the individual finches on the island and their descendents the Grant's were able to observe the heritability of beak and body size. Through careful data collection of the population on Daphne Major over the past twenty years the Grant's have observed dramatic examples of recent speciation and adaptive diversification with current species. They have evidence of interspecific competition and natural selection acting on contemporary populations producing observable and measurable evolutionary changes. As Peter Grant tells his classes at Princeton, "Evolution happens the whole time." his research bears witness to the fact that evolution is constantly and observably happening in our life time. (Weiner 1994)
The Galápagos Islands, those seemingly lifeless and desolate islands, described so mercilessly by Melville as "an incomputable host of fiends, ant-eaters, man-haters, and salamanders." has been the inspiration of modern evolutionary theory for the past one hundred and seventy years. (Larson 2001) It is a place abounding with flora and fauna all its own; a veritable microcosm of evolution in action. It has a great scientific history which by no means ended with the historical observations and conclusions of Charles Darwin. Today it is has important to sciences understanding of life as it was when Darwin first conceived the faintest notion of the possibility of evolution. The information that can be obtained by the study and observation of this archipelago is by no means limited to its surfaces, as even its waters teem with peculiar life wanting to be discovered. It is the duty of the modern world to protect the Galápagos Islands, as a legacy, and as a tool to the continuing pursuit to those questions that drive us all: Why are we here? How did we become? and Where are we going?
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Grant, Peter R. and Grant, B. Rosemary. Evolutionary Dynamics of a Natural Population: The Large Cactus Finch of the Galápagos. Chicago, The University of Chicago Press. 1989.
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