CHAPTER XV

SCIENCE AND TRAVEL—THE VOYAGE OF THE BEAGLE

Sir Charles Lyell, in his Principles of Geology, the first edition of which appeared in 1830-1833, says: "If it be true that delivery be the first, second, and third requisite in a popular orator, it is no less certain that travel is of first, second, and third importance to those who desire to originate just and comprehensive views concerning the structure of our globe." The value of travel to science in general might very well be illustrated by Lyell's own career, his study of the mountainous regions of France, his calculation of the recession of Niagara Falls and of the sedimentary deposits of the Mississippi, his observations of the coal formations of Nova Scotia, and of the composition of the Great Dismal Swamp of Virginia—suggestive of the organic origin of the carboniferous rocks.

Although it is not with Lyell that we have here principally to deal, it is not irrelevant to say that the main purpose of his work was to show that all past changes in the earth's crust are referable to causes now in operation. Differing from Hutton as to the part played in those changes by subterranean heat, Lyell agreed with his forerunner in ascribing geological transformations to "the slow agency of existing causes." He was, in fact, the leader of the uniformitarians and opposed those geologists who held that the contemporary state of the earth's crust was owing to a series of catastrophes, stupendous exhibitions of natural force to which recent history offered no parallel. Also enlightened as to the significance of organic remains in stratified rock, Lyell in 1830 felt the need of further knowledge in reference to the relation of the plants and animals represented in the fossils to the fauna and flora now existing.

It is to Lyell's disciple, Charles Darwin, however, that we turn for our main illustration of the value of travel for comprehensive scientific generalization. Born, like another great liberator, on February 12, 1809, Darwin was only twenty-two years old when he received appointment as naturalist on H.M.S. Beagle, about to sail from Devonport on a voyage around the world. The main purpose of the expedition, under command of the youthful Captain Fitzroy, three or four years older than Darwin, was to make a survey of certain coasts in South America and the Pacific Islands, and to carry a line of chronometrical measurements about the globe. Looking back in 1876 on this memorable expedition, the naturalist wrote, "The voyage of the Beagle has been by far the most important event in my life, and has determined my whole career." In spite of the years he had spent at school and college he regarded this experience as the first real training or education of his mind.

Darwin had studied medicine at Edinburgh, but found surgery distasteful. He moved to Cambridge, with the idea of becoming a clergyman of the Established Church. As a boy he had attended with his mother, daughter of Josiah Wedgwood, the Unitarian services. At Cambridge he graduated without distinction at the beginning of 1831. It should be said, however, that the traditional studies were particularly ill suited to his cast of mind, that he had not been idle, and had developed particular diligence in different branches of science, and above all as a collector.

He was six feet tall, fond of shooting and hunting, and able to ride seventy-five or eighty miles without tiring. He had shown himself at college fond of company, and a little extravagant. He was, though a sportsman, extremely humane; had a horror of inflicting pain, and such repugnance at the thought of slavery that he quarreled violently with Captain Fitzroy when the latter condoned the abomination. Darwin was not, however, of a turbulent disposition. Sir James Sulivan, who had accompanied the expedition as second lieutenant, said many years after: "I can confidently express my belief that during the five years in the Beagle, he was never known to be out of temper, or to say one unkind or hasty word of or to any one."

Darwin's father was remarkable for his powers of observation, while the grandfather, Erasmus Darwin, is well known for his tendency to speculation. Charles Darwin possessed both these mental characteristics in an eminent degree. One who has conversed with him reports that what impressed him most in meeting the great naturalist was his clear blue eyes, which seemed to possess almost telescopic vision, and that the really remarkable thing about Darwin was that he saw more than other people. At the same time it will scarcely be denied that his vision was as much marked by insight as by careful observation, that his reasoning was logical and singularly tenacious, and his imagination vivid. It was before this supreme seer that the panorama of terrestrial creation was displayed during a five years' voyage.

