Page 1
Page 2
Page 3
Page 4
Page 5
Page 6
Page 7
Page 8
Page 9
Page 10
Page 11
Page 12
Page 13
Page 14
Page 15
Page 16
Page 17
Page 18
Page 19
Page 20
Page 21
Page 22
Page 23
Page 24
Page 25
Page 26
Page 27
Page 28
Page 29
Page 30
Page 31
Page 32
Page 33
Page 34
Page 35
Page 36
Page 37
Page 38
Page 39
Page 40
Page 41
Page 42
Page 43
Page 44
Page 45
Page 46
Page 47
Page 48
Page 49
Page 50
Page 51
Page 52
Page 53
Page 54
DARWIN A Companion Guide to the Darwin Dinosaurs Exhibit DINOSAURS ABC Museum of Natural History The Darwin Dinosaurs Guide has been reviewed by a number of leading scientists and historians inlcuding Dr. Paul Sereno University of Chicago Dr. Norman MacLeod Natural History Museum London and Dr. John van Wyhe University of Singapore. Version 3.0 March 2015 Image Credits I think... from Darwins notebook Table of Contents page Cambridge University Library Unconformity at Siccar Point opposite page 1 photo by Dr. Clifford E. Ford Duria Antiquior page 6 National Museum of Wales Mary Anning letter page 7 Wellcome Trust photo of Down House page 10 courtesy of Down House Darwin page 11 English Heritage Library H.M.S. Beagle in the Galapagos Islands by John Chancellor page 12 image reproduced courtesy of Gordon Chancellor portraits of Emma and Charles Darwin page 24 English Heritage Library photo of moth page 37 Minden Photos Darwins grave page 39 Getty Images Image of DNA page 40 CORBIS. All other images owned by the author or public domain. Copyright Angus Carroll 2015. All rights reserved. DARWIN DINOSAURS Revolution The New Geology First Dinosaurs Mary Anning Charles Darwin Early Years The Voyage Development of the Theory Origin of Species Later Life Evolution DNA Tree of Life Birds Dinosaurs 1 8 40 unconformity at Siccar Point Scotland. Revolution In 1650 Archbishop James Ussher calculated that God created the world on Sunday October 23 4004 BC. That fit well with established doctrine at the time and it was soon accepted as fact-even added to the King James Bible. By the late eighteenth century however a number of people began to question the simplicity of that explanation based on what they saw around them. One of them was James Hutton. In true Victorian fashion Hutton was many things chemist physician farmer and geologist. He made a number of field trips throughout Scotland in the 1780s examining geological formations at Glen Tilt Siccar Point and Jedburgh and concluded the only way to explain the formations was through long and continuous processes as opposed to catastrophes like the biblical flood and in turn that implied Earth was very old. The New Geology He first presented his ideas to the Royal Society of Edinburgh in 1785 and the society published his dissertationTheory of the Earth three years later. In 1795 he published a much expanded two-volume version that addressed earlier criticisms and provided more evidence. Unfortunately it was virtually unreadable. A typical excerpt The immense time necessarily required for this total destruction of the land must not be opposed to that view of future events which is indicated by the surest facts and most approved principles. Time which measures every thing in our idea and is often deficient to our schemes is to nature endless and as nothing it cannot limit that by which alone it had existence and as the natural course of time which to us seems infinite cannot be bounded by any operation that may have an end the progress of things upon this globe that is the course of nature cannot be limited by time which must proceed in a continual succession. Even in the late eighteenth century that was abstruse. Fortunately for Hutton and posterity his friend John Playfair published Illustrations of the Huttonian Theory of the Earth in 1802 shortly after Huttons death in which Playfair explained Huttons new geology in a more comprehensible form. It is Playfairs book that is generally credited with spreading Huttons ideas Earth was very old the same continuous geological processes that shaped Earth in the past were still active today a theory that would become known as uniformitarianism and the idea that deeper James Hutton The Founder of Modern Geology 1 2 rocks are older as newer sediments the result of erosion and other continuous processes are deposited on the surface. Hutton concluded his paper with his now- famous and for him unusually succinct statement The result therefore of our present enquiry is that we find no vestige of a beginningno prospect of an end. Causes Now in Operation The first quarter of the nineteenth century was a turning point in the history of geology. It was then that factsas opposed to scripture became the basis of geological theory. Although many scientiststheologians tried to reconcile the new geology with biblical accounts it became increasingly clear Earth was not only much older than anyone previously thought but older than anyone had ever imagined not thousands of years old but millions. Hutton laid the foundations of modern geology and set the stage for Charles Lyell who codified the idea of uniformitarianism in his three-volume work Principles of Geology 1830-1833. The subtitle said it all An attempt to explain the former changes of the Earths surface by reference to causes now in operation. Principles had a profound effect on mid- nineteenth century science. It popularized the idea of slow but steady change what we would now call gradualism and convinced most geologists Earth was very old. 3 unconformity at Jedburgh. In his book Theory of the Earth James Hutton wrote I rejoiced at my good fortune in stumbling upon an object so interesting in the natural history of the earth and which I had been long looking for in vain. First Dinosaurs As geologists were pushing back Earhts age paleontologists were making their own startling discoveries. In 1822 Gideon Mantell a doctor in Sussex found fossil teeth that looked like those of an iguanabut if scaled to size the animal would have been over thirty feet long. In 1824 the geologist William Buckland announced the discovery of giant bones in Oxfordshire that clearly did not belong to any living animal. Jaw of the Megalosaurus from William Bucklands monograph. Obviously these animals no longer existed and their fossils forced scientists to wrestle with the concept of extinction an idea that did not fit with traditional histories of life on Earth. Why would God create species only to have them disappear Name of the Beast The term dinosaur is from the Greek fearfully great lizard. It was first coined by Richard Owen in a scientific paper published in 1842. The Greek is often translated into the more sinister- sounding terrible making terrible lizard. Owen came up with the name to describe the giant reptiles discovered by Buckland and Mantell Megalosaurus Iguanodon and Hylaeosaurus. They were reptilian in many ways but they had unique featuresand they were far bigger than any living reptile. The biggest Megalosaurus great lizard was described by William Buckland in the 4 first scientific paper about a dinosaur ever published Notice on the Megalosaurus or great Fossil Lizard of Stonesfield in the Transactions of the Geological Society 1824. It is possible a Megalosaurus bone was featured in an earlier work The Natural History of Oxfordshire by Robert Plot 1677. Plot had been sent bones found in the area and included a drawing in his book of what appeared to be the end of a very large femur. Not having any scientific context for the fossil he presumed it was from a giant human. The actual bone has been lost. Megalosaurus was also the first dinosaur to appear in a work of fiction. In the first paragraph of Charles Dickenss Bleak House 185253 we find Implacable November weather. As much mud in the streets as if the waters had but newly retired from the face of the earth and it would not be wonderful to meet a Megalosaurus forty feet long or so waddling like an elephantine lizard up Holborn Hill. From their first discovery dinosaurs fascinated layman and scientist alike. Terrifying and mysterious they once ruled the world but then vanished. What did it mean Nineteenth century depiction of Megalosaurus. Early reconstructions were not accurate. Today we know that many dinosaurs-including Megalosaurus-were bipedal. 5 Mary Annning While Buckland and Mantell were discovering the fossils of giant land reptiles a young woman named Mary Anning was finding fossils of prehistoric marine reptiles. Near Lyme Regis on the south coast of England Mary and her family gathered shells and fossils and sold them to tourists to make extra moneythey were very poor. Mary was the inspiration for the rhyme She sells seashells on the seashore. But she did more than just collect seashells she discovered the first ichthyosaur and plesiosaur not technically dinosaurs but extinct prehistoric marine reptiles that lived at the same time-and which of course begged the same questions. She was well-known in paleontological circles and many famous scientists visited her including Buckland and Mantell. In the early nineteenth century dinosaurs and extinct marine reptiles played a key role in the development of evolutionary ideas because their discovery raised many questions and pointed scientists in new directions. If for example species could go extinct did that mean new species could come into existence And if so how Duria Antiquior A More Ancient Dorset. A scene by Henry de la Beche c1830 was based on the discoveries of Mary Anning. 