No one can read Darwin's Journal descriptive of the voyage of the Beagle and continue to entertain any doubts in reference to his æsthetic sense and poetic appreciation of the various moods of nature. Throughout the voyage the scenery was for him the most constant and highest source of enjoyment. His emotions responded to the glories of tropical vegetation in the Brazilian forests, and to the sublimity of Patagonian wastes and the forest-clad hills of Tierra del Fuego. "It is easy," writes the gifted adolescent, "to specify the individual objects of admiration in these grand scenes; but it is not possible to give an adequate idea of the higher feelings of wonder, astonishment, and devotion, which fill and elevate the mind." Similarly, on the heights of the Andes, listening to the stones borne seaward day and night by the mountain torrents, Darwin remarked: "The sound spoke eloquently to the geologist; the thousands and thousands of stones, which striking against each other, made the one dull uniform sound, were all hurrying in one direction. It was like thinking on time, where the minute that now glides past is irrecoverable. So was it with these stones, the ocean is their eternity, and each note of that wild music told of one more step towards their destiny."

When the Beagle left Devonport, December 27, 1831, the young naturalist was without any theory, and when the ship entered Falmouth harbor, October 2, 1836, though he felt the need of a theory in reference to the relations of the various species of plants and animals, he had not formulated one. It was not till 1859 that his famous work on the Origin of Species appeared. He went merely as a collector, and frequently in the course of the voyage felt a young man's misgivings as to whether his collections would be of value to his Cambridge professors and other mature scientists.

Professor Henslow, the botanist, through whom Darwin had been offered the opportunity to accompany the expedition, had presented his pupil with the first volume of Lyell's Principles of Geology. (Perhaps, after Lyell, the most potent influence on Darwin's mind at this time was that of Humboldt and other renowned travelers, whose works he read with avidity.) At the Cape Verde Islands he made some interesting observations of a white calcareous stratum which ran for miles along the coast at a height of about forty-five feet above the water. It rested on volcanic rocks and was itself covered with basalt, that is, lava which had crystallized under the sea. It was evident that subsequently to the formation of the basalt that portion of the coast containing the white stratum had been elevated. The shells in the stratum were recent, that is, corresponded to those still to be found on the neighboring coast. It occurred to Darwin that the voyage might afford material for a book on geology. Later in the voyage, having read portions of his Journal to Captain Fitzroy, Darwin was encouraged to believe that this also might prove worthy of publication.

Darwin's account of his adventures and manifold observations is so informal, so rich in detail, as not to admit of summary. His eye took in the most diverse phenomena, the color of the sea or of rivers, clouds of butterflies and of locusts, the cacique with his little boy clinging to the side of a horse in headlong flight, the great earthquake on the coast of Chile, the endless variety of plant and animal life, the superstition of savage and padre, the charms of Tahiti, the unconscious humor of his mountain guides for whom at an altitude of eleven thousand feet "the cursed pot (which was a new one) did not choose to boil potatoes"—all found response in Darwin's open mind; everything was grist to his mill. Any selection from the richness of the original is almost sure to show a tendency not obvious in the Journal. On the other hand, it is just such multiplicity of phenomena as the Journal mirrors that impels every orderly mind to seek for causes, for explanation. The human intellect cannot rest till law gives form to the wild chaos of fact.

No disciple of Lyell could fail to be convinced of the immeasurable lapse of time required for the formation of the earth's crust. For this principle Darwin found abundant evidence during the years spent in South America. On the heights of the Andes he found marine shell fossils at a height of fourteen thousand feet above sea-level. That such an elevation of submarine strata should be achieved by forces still at Nature's command might well test the faith of the most ardent disciple. Of how great those forces are Darwin received demonstration on the coast of Chile in 1835. Under date of February 12, he writes: "This day has been memorable in the annals of Valdivia for the most severe earthquake experienced by the oldest inhabitant.... A bad earthquake destroys our oldest associations; the earth, the very emblem of solidity, has moved beneath our feet like a thin crust over a fluid." He observed that the most remarkable effect of this earthquake was the permanent elevation of the land. Around the Bay of Concepcion it was raised two or three feet, while at the island of Santa Maria the elevation was much greater; "on one part Captain Fitzroy found beds of putrid mussel shells still adhering to the rocks, ten feet above high-water mark." On the same day the volcanoes of South America were active. The area from under which volcanic matter was actually erupted was 720 miles in one line and 400 in another at right angles to it. Great as is the force at work, ages are required to produce a range of mountains like the Cordilleras; moreover, progress is not uniform and subsidence may alternate with elevation. It was on the principle of the gradual subsidence (and elevation) of the bed of the Pacific Ocean that Darwin accounted for the formation of coral reefs. Nothing "is so unstable as the level of the crust of this earth."