6 A letter by Mary Anning 1823 describing her discovery of a plesiosaur. Anning not only collected fossils she was a recognized expert on them. 7 Charles Darwin question once he completed his work on barnacles in 1854. Even then Darwin might have taken years to publish had a package not arrived in 1858 from Alfred Russel Wallace enclosing a paper describing the same theory. Wallace was a self- taught naturalist who had spent years in the Amazon and the Spice Islands collecting rare and exotic insects and birds and like Darwin he was very observant. In 1855 Wallace published a paper entitled On the Law Which Has Regulated the Introduction of New Species in The Annals and Magazine of Natural History. First listing a number of facts regarding the geological history of Earth and the geographical distribution of animals he drew the following conclusion Every species has come into existence coincident both in space and time with a pre- existing closely allied species. Lyell read the article and saw that Wallace was on the same track as Darwin. He advised Darwin to publish but Darwin didnt think Wallace was a threat Wallaces Law didnt say anything about how new species came into existence and didnt want to publish until he amassed more evidence. Darwin wrote to Lyell in 1856 To give a fair sketch would be absolutely impossible for every proposition requires such an array of facts. Then in June 1858 the package arrived. Lyell and the botanist Joseph Dalton Hooker both friends of Darwin arranged for Wallaces paper to be published along with an extract from Darwins 1844 sketch and a letter from Darwin to Asa Gray dated 1857. Thus the first announcement of the theory of natural selection appeared as a joint Darwin-Wallace paper in the Journal of the Linnean Society August 1858. Jolted into action Darwin finished the Origin in little over a year. Charles Darwin Few names are as famous as Darwin. A Victorian naturalist from a well-to-do family he was at one point headed for the clergy. Through a serendipitous series of events however he ended up on a five-year voyage around the world. It changed his life. Born into the new geology Darwin looked at the world in a new way A world millions of years in the making and one still undergoing small imperceptible changes a dynamic stage upon which individual organisms act out fleeting existences. From the rain forests of South America to the Galpagos Islands Darwin saw firsthand the variation between individuals and the desperate fight for survival. He also saw the close relationship between species that lived nearby and similar relationships across time between fossil animals and their modern counterparts. Facts that made him doubt the fixity of species. When he read Thomas Malthuss book on population theory in 1838 he realized the cold logic of differential success could explain how populations changed over time as individuals competed for food sex and survival-all against the backdrop of an ever-changing landscape that slowly but continually altered the rules of the game. In 1842 Darwin wrote a brief overview of his theory and then expanded it into a longer sketch in 1844. Recognizing its importance he left instructions with his wife for its publication in the event of his death. Darwin then spent the next ten years working on his collections from the voyage publishing a number of important books and papers on his geological and zoological discoveries before finally returning to the species 9 The Mount Left A Municipal Map of Shrewsbury c1830. The Darwin house was called The Mount. 10 Early Years Charles Robert Darwin was born on February 12 1809 in Shrewsbury England. He grew up at The Mount the family home that overlooked the River Severn. His father Robert Waring Darwin 1766-1848 was a well-respected and successful physician. Darwins mother Susannah 1765-1817 died when he was eight years old and he was brought up by his older sisters who took charge of the household. From 1818 to 1825 he attended Shrewsbury School run by the Rev. Samuel Butler. In his autobiography Darwin wrote Nothing could have been worse for the development of my mind than Dr. Butlers school as it was strictly classical nothing else being taught except a little ancient geography and history. Darwin was more interested in the outdoors. At an early age he developed a passion for collectingshells minerals insectsand a love of fishing and hunting. But he was not a good student. At one point his father told him You care for nothing but shooting dogs and rat-catching and you will be a disgrace to yourself and all your family. In 1825 hoping he would make something of himself his father sent him off to Edinburgh to study medicine. Darwin however was not cut out to be a doctor. He attended two operations but he could not stay to see either finished preanesthesia operations were grisly affairs. In desperation his father sent him to Cambridge to prepare him for the clergy and it was there that he met John Stevens Henslow professor of Botany who would become his mentor. They talked so often Darwin became known as the man who walks with Henslow. Darwin later wrote No pursuit at Cambridge was followed with nearly so much eagerness or gave me so much pleasure as collecting beetles. It was the mere passion for collecting for I did not dissect them and rarely compared their external characters with published descriptions but got them named anyhow. I will give a proof of my zeal one day on tearing off some old bark I saw two rare beetles and seized one in each hand then I saw a third and new kind which I could not bear to lose so that I popped the one which I held in my right hand into my mouth. Alas it ejected some intensely acrid fluid which burnt my tongue so that I was forced to spit the beetle out which was lost as was the third one. But beetles were just the beginning. Soon after Cambridge he set out on a voyage that opened his eyes to the incredible diversity of life. As he himself said later The voyage of the Beagle has been by far the most important event in my life and has determined my whole career. Darwin aged six with his sister Catherine. 11 H.M.S. Beagle in the Galpagos Islands. Painting by John Chancellor. Robert FitzRoy captain of the Beagle. 12 The Voyage History is full of famous sea voyages from Columbuss journey to the new world to the first circumnavigation of Earth by Magellans ship Victoria. In modern atlases colorful dotted lines crisscross the worlds oceans marking the routes of Vasco da Gama and Sir Francis Drake Captain Cook and Jacques Cartier. Their adventures fill our history books and fire our imaginations with the thunder of cannons the horrors of scurvy and the discovery of new lands. Yet within this rich tapestry of triumph and disaster only a few voyages truly altered the course of history. The Beagle expedition is one. Circling the world from 1831 to 1836 the Beagle discovered no new continents fought no decisive sea battles nor returned laden with gold doubloons bolts of silk or exotic spices. But onboard was Charles Darwin. As the expeditions de facto naturalist he explored unknown reefs and volcanoes described new birds and reptiles and unearthed mysterious fossils and shells. He hacked his way through the rain forests of Brazil and clambered to the top of the Andes mountains. He experienced a devastating earthquake which shook the west coast of Chile and explored the tranquil coral islands of the Indian Ocean. From the Antarctic to the tropics Darwin studied the worlds geology plants and animals and as a result forged the most far-reaching theory in the history of science evolution by natural selection. Riding the Tide In 1831 the British Admiralty commissioned HMS Beagle under the command of Captain Robert FitzRoy to conduct surveys of the South American coast. The voyage presented a rare opportunity for a naturalist to accompany the expedition and Henslow recommended Darwin. Getting Darwin on board however was fraught with difficulties. First Darwins father objectedhe thought it a waste of time. At one point the position was offered to someone else. And as if there werent enough problems FitzRoy didnt like Darwins nose. As Darwin wrote in his autobiography He FitzRoy was an ardetn disciple of the physiognomist Johann Kaspar Lavater and was convinced that he could judge a mans character by the outline of his features and he doubted whether anyone with my nose could possess sufficient energy and determination for the voyage. But I think he was afterwards well satisfied that my nose had spoken falsely. The first week of September 1831 was tumultuous. Letters flew back and forth interviews were scheduled and canceled plans made and abandoned. Darwin overcame one obstacle only to face another but his destiny prevailed. On September 5 with the details of the voyage finally settled he wrote to his sister There is indeed a tide in the affairs of men I have experienced it. FitzRoy warned Darwin that space was tight but nothing prepared him for what he found at Devonport on September 13 a ten gun brig rebuilt as a three-masted bark a third mast the mizzen mast had been added before her first voyage ninety feet long with a beam of only twenty-four feet. The Beagle carried more than seventy men and in order to sleep at night Darwin had to remove a drawer to make room for his feet. Lack of space however was the least of his problems. Although the voyage was originally scheduled to leave in October there were many delays while the ship was refitted to FitzRoys 13 PlanofHMSBeagleaslatersketchedbycrewmemberPhilipGidleyKing. 14 exacting specifications. Twice the crew departed only to be driven back by gales. Finally on December 27 they set out for good on their five-year adventure. And the first thing Darwin learned was the agony of seasickness. He was ill almost the entire voyage scarcely able to get out of his hammock whenever the ship was at sea. He passed the tortuous hours reading the books he had brought along Alexander von Humboldts Personal Narrative Miltons Paradise Lost and a copy of the New Testament in Greek. Finding it impossible to even stand up without becoming seasick Darwin wondered if he made a serious mistake. The Beagles first stop was Tenerife in the Canary Islands but upon arrival the crew faced a quarantine of twelve days because England was in the middle of a cholera epidemic. FitzRoy did not hesitate. Up jib he ordered and to Darwins horror they sailed off immediately. Not only did Darwin want to visit the island he desperately wanted to stand on dry land. Fortunately the break he needed was not far off. On January 16 the Beagle reached Saint Jago in the Cape Verde Islands 300 miles off the African coast. Expecting it to be uninteresting Darwin found it electrifying. He saw for the first time the lush tropical flora he had read about in Humboldts Narrative an account of his visit to South America at the turn of the nineteenth century. It was everything Darwin had dreamed of a tangle of Tamarinds bananas palms a riot of bright colors and strange flowers in striking contrast to the islands black volcanic rocks. To his father he wrote It is utterly useless to say anything about the Scenery-it would be as profitable to explain to a blind man colours as to a person who has not been out of Europe the total dissimilarity of a Tropical view. Law of the Jungle On February 16 1832 they crossed the equator and on February 28 sailed into All Saints Bay at Baha Salvador where Darwin 15 took his first steps in South America. For the next year the Beagle made its way down the coast conducting surveys taking depth soundings and drawing charts while Darwin collected insects seashells and rocks. He did not put the pieces together until he returned to England but it was therein the heart of South Americathat Darwin made his first important discoveries. Lost in the brilliance of Brazils rain forest surrounded by parrots butterflies and orchids Darwin saw not only the incredible luxuriance and diversity of the Amazon but also the harsh reality of life within it. He watched a predatory wasp hunt down kill and drag off a spidera fight to the death between two tiny monsters a stark example of natures first law kill or be killed. Everywhere he looked was a ruthless struggle for survival vampire bats attacked horses in the dead of night an unstoppable column of army ants triggered panic throughout the forest. It was Darwins first real glimpse of the never-ending battle between the hunters and the hunted. In September at Baha Blanca south of Rio de Janeiro Darwin excavated several huge skeletons the remains of giant prehistoric beasts. One was a giant sloth similar to the present-day slothbut much biggerand there were also bones of a giant armadillo. Darwin marveled at their close resemblance to modern species. He would later write in his Journal This wonderful relationship in the same continent between the dead and the living will I have no doubt hereafter throw more light on the appearance of organic beings on our earth and their disappearance from it than any other class of facts. In October the ship returned to Montevideo where Darwin received the second volume of Charles Lyells Principles of Geology. Darwin had read volume one but volume two conveyed a more profound message. Lyell argued that Earth was much older than most people imagined and that the same geological processes observed in modern times had been at work for millions of years. He said the world had come about through causes now in operation not catastrophic events like the biblical flood. In fact by the 1830s all geologists accepted that the world was very ancient but no one could guess just how old. In his second volume Lyell argued that species became extinct because they no longer fit their environments as the world changed. Lyell was not an evolutionist but his observations must have made Darwin think If there was an explanation why species disappeared there must be one for how they came about in the first place. Mylodon robustus. From Richard Owens work on extinct sloths based partly on Darwins discoveries in South America. 16 Moving Mountains The Beagles crew spent the second year of the voyage 1833 surveying the east coast of South America while Darwin explored the interior on horseback. Eventually the ship made its way back to Tierra del Fuego where Darwin encountered another key piece of information. Earlier he had seen large rheas ostrich-like birds in the Pampas near Baha Blanca and had heard of a smaller and rarer rhea to the south it is now known unofficially as Darwins Rhea. Darwin was baffled by the presence of two similar kinds of birds in the same territory. While at Saint Gregorys Bay in the Straits of Magellan he met the giant Patagonians and questioned them about the tiny rhea. He learned it lived south of the Rio Negro while the larger one lived only north of the river. Thus Darwin acquired a small but important fact species appeared most similar to those in nearby but geographically separated areas rheas are flightless birds. After exploring the Santa Cruz River in April the Beagle rounded the Horn for the last time in May. Fighting through the dangerous channels lost in a world of rugged snowy crags blue glaciersand rainbows the Beagle made her way to the island of Chilo. After two weeks she headed north to Valparaiso Chile. From there Darwin struck out for the foothills of the Andes and reached Santiago on August 27. In September he fell seriously ill and barely got back to Valparaiso before collapsing for a month unable to get out of bed. Upon recovering the first news he heard was bad FitzRoy had suffered a nervous breakdown and had given up command of the Beagle. Ever the perfectionist the captain had pushed himself too far and snapped. Pringle Stokes the Beagles captain before FitzRoy shot himself at Port Famine in 1828 during the Beagles first voyage and FitzRoy appeared to be next. His officers however eventually convinced him to retake command and complete the journey. On November 21 the ship returned to Chilo. On an excursion across the island Darwin observed three volcanoes billowing smoke and on January 19 he saw Mount Osorno erupt. At midnight the sentry reported a fire on the horizon. At three in the morning Darwin and the rest of the crew stood on deck to watch the explosion of rock fire and lavaso bright it lit up the sky. Rhea darwinii. from the Zoology of the Beagle Volume 3 Birds John Gould. 17 British Admiralty Chart The Beagles route marked in red simplified. Darwin Landings Admiralty Chart No. 1375 Galpagos Islands. From surveys by Captain FitzRoy 1841. After circling the world for five years FitzRoys chronometrical measurements were off by only thirty- three seconds. The chronometer shown at right is Murray No. 803. Murray Nos. 542 and 584 sailed on the Beagle. The Benchuca bug facing page The Beagle then sailed north to Valdivia. On February 20 1835 Darwin once again experienced natures terrifying power. While exploring inland the ground shook as an earthquake struck the west coast. Two hundred miles north at Concepcion the cathedral was left in ruins and a twenty- foot tidal wave hit the city carrying a schooner into the center of town. Fires blazed everywhere. Amidst the wreckage however Darwin made another important discovery the beds of dead mussels were now above the high tide mark. The ground had risen several feet proof that Lyell was right. Indeed over millions of years the continents rise and fall creating and destroying mountains and reshaping the world in small imperceptible steps. As winter approached the ship again made its way north to Valparaiso and Darwin set out for the Andes with guides and mules. Making his way back to Santiago he pushed on through the mountains to Mendoza Argentina shivering through night frosts at 13000 feet and fighting against the thin air freezing winds and icy clouds. He spent one night in a small village just south of the city and remembered it well. He wrote in his Journal At night I experienced an attack for it deserves no less a name of the Benchuca a species of Reduvius the great black bug of the Pampas. It is most disgusting to feel soft wingless insects about an inch long crawling over ones body. Before sucking they are quite thin but afterwards become round and bloated with blood and in this state they are easily crushed. It is now known the Benchuca bug can transmit Chagas disease a debilitating potentially fatal disease that causes symptoms similar to many of those Darwin reported after he returned to England. His lifelong health problems may have started in Argentina. Turning northwest he crossed back through Uspallata Pass and stumbled across fossilized trees a petrified forest at the top of the world. The trees once must have stood on the coast when the ocean had come up to the foot of the mountains. Buried when the continent sank then thrust to the top when the continent rose up again the trees were tilted at impossible angles jutting out from the rock that had crumpled like paper. Darwin was slowly working out the puzzle. He fired off a letter to Henslow about his absurd and incredible discoveries. After Valparaiso the Beagle visited Iquique Peru then set off for a destination now forever linked with Darwins namethe Galpagos Islands. 19 Geospiza strenua one of the Galpagos finches. from The Zoology of the Beagle Volume 3 Birds John Gould. Darwin did not realize the significance of the finches until Gould categorized his specimens after he had returned home from the voyage. 20 Birds Tortoises Although the Beagle only stayed five weeks in the Galpagos it turned out to be an important stop for Darwin. The Galpagos Islands are a desolate volcanic archipelago ruled by giant tortoises and lizards. Six hundred miles off the coast of South America the landscape is bleak and prehistoric covered with black sand and lava the islands cut in half by the Equator. After visiting the islands in 1841 Herman Melville wrote The chief sound of life is a hiss. But for Darwin the Galpagos held important secrets. One of the first things he noticed was that a great number of Galpagos birds hawks mockingbirds water-sails herons were clearly related to birds in South America but with significant differences. As for the finches Darwin wrote in the first edition of his Journal 1839 It is very remarkable that a nearly perfect gradation of structure in this one group can be traced in the form of the beak from one exceeding in dimensions that of the largest gross-beak to another differing but little from that of a warbler. In the second edition 1845 he expanded on his observations The most curious fact is the perfect gradation in the size of the beaks in the different species of Geospiza finch from one as large as that of a hawfinch to that of a chaffinch and even to that of a warbler. The largest beak in the genus Geospiza is shown in Fig. 1 and the smallest in Fig. 3 but instead of there being only one intermediate species with a beak of the size shown in Fig. 2 there are no less than six species with insensibly graduated beaks...Seeing this gradation and diversity of structure in one small intimately related group of birds one might really fancy that from an original paucity of birds in this archipelago one species had been taken and modified for different ends. But that all came later. Darwin did not grasp their significance while in the Galpagos. It was only after the ornithologist John Gould sorted them out back in England and Darwin managed to retroactively figure out which islands they came from he had not labeled them properly that he realized their importance. He did however notice that each species of mockingbird was found only on one island and it was this fact-along with a statement by a local dignitary that he could at once tell from which island any tortoise was brought that first caused Darwin to think about how species varied between the islands and what that might mean. As a result while still on the Beagle Darwin began to doubt the immutability of species. In his notes about the how the birds mockingbirds not finches and tortoises of the Galpagos varied island to island he speculated If there is the slightest foundation for these remarks the Zoology of Archipelagos will be well worth examining for such facts would undermine the stability of species. Finches from the 2nd edition of Darwins Journal. 21 On the Reef From the Galpagos the Beagle crossed the Pacific visiting Tahiti on the way to New Zealand Australia and Tasmania. In Australia Darwin came across eucalyptus trees the kangaroo rat and the bizarre duck-billed platypus. The plants and animals he saw were much different from anything he had seen before. He later wrote An unbeliever in every thing beyond his own reason might exclaim Two distinct Creators have been at work. Ultimately Darwin would not need to invoke two Creators to explain the natural world indeed not even one. On March 14 1836 the Beagle departed from King Georges Sound Australia and headed north to the Keeling Cocos Islands. Here Darwin found giant clams brightly colored corals and emerald lagoons. At Keeling Darwin tested his new theory of coral reefs. He had theorized they were formed when mountains sank back into the sea the coral reefs that originally surrounded the islands were left as rings around a lagoon and he was right. Often thought of as only an evolutionary theorist Darwin was in fact an accomplished geologist botanist and zoologist. The ship did not stay long in this tropical paradise before setting out across its third great body of water the Indian Ocean. The Beagle arrived on Mauritius east of Madagascar on April 29. Captain John Lloyd the surveyor general happened to have an elephant on the island and Darwin rode it back to the ship when they left. From Mauritius they sailed to the Cape of Good Hope and from there to the Ascension Islands in the middle of the Atlantic Ocean. After almost five years the Beagle was almost home. When it set out on July 23 however it did not head north to England but west- southwest. Unbelievably FitzRoy returned to Baha in Brazil to double-check his measurements. Fortunately it would be the last detour. After five ocean crossings the Atlantic three times it was finally time to go home. The Beagle landed at Falmouth on October 2 1836 almost five years after it set out. Darwin had literally sailed around the world. He had spent 1 years at sea 3 years on land. Upon his return he wrote As far as I can judge of myself I worked to the utmost during the voyage from the mere pleasure of investigation and from my strong desire to add a few facts to the great mass of facts in natural science. As for his last objective we may safely say he succeeded. In 1842 Darwin published Coral Reefs. Although his solution was elegant and fit the facts he would not be proven right until the mid-twentieth century. 22 Return Home Development of the Theory Darwin set out in 1831 an aspiring naturalist headed for the clergy but he stepped off the Beagle in 1836 a different man. Before the voyage he had read William Paleys major works including A View of the Evidences of Christianity which was on the exams at Cambridge and Natural Theology. In his autobiography Darwin wrote The logic of this book Evidences and as I may add of his Natural Theology gave me as much delight as did Euclid. The careful study of these works without attempting to learn any part by rote was the only part of the academical course which as I then felt and as I still believe was of the least use to me in the education of my mind. I did not at that time trouble myself about Paleys premises and taking these on trust I was charmed and convinced by the long line of argumentation. In Natural Theology Paley invoked his famous watchmaker analogy any reasonable person upon finding a watch and seeing its complex and intricate design would assume it had been made by a watchmaker. In short design implies a designer. But by the time he returned Darwin was skeptical of such explanations. The question in Darwins mind was not do species evolve but how. Evolution itself was not a new idea. In 1809 Jean-Baptiste Lamarck had proposed that species changed by an underlying law of progress and the inheritance of acquired characteristics in his book Philosophie Zologique. Even Darwins own grandfather had written on the subject in Zoonomia 1794-1796 Erasmus Darwin had proposed that species adapt to their environment driven by lust hunger and danger an idea at least superficially similar to the theory of natural selection. But earlier theories were flawed or incomplete. Malthus and Population In September 1838 Darwin read An Essay on the Principle of Population by Thomas Malthus and a bell went off. Malthus argued that human population growth unless somehow checked would necessarily outstrip food production. Unchecked population growth according to Malthus would be exponential while the food supply could only grow arithmetically. Malthus was referring to human populations of coursehis objectives were socio-political not scientific. But Darwin quickly saw how the same principle could apply to the natural world. Far more offspring were born than could possibly survive because there simply wasnt enough food to go around. Individuals with a slight advantage would do better. Over a long period of time even the smallest advantage would prove decisive. Thanks to the new geology he had millions of years to work with. From the Brazilian rain forest to the Galpagos Islands Darwin had witnessed the considerable variation between individuals of the same species. He didnt know what caused such variations but he didnt need tohe theorized at a higher level. He contended that the struggle for existence acted upon the smallest differences however those differences came about. Forced to compete and to adapt to ever-changing environments which Darwin had also witnessed species evolved. In his autobiography Darwin wrote Here then I had at last got a theory by which to work. Marriage Family In 1839 Darwin married Emma Wedgwood his first cousin a practice not uncommon in Victorian England among the propertied 23 middle class. Although he had known Emma all his life she was one year older than he was and the two families were close it all happened rather quickly. He visited Maer Hall the Wedgwood family home upon his return from the voyage in late 1836 and made quite an impression on her. No longer the aimless young man who cared happy and proud of him it is delightful to see her. Emma did not see him much over the next few months because he had to rush around organizing collections manuscripts etc. but they met again at his brothers house in London in early 1837 and it confirmed her earlier impression. Darwin himself had begun only for shooting dogs and rat-catching he was now to be taken more seriouslya young man with stories about far-off places who spoke of new scientific discoveries. Emma wrote to her sister Fanny We enjoyed Charless visit uncommonlywe plied him with questions without any mercy. Harry and Frank made the most of him and enjoyed him thoroughly. Caroline Darwins sister looks so to think about marriage. To decide he made two columns headed Marry and Not Marry and wrote down pluses and minuses in each. If he married he noted he would have less money for booksand be forced to visit relatives. On the other hand he would have a constant companion friend in old age and the charms of music and female chit- chat though he worried about the loss of time. Emma and Charles Darwin. Wedding portraits c1839. 24 Erasmus 1731-1802 Josiah 1730-1795 John 1733-1803 Mary Howard 1740-1770 Elizabeth 1764-1846 Sarah 1734-1815 Elizabeth Hensleigh 1738-1790 Elizabeth 1847-1926 Mary 1842 William 1839-1914 Francis 1848-1925 Horace 1851-1928 Henrietta 1843-1929 7 others 12 others Anne 1841-1851 Robert 1766-1848 Charles 1809-1882 Leonard 1850-1943 Charles 1856-1858 George 1845-1912 Emma 1808-1896 Sussanah 1765-1817 Josiah II 1769-1843 Darwins Wedgwoods Allens M 1792 M 1764 M 1763 M 1737 M 1796 M 1839 4 others 5 others 4 others Darwin Family Tree Charles and Emma were First cousins sharing one set of Grandparents through Charless mother and Emmas Father. In the end he concluded he best get married. Emma was the obvious choice but when she saw him in London in 1838 she didnt think he was interested. Emma wrote to her Aunt Jessie The week I spent in London on my return from Paris I felt sure he did not care about me. It might have been nervesEmma was not only very pretty but quite accomplished she spoke French Italian and German played the piano brilliantly she had taken lessons from Frdric Chopin and was widely read. The Wedgwood family was also connected to many famous peopleone of Emmas aunts was a friend of Florence Nightingale an uncle was friends with Lord Byron Samuel Taylor Coleridge and William Wordsworth. To top it off Emma had already turned down several suitors. Darwin may have thought his chances slim. Nevertheless he summoned up his courage and proposed to her at Maer in November 1838. To his surprise she said yes. Over the next seventeen years they had ten children. Three died young Mary Eleanor at three weeks 1842 Charles Waring at age one 1856-1858 and Anne Elizabeth at age ten 1841-1851. Darwin was devastated when Annie died he was very close to her but the idea often put forward that her death influenced his work andor religious views does not fit the facts. Darwin completed the first sketch of his theory in 1842. In 1844 he expanded it to about 200 pages. Clearly Darwin had formulated his theory long 25 before Annie died. Nor did her death drive him away from God. Although he believed in Christianity when he was young by the late 1830s that was no longer true. In his autobiography he wrote Disbelief crept over me 1836 to 1839 at a very slow rate but was at last complete. We know his views had changed before he got married because Emma was concerned about them and said so in a number of letters she wrote him while they were still engaged. In November 1838 she wrote My reason tells me that honest conscientious doubts cannot be a sin but I feel it would be a painful void between us. I thank you from my heart for your openness with me I should dread the feeling that you were concealing your opinions from the fear of giving me pain. Darwin had leveled with her and although she had reservations and hoped he might yet come to a different conclusion she could find no fault in his goalthe search for truth. It was their mutual respecthe for her religious beliefs she for his scientific worldviewthat kept them together until the end. A Life of Poor Health In July 1842 Darwin moved the family which then included William and Annie from London to Down House. It was a secluded spot just outside the small village of Downe Kent about fifteen miles southeast of London. He would spend the rest of his life there. Darwin rarely left Down House because of ill health. He may have contracted Chagas disease in South America. The idea his illness was psychological connected to his work does not hold up under close examination because his health problems began on the voyage long before he started theorizing about evolution. He didnt record an encounter with the Benchuca bug on his first inland trip from Valparaiso to Santiago in South America it was on his second excursion he recorded the attack outside Mendoza but he was certainly exposed to the bug both times. The range of the Benchuca extends throughout the entire region and at the end of the first excursion he barely made it back to Valparaiso before collapsing for a month. Although not all his symptoms match those of Chagas disease many do including chronic fatigue nausea and abdominal pain. The cures of the day didnt help. At different times Darwin was prescribed or tried arsenic opium quinine morphine and even batteries the height of quackery which Darwin knew full wellthough he tried it anyway in desperationwhereby he galvanized his insides with electricity. The only thing that appeared to help was hydrotherapy a regimen of cold water strict diet and walks. He first tried the water cure at Malvern under Dr. James Gully and later at Moor Park under Dr. Edward Lane. It was likely the bland food and exercise that did him the most good not the water cure per se. Whatever the cause of his illness the effect was debilitating he could only work a few hours a day. It is remarkable what he managed to accomplish under such circumstances he wrote seventeen books made major contributions to numerous others and wrote dozens of important papers in geology botany and zoology. Often overlooked is the fact that had he not published the Origin he would still have been one of the leading scientists of his day highly respected in several fields. 26 Darwins handwriting was notoroiusly bad even he had trouble reading it. Shown here is a letter to the Rev. G. Smith about caves and bird beaks 1840. Darwins seal. His family motto was CAVE ET AUDE which translates as Beware and Dare. Darwin wrote thousands of letters. It was his main method of gathering information. he rarely left the house due to ill-health. 27 Delaying or Delayed One of the great myths surrounding the Origin is that Darwin delayed publishing the book for twenty years because he feared controversy. The facts however do not support this popular misconception. True Darwin had the critical insight in 1838 after reading Malthus and true he wrote out a sketch of the theory in 1842. Nevertheless Darwin had no intention of publishing anything until he had the facts to back it up. And before he could amass the facts he needed he had to finish the projects he had underway. Between 1838 and 1858 Darwin published his Journal from the voyage 1839 three volumes on the geology of the voyage 1842 1844 and 1846 and four volumes on barnacles two in 1851 two in 1854. He also edited the five-volume Zoology of the Beagle 1838-1843. R. B. Freemans bibliography of Darwins works lists sixteen major scientific papers between 1838 and 1858 and according to The Darwin Correspondence Project he wrote 1624 letters over the same period. He also got married moved twice and had ten children. He was not delaying he was delayed. The latest research has shown that the idea Darwin held back because he was afraid of what people might think is a modern invention. To the contrary Darwin was determined to publish regardless of what people thought. He had discussed his ideas with many peoplemost of whom disagreed with himand always made it clear that he intended to publish his theory despite their objections. Today it seems incredible that anyone would sit on a ground-breaking theory for twenty years but in mid-nineteenth century England the situation was much different. Darwin was in no hurry. Nor until Alfred Russel Wallaces letter arrived in 1858 did he think anyone else was on the same track. Not under any pressure the Darwin family was quite wealthy he was in no rush to publish. More to the point he knew the theory would not be accepted unless he could amass substantial evidence to support it and he was determined to do just that. By 1846 Darwin had wrapped up his geological work and had only the invertebrates left from the voyage. He decided to undertake the barnacles himself. But what he thought would be a yearlong project stretched into eight years because the whole group had to be described not just the specimens he had found and brought back himself. Near the end he would lament I hate a Barnacle as no man ever did before but he stuck it out and ultimately published two monographs so comprehensive they remain the definitive work on the subject. He finished the barnacles in 1854. Finally he could give his full attention to his theory. There is also evidence Darwin thought he needed to establish his credibility as a serious zoologist before claiming to have solved the mystery of mysteries as the astronomer John Herschel called the origin of species. In 1845 Hooker had written to Darwin criticizing the work of a French amateur named Grard saying I am not inclined to take much for granted from any one who treats the subject in his way who does not know what it is to be a specific Naturalist himself. There is no doubt this hit home because Darwin wrote back to Hooker the next day 28 How painfully to me true is your remark that no one has hardly a right to examine the question of species who has not minutely described many. Hooker did not mean it as a criticism of Darwin as he quickly explained in his next letter but the exchange took place just before Darwin started on the barnacles and he probably realized the truth in Hookers words whether or not they were meant for him. Darwin was not hesitant he was busy. He did not delay twenty years he was working. Only when he wrapped up the work from the voyageand established himself as an expert on an entire taxonomic groupdid he then return to the species question. Not long after he did a letter arrived that turned his world upside down. Out of the Blue Darwin was still a long way away from publishing his big species book when a package arrived on June 18 1858 from Alfred Russel Wallace a naturalist working in the Malay Archipelago modern-day Malaysia Indonesia and the Philippines. Wallace spent five years collecting in the Amazon before ending up in the Moluccas or Spice Islands and he too had read Malthus. As a result of his own observations he had reached the same conclusions as Darwin on the origin of species. In early 1858 half-crazed in the grip of malaria Wallace wrote a twenty-odd- page paper entitled On the Tendency of Varieties to Depart Indefinitely from the Original Type and posted it to Darwin for his opinion. When Darwin read it he was stunned. Although there were important differences Darwin wrote to Lyell If Wallace had my MS sketch written in 1842 he could not have written a better abstract. Darwin did not know what to do but Lyell and Hooker took charge and arranged for Wallaces paper to be presented along with an extract of Darwins 1844 essay and part Darwins monograph on living barnacles. 29 Darwin was stunned when he received a letter from A. R. Wallace describing the theory of natural selection but others had come up with similar theories before. When Darwin published the Origin in 1859 a man named Patrick Matthew wrote a letter to the Gardeners Chronicle claiming he had come up the principle of natural selection before Darwin. And indeed he had. Matthew was a Scottish landowner and fruit farmer and had published On Naval Timber and Aboriculture in 1831. It was a book about cultivating trees for shipbuilding. In an appendix to the work Matthew clearly describes the basic principles of natural selection. Darwin immediately wrote to the Gardeners Chronicle himself recognizing Matthews claim I freely acknowledge that Mr. Matthew has anticipated by many years the explanation which I have offered of the origin of species under the name of natural selection. I think that no one will feel surprised that neither I nor apparently any other naturalist had heard of Mr. Matthews views considering how briefly they are given and that they appeared in the appendix to a work on Naval Timber and Arboriculture. I can do no more than offer my apologies to Mr. Matthew for my entire ignorance of his publication. If another edition of my work is called for I will insert a notice to the foregoing effect. Which he did. But Matthew too had been anticipated. In 1818 a work by William Charles Wells was published posthumously Wells died the year before entitled Two Essays One Upon Single Vision with Two Eyes the other On Dew. Incredibly Wells had also described natural selection in an appendix. Darwins grandfather Erasmus Darwin discussed the idea of evolution in several works-most famously in Zoonomia published in 1794but he did not describe the mechanism of natural selection. But another work appeared in 1794 that did by none other than James Who Came up With Natural Selection First 30 Hutton the founder of the new geology. In his book Investigation of the Principles of Knowledge he wrote ...if an organised body is not in the situation and circumstances best adapted to its sustenance and propagation then in conceiving an indefinite variety among the individuals of that species we must be assured that on the one hand those which depart most from the best adapted constitution will be the most liable to perish while on the other hand those organized bodies which most approach to the best constitution for the present circumstances will be best adapted to continue in preserving themselves and multiplying the individuals of their race. He did not believe that such selection could lead to new species only that it would perfect existing ones. Nevertheless he stated the theory clearly and described how it would impact populations. In 1794. Why does Darwin get all the credit Because he worked out the details. It is not enough to simply announce a hypothesis. Darwin spent years studying artificial selection how animal breeders create varieties gathering evidence and working out the many problems. Only then did he publish the Origin. It was the scope and depth of Darwins work that convinced the scientific community that evolution had taken place. James Hutton 1794 timeline William Wells 1818 Patrick Matthew 1831 Darwin Wallace 1858 1800 1825 1850 1875 31 Alfred Russel Wallace sent Darwin a paper in 1858 that laid out a theory very similar to Darwins. 32 of a letter Darwin had written to Asa Gray a botanist in the United States in 1857. All designed to establish Darwins priority. The joint paper was read at a meeting of the Linnean Society on July 1 1858 by Lyell and Hooker Wallace was still in the Far East and Darwin was at his sons funeral. It was published later that year in the journal of the society. Two short reviews appeared in the Zoologist along with a reprint of the paper but it went largely unnoticed. It was not until the theory came out in book form that it made headlines. In fact in May 1859 Thomas Bell in his presidential report to the Linnean Society said The year which has passed 1858 has not indeed been marked by any of those striking discoveries which at once revolutionize so to speak the department of science on which they bear. This was almost certainly a deliberate slight. Bell had chaired the July meeting where the Darwin-Wallace paper was read and he knew Darwin well-he had written up Darwins reptiles from the voyage. Not a supporter of Darwins theory he unwittingly played a key role in its development it was Bell who confirmed the giant tortoises were native to the Galpagos Islands and not brought to the islands by buccaneers as Darwin originally thought making them a perfect example of natural selection by virtue of their island-to-island variation. On the Origin of Species On the Origin of Species by Means of Natural Selection was published on November 24 1859. The records of John Murray the publisher indicate 1250 copies were printed and that it sold out the first day to the booksellers. Natural Selection Darwin of course did not discover evolution. The idea that species evolved had been around for some time. The problem was that no one had offered a convincing explanation of how they evolved. Until Darwin. He called it natural selection. Considering its incredible explanatory power the theory of natural selection is remarkably simple. Limited resources there isnt enough food for all the offspring produced leads to competition. Some individuals will do better than others because they happen to have certain characteristics that give them an edge speed strength etc. Because those individuals are more likely to survive they are more likely to reproduce and pass on their characteristics to their offspring. Thus the population of a species evolves as more and more individuals are born and survive who have inherited the characteristics that provide advantage. When T.H. Huxley first read the Origin he said How extremely stupid not to have thought of that. A simple idea but a challenge to accepted wisdom and faith. It was critical but positive. Darwin liked the review and wrote to Gray Your Review seems to me admirable by far the best which I have read. I thank you from my heart both for myself but far more for subject-sake. Like Huxley in England Asa Gray became Darwins main supporter in the United States and just as Huxley sparred with Darwins opponents in England Gray squared off against Louis Agassiz at home both Gray and Agassiz were professors at Harvard University. Not uncritical of Darwins theory Grays main goal was to get it a fair hearing. The Origin was widely reviewed when it first appeared. Contrary to popular belief it received many positive reviews. 34 Early reviews The first review appeared in the Athenum on November 19 1859. It was written by John Leifchild. It was negative but not scathing. Next came T. H. Huxleys review in The Times which was positive. There followed reviews in numerous periodicals and newspapers some positive Hooker in the Gardeners Chronicle some negative Bishop Wilberforce in the Quarterly Review. The first American review was written by Asa Gray and it appeared in the March 1860 issue of the American Journal of Science and Arts. 35 thrash Wilberforce in the debate. But thats not what happened. Contemporary accounts though few and far between indicate Wilberforce did indeed conclude his speech with a comment about apes and ancestors although the exact words were not recorded. Huxley however did not say he would rather be descended from an ape than a bishop. In a letter to Frederick Dyster in September Huxley gave this account If then said I the question is put to me would I rather have a miserable ape for a grandfather or a man highly endowed by nature and possessed of great means and influence and Much Ado About Nothing One famous Darwin myth concerns the debate between Samuel Wilberforce Bishop of Oxford and T. H. Huxley Darwins Bulldog. The confrontation took place on Saturday June 30 1860 at Oxford University at the annual meeting of the British Association for the Advancement of Science. Legend has it Wilberforce ended his critique of Darwins theory by asking Huxley Are you descended from the apes on your grandfathers or grandmothers side Supposedly Huxley replied I would rather be descended from an ape than a Bishop and then proceeded to Caricatures of Bishop Wilberforce and T. H. Huxley appeared in Vanity Fair. yet who employs these faculties and that influence for the mere purpose of introducing ridicule into a grave scientific discussionI unhesitatingly affirm my preference for the ape. But the battle was not won right there on the spot as is often reported. In fact both sides claimed victory so it could not have been a totally one-sided affair. A Matter of Chance Beyond its religious implications many scientists and non-scientists alike could not bring themselves to accept Darwins theory because it seemed to lack direction or purpose. Not only did it eliminate mans special position in the natural order of things it made his very existence a function of chance. In late 1859 Darwin wrote to Lyell I have heard by round about channel that Herschel says my Book is the law of higgledy- piggledy. This shows a limited understanding of what Darwin said and how we understand evolution today. While it is true evolution is undirected and the source of variation is random the mechanism of natural selection is anything but. It may be relentless and blindbut it is not without purpose It favors variations that increase reproductive success. It acts to increase fitness. Although Darwin did not ignore his critics he didnt put too much stock in them either. In 1859 he wrote to John Lubbock I should be grateful for any criticism. I care not for Reviews but for the opinion of men like you Hooker Huxley Lyell c. There were problems with his theory he knew but none he thought insoluble. One problem however did concern him. It was pointed out by Fleeming Jenkin in an 1867 review. Jenkin was an engineer. He listed a number of objections to Darwins theory age of the Earth limits on variability etc. but the most problematical was Jenkins assertion that any favorable characteristic that emerged in any one individual would quickly be drowned out a result of breeding with the larger population. Novelty could not be sustained. There was no good answer to this problem at the time though we now know that characteristics are not blended but inherited in a more digital fashion through genes and therefore beneficial variations can be and are preserved. Nevertheless it was a serious problem at the time and one of the few that gave Darwin pause. Evolution of the Origin The Origin went through six editions during Darwins life and he made many small changes but in detail onlynone to the basic theory. One small change he later regretted. In the closing paragraph of the first edition Darwin wrote There is grandeur in this view of life with its several powers having been originally breathed by the Creator into a few forms or into one and that whilst this planet has gone cycling on according to the fixed law of gravity from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved. Darwin added by the Creator in the second edition 1860. In 1863 he wrote to Hooker I have long regretted that I truckled to public opinion used Pentateuchal term of creation by which I really meant appeared by some wholly unknown process. It is mere rubbish thinking at present of origin of life one might as well think of origin of matter. 36 In 1871 Darwin published The Descent of Man. He had deliberately avoided human evolution in the Origin but that hadnt workedthe whole controversy revolved around the obvious implication for humans and by the time the Descent was published the controversy was largely over. Nevertheless it was an important work because it also dealt with sexual selection. Darwin considered sexual selection a separate mechanism for explaining evolutionary change though it is now regarded as simply an aspect of natural selection. He explained sexual differences such as male antlers and the peacocks tail as the result of differential success in males either competing against other males or being chosen by females and therefore having more offspring. So much of Descent is on sexual selection it is effectively two distinct books. Darwin later explained During many years it has seemed to me highly probable that sexual selection has played an important part in differentiating the races of man When I came to apply this view to man I found it indispensable to treat the whole subject in full detail. Consequently the second part of the present work treating of sexual selection has extended to an inordinate length compared with the first part but this could not be avoided. Later Life Darwin did more than make small edits and corrections to the Origin in his later years. Yet to come were several major works. In 1862 he published On the Various Contrivances by which British and Foreign Orchids are Fertilised by Insects known simply as Orchids. Darwin wrote to John Murray his publisher I think this little volume will do good to the Origin as it will show that I have worked hard at details. In Orchids Darwin applied the principles of natural selection to make a startling prediction. First he described a remarkable flower from Madagascar called Angaecum sesquipedale A whip-like nectary of astonishing length hangs down beneath the labellum. In several flowers sent to me by Mr. Bateman I found the nectaries eleven and half inches long with only the lower inch and a half filled with very sweet nectar. Then he added in Madagascar there must be moths with probosces capable of extension to a length of between ten and eleven inches No such moth was known and Darwin was ridiculed by some scientists for suggesting it existed. But he was proven right. The moth was found and described forty-one years later in 1903. It had a wingspan of 13 to 15cm and a proboscis 25cm long 10 inches. It was a new subspecies and it was named Xanthopan morgani praedictathe predicted moth. 37 Xanthopan morganii praedicta. The predicted moth. In 1872 came The Expressions of the Emotions in Man and Animals another important book in which Darwin showed that humans and animals expressed similar emotions in similar ways pointing to common descent in contrast to Charles Bell who claimed in his 1824 work Essays on The Anatomy and Philosophy of Expression that humans had special facial muscles to express uniquely human emotions. Expressions was also one of the first books to include photographs. It featured seven heliotype plates. Darwin wrote five more books between 1875 and 1881 working almost up to his death. Darwin on Religion Much has been written about the reception of Darwins theory in his lifetime and after less about what Darwin thought himself. Generally Darwin tended to think of science and religion as two separate and distinct areas of inquiry. In 1866 he wrote to Mary Boole the wife of John Boole the mathematician and she herself a mathematician I am grieved that my views should incidentally have caused trouble to your mind but I thank you for your judgment honour you for it that theology science should each run its own course that in the present case I am not responsible if their meeting point should still be far off. Separate and distinct but not unconnected. His scientific worldview took precedence. He wrote to N.A. Mengden in 1879 Science has nothing to do with Christ except in so far as the habit of scientific research makes a man cautious in admitting evidence. This was the crux of Darwins skepticismby the end of the voyage having seen so much evidence firsthand he could no longer accept anything on faith. In his autobiography he wrote The old argument of design in nature as given by Paley which formerly seemed to me as conclusive fails now that the law of natural selection has been discovered. We can no longer argue that for instance the beautiful hinge of a bivalve shell must have been made by an intelligent being like the hinge of a door by man. There seems to be no more design in the variability of organic beings and in the action of natural selection than in the course which the wind blows. Everything in nature is the result of fixed laws. But not believing in established religion himself did not lead him to speak out against itpartly because he didnt think doing so would make any difference and partly because he did not want to offend his wife. Darwin said as much when he wrote to Edward Aveling in 1880 I am a strong advocate for free thought on all subjects yet it appears to me whether rightly or wrongly that direct arguments against Christianity theism produce hardly any effect on the public freedom of thought is best promoted by the gradual illumination of mens minds which follows from the advance of science. It has therefore been always my object to avoid writing on religion I have confined myself to science. I may however have been unduly biased by the pain which it would give some members of my family if I aided in any way direct attacks on religion. Perhaps our deepest insight comes from a letter he wrote to John Fordyce in 1879 In my most extreme fluctuations I have never been an atheist in the sense of denying the existence of a God. He added I think that generally and more and more as I grow older but not always that an Agnostic would be a more correct description of my state of mind. 38 Death and Funeral Charles Robert Darwin died on April 19 1882 at Down House. He was 73 years old. He was buried at Westminster Abbey. The funeral took place on April 26 the pallbearers included Huxley Hooker and Wallace. Darwin was laid to rest next to Sir John Herschel a man who had inspired Darwin when he was young but who refused to accept the theory of natural selection. A man of great honesty and modesty Darwin remains a giant in the history of science. On the Origin of Species is one of the most important scientific books ever published ranking with Issac Newtons Philosophi Naturalis Principia Mathematica Mathematical Principles of Natural Philosophy 1687 and Nicolaus Copernicuss De Revolutionibus Orbium Coelestium On the Revolutions of the Heavenly Spheres 1543works that changed not only our understanding of the world around us but of our place within it. But Darwins legacy goes beyond the theory of natural selection. His story embodies the spirit of science itself a keen observer with a love for natural history he set out on a voyage of discovery with only an open mind and returned with the answer to one of lifes greatest mysteries. 39 Darwins grave in Westminster Abbey. sequences but with only four lettersthe four bases that pair up to connect the two phosphate sugar backbones of the double- helix adenine cytosine guanine and thymine. ACGT. Four letters that demonstrate the common origin of life on Earth. The Tree of Life Non-scientists have often observed that it is easier to see how natural selection can explain microevolution like resistance to antibiotics than to see how it could lead to the emergence of an entirely new species. One of the key concepts in evolution through natural selection is the idea of splitting where one species becomes two. How does that happen One way is through geographic isolation. The rheas in South America are a good example. When he was in Patagonia Darwin found two species of rhea one large one small with different ranges the larger north of the Rio Negro the smaller one south of the river. Originally there was only one rhea. When a small group became separated from the main population it evolved into a slightly different species. In all likelihood a small group got separated by the Rio Negro River which now forms a boundary between the two populations. The water level probably dropped during a dry spell allowing a small population to cross over. When the water level returned to normal the two populations found themselves isolated rheas are flightless birds. Because the environments are slightly different on the two sides of the river the populations slowly diverged and became different species. Perhaps the original large rheas got cut off south of the river and slowly decreased in size their beaks also changingadaptations to different food sources andor predators. Evolution Today Darwins theory of natural selection has withstood the ultimate testthe test of time. Today 150 years after he first formulated it it remains the unifying concept in the biological sciences. Advances in molecular biology population statistics paleontology and other fields have all confirmed the basic tenets of the theory. Scientists no longer debate whether or not evolution has occurred and is occurring but instead focus on the details of the process and try to unravel its complex history. In retrospect it is remarkable Darwin was able to formulate the theory of natural selection given how little he knew. With no understanding of how traits are passed on from one generation to the next genes and no explanation for variation through genetic mutation and the variation inherent in sexual reproduction through genetic recombination he looked at the world around him and figured it out with only a handful of clues the inevitable struggle for survival the logic of differential success and the evidence of an ever-changing environment. From there he put the pieces together without understanding the finer details. One hundred years later an important piece of information came to light. In 1953 Francis Crick and James Watson elucidated the now famous double-helix structure of DNA along with Maurice Wilkins they won the Nobel Prize in 1962. Here was the structure that explained how information could be replicated and passed on biochemically from generation to generation. Here was the mechanism through which variation could arise. Most importantly here was the common denominator of all living things. The language of life written in staggeringly long 41 Evolution does not imply fish evolved into birds but rather that there was a common ancestor to both fish and birds that gave rise through millions of small steps over hundreds of millions of years to many different species including the fish and birds we see today. In the tree on the right the last common ancestor to fish and birds is marked . At this point the tetrapod line split off from the fishes as evidenced by such fossils as Tiktaalik and this new line led eventually to all the major tetrapod groups amphibians reptiles including birds and mammals. It takes a long time for new groups to emerge but evolution has been at work for four billion years. To put this in perspective if you took only one step each day but kept walking for four billion years you would travel 829545454 miles more than four times to the sun and back. Evolution works the same way millions of small stepswith many stops and starts over enormous periods of time. T H E T R E E O F LIF E 42 Bacteria Algae Ferns NonfloweringSeedPlants FloweringSeedPlants Mosses Fungi Sponges Flatworms SegmentedWorms Spiders Mollusks Insects Last common ancestor of all primates. Humans Chimpanzees Gorillas Orangutans Gibbons Lemurs NewWorld Monkeys OldWorld Monkeys Last common ancestor of all living things. Crustaceans Starfish Fish Amphibians Turtles Lizards Dogs Rabbits Rats Primates Crocodiles Marsupials Elephants Horses Birds Snakes Cats Tikta a lik 43 Two rheas is a long way from the estimated 10 million species living today but it doesnt take many splits to get there. After only four splits there are sixteen species and it grows exponentially. It takes only 23 splits to create almost 10 million unique species 223 8388608. And species can diverge rapidly through splitting. In the diagram below the small rhea and large rhea are not very different after one split but how different are species X and Y after four splits How different would X and Y be on a tree with ten million species across the top Even if each difference were tiny there would be dramatic differences across the entire group. Small changes add up. In some cases the apparent evolutionary leap appears to be too big to explain through small incremental adaptations. One critical transition for example was from fish to tetrapods four-legged animals which led to land-based animals. But such dramatic leaps did not necessarily occur all at once-what appears to be one step can be the sum of several smaller steps. In 2004 researchers found a fossil in Northern Canada called Tiktaalik Inuit for big freshwater fish. It is clearly fish-like yet it had developed certain features that would have enabled it to push its head up out of shallow watera primitive wrist that would have allowed its fins to bear weightand shoulder blades that were not attached to its skull unlike other fish thereby allowing greater movement of the head. These adaptations may have helped Tiktaalik exploit new sources of food like insects found along the shore by pushing its head up and out of the water to snatch them. Later as these adaptations continued to evolve they may have enabled descendants to crawl onto land at first for short periods of time but eventually enabling a permanent transition to new land-based life forms that led to the evolution of the tetrapods. Thus even small adaptations-made for one reason-can result in significant evolutionary change by opening up new possibilities in completely unrelated ways. Although the fossil record is imperfect it does in fact support the theory of evolution and the principle of common descent. Through transitional forms like Tiktaalik and others it is possible to connect all living things through the Tree of Life. 44 Large rheaSmall rhea Large rhea X Y Modern Dinosaurs Although we think of dinosaurs as extinct they are in fact all around us birds are dinosaurs. The idea that birds and dinosaurs are closely related is not new. Indeed the dinosaur-bird controversy dates back to Darwin with the discovery of Archopteryx ancient wing in 1861. It was described by Richard Owen in the Philosophical Transactions of the Royal Society 1863. This was quite fortuitous because Darwins Origin had just been published and transitional forms were a topic of debate. Hugh Falconer wrote to Darwin in January 1863 You were never more missed...for there has been this grand Darwinian case of the Archopteryx...Had the Solenhofen quarries been commissionedby august command to turn out a strange being la Darwinit could not have executed the behest more handsomelythan in the Archopteryx. Archopteryx was a strange fossil indeed. It had feathers but it also had reptilian features like a long bony tail and unfused bones in the wrist and ankle. Archopteryx also had teeth but that was not known until the late 1870s when the Berlin specimen was discovered the first specimen had no head. Owen who was opposed to Darwins theory was quick to classify it strictly as a bird and downplay its transitional nature but to others it was further evidence of a close evolutionary link between the two groups. Compsognathus a small theropod dinosaur caught T. H. Huxleys attention. He thought it was very bird-like and wrote about it in a paper entitled On the Animals Which are Most Nearly Intermediate Between Birds and Reptiles Geological Magazine 1868. To Huxleys point a specimen now in the Jura Museum in Eichsttt was originally identified as Compsognathus. Only when it was reexamined later was it determined to be a birdan Archopteryx no less. Huxley would refer to Compsognathus again when making an even more daring proposition It is certain that Compsognathus must have walked on its hind legs. The question then naturally arises did the gigantic dinosaurs such as Iguanodon and Megalosaurus have the same mode of progression This seems at first sight hard to believe but there is considerable reason for thinking it may have been the case. And he was right. We now know that many dinosaurs were bipedal. In a later paper Further Evidence on the Affinity between the Dinosaurian Reptiles and Birds published in the Quarterly Journal of the Geological Society in 1870 Huxley compared the hip structure of an emu dinosaur and crocodile and concluded there was an unmistakable transition between reptiles and birds. The dinosaur-bird hypothesis fell out of favor in the early twentieth century because the theropod specimens known at the time did do not have collarbones which when fused together form the furcula or wishbone in birds. Thus scientists concluded that birds must have descended from an earlier predinosaurian ancestor. It turns out however that theropods not only have collarbones they are already fused into the signature wishbone. The early specimens were either incomplete or the furcula had been misidentified. With that problem out of the way the theory reemerged in the 1970s. 45 46 Archopteryx. Plate from owens monograph. Recent evidence has confirmed the bird- dinosaur connection. In China for example a number of dromosaurs small theropods have been found with feathers including Caudipteryx and Sinornithosaurus. Full Circle Today there is near-universal agreement among scientists that birds are descended from dinosaurs. How fitting that dinosaurs would not only trigger a rethinking of the history of life on Earth when first discovered but end up a key example of evolution. Darwin does not mention dinosaurs in the first or second editions of the Origin probably because they were so poorly understood at the time and the fossil record so incomplete. 47 Diagram by Huxley comparing the hip structure of an emu 3 dinosaur 2 and crocodile 1. In the crocodile far right the pubis bone is pointed down and frontwards. In the bird far left it is pointed straight backwards. In the dinosaur center it is an intermediate position pointing down and back. But they made it into the third edition 1861 It is most difficult always to remember that the increase of every living being is constantly being checked by unperceived hostile agencies and that these same unperceived agencies are amply sufficient to cause rarity and finally extinction. So little is this subject understood that I have heard surprise repeatedly expressed at such great monsters as the Mastodon and the more ancient Dinosaurians having become extinct as if mere bodily strength gave victory in the battle of life. The lesson is clear enough size and strength are no guarantee of success in the highly competitive ever-changing game of Life. Its more complicated than that. Its survival of the fittest. 1 2 3 Books Your Inner Fish A Journey into the 3.5-Billion-Year History of the Human Body Neil Shubin. Pantheon Books 2008. Written in Stone Evolution the Fossil Record and Our Place in Nature Brian Switek. Bellevue Literary Press 2010. Journal of Researches and On the Origin of Species Charles Darwin. Available in modern reprints. Glorified Dinosaurs The Origin and Early Evolution of Birds Luis Chiappe. Wiley-Liss 2007. The Man Who Found Time James Hutton and the Discovery of the Earths Antiquity Jack Repchek. Basic Books 2009. Evolution The First Four Billion Years Michael Ruse. Belknap Press Harvard University Press 2009. Galapagos The Islands That Changed the World Paul Stewart. Yale 2007. The Making of the Fittest DNA and the Ultimate Forensic Record of Evolution Sean Carroll. Norton 2007. In the Light of Evolution Essays from the Laboratory and Field Jonathan Losos. Roberts Company 2011. on the Web Darwins Letters darwinproject.ac.uk Darwins Life aboutdarwin.com Works of Charles Darwin darwin-online.org.uk Dinosaurs on the Discovery Channel dsc.discovery.comdinosaurs Darwin at the Smithsonian mnh.si.eduexhibitsdarwinindex.html Geology geology.com Evolution evolution.berkeley.edu Human Origins www.amnh.orgexhibitionspermanent- exhibitions Dinosaur-Bird Evolution science.nationalgeographic.comscience prehistoric-world.html Web Resources on Evolution nationalacademies.orgevolution Explore. discover. learn. Fossils The Key to the Past Richard Fortey Price 27.50 This thorough introduction to the world of paleontology has been completely revised and updated reflecting changes in the ways that fossils are viewed and interpreted. Using the fluid writing style that made Trilobite Eyewitness to Evolution such a success Dr. Fortey brings the study of fossils into the 21st century. Platypus The Extraordinary Story of How a Curious Creature Baffled the World Ann Moyal Price 21.95 Few of the monotremes admirers have seen one in the wild fewer still know the key roles platypuses have played in theories of evolution. . . . Moyala historian of science based in Canberra Australiasets out to tell us all this and more in a cleanly written tome combining scientific curiosities with narrative history. Publishers Weekly A Gap in Nature Tim Flannery and Peter Schouten Price 69.99 A haunting look at 103 extinct species. This book is as close as we will ever get to these irretrievable animals and it is highly recommended for all libraries. Nancy Bent Booklist. Galpagos Smithsonian Natural History Series John Kircher Price 19.95 The Galpagos Islands are a paradise for birders botanists geologists and snorkelers with many islands still devoid of human habitation. John Kircher a renowned ecologist and Galpagos ecotour guide presents a detailed natural history of this spectacular archipelago. He looks at the amazing diversity of life found here from flamingos to penguins and explains the fascinating geology of these remote islands. Books available at the ABC Museum of Natural History Darwin dinosaurs Designed and produced by embeddedEXHIBITIONS ABC Museum of Natural History