Closely associated with the evidence of the immensity of the force of volcanic action and the infinitude of time elapsed, Darwin had testimony of the multitude of plant and animal species, some gigantic, others almost infinitely small, some living, others extinct. We know that his thought was greatly affected by his discovery in Uruguay and Patagonia of the fossil remains of extinct mammals, all the more so because they seemed to bear relationship to particular living species and at the same time to show likeness to other species. The Toxodon (bow-tooth), for example, was a gigantic rodent whose fossil remains were discovered in the same region where Darwin found living the capybara, a rodent as large as a pig; at the same time the extinct species showed in its structure certain affinities to the Edentata (sloths, ant-eaters, armadillos). Other fossils represented gigantic forms distinctly of the edentate order and comparable to the Cape ant-eater and the Great Armadillo (Dasypus gigas). Again, remains were found of a thick-skinned non-ruminant with certain structural likeness to the Camelidæ, to which the living species of South American ruminants, the guanacos, belong.

Why have certain species ceased to exist? As the individual sickens and dies, so certain species become rare and extinct. Darwin found in Northern Patagonia evidence of the Equus curvidens, an extinct species of native American horse. What had caused this species to die out? Imported horses were introduced at Buenos Ayres in 1537, and so flourished in the wild state that in 1580 they were found as far south as the Strait of Magellan. Darwin was well fitted by the comprehensiveness of his observations to deal with the various factors of extinction and survival. He studied the species in their natural setting, the habitat, and range, and habits, and food of the different varieties. Traveling for three years and a half north and south on the continent of South America, he noticed one species replacing another, perhaps closely allied, species. Of the carrion-feeding hawks the condor has an immense range, but shows a predilection for perpendicular cliffs. If an animal die on the plain the polyborus has prerogative of feeding first, and is followed by the turkey buzzard and the gallinazo. European horses and cattle running wild in the Falkland Islands are somewhat modified; the horse as a species degenerating, the cattle increasing in size and tending to form varieties of different color. The soil being soft the hoofs of the horse grow long and produce lameness. Again, on the mainland, the niata, a breed of cattle supposed to have originated among the Indians south of the Plata, are, on account of the projection of the lower jaw, unable to browse as effectually as other breeds. This renders them liable to destruction in times of drought. A similar variation in structure had characterized a species of extinct ruminant in India.

How disastrous a great drought might prove to the cattle of the Pampas is shown by the records of 1825 and of 1830. So little rain fell that there was a complete failure of vegetation. The loss of cattle in one province alone was estimated at one million. Of one particular herd of twenty thousand not a single one survived. Darwin had many other instances of nature's devastations. After the Beagle sailed from the Plata, December 6, 1833, vast numbers of butterflies were seen as far as the eye could range in bands of countless myriads. "Before sunset a strong breeze sprung up from the north, and this must have caused tens of thousands of the butterflies and other insects to perish." Two or three months before this he had ocular proof of the effect of a hailstorm, which in a very limited area killed twenty deer, fifteen ostriches, numbers of ducks, hawks, and partridges. In the war of extermination that was ever before the great naturalist's eye in South America, what is it that favors a species' survival or determines its extinction?

Not only is the struggle between the animals and inanimate nature, the plants and inanimate nature, plant and animal, rival animals, and rival plants; it goes on between man and his environment, and, very fiercely, between man and man. Darwin was moved by intense indignation at the slavery on the east coast and the cruel oppression of the laborer on the west coast. He was in close contact with the sanguinary political struggles of South America, and with a war of attempted extermination against the Indian. He refers to the shocking but "unquestionable fact, that [in the latter struggle] all the women who appear above twenty years old are massacred in cold blood! When I exclaimed that this appeared rather inhuman, he [the informant] answered, 'Why, what can be done? they breed so!'"

In all his travels nothing that Darwin beheld made a deeper impression on his sensitive mind than primitive man. "Of individual objects, perhaps nothing is more certain to create astonishment than the first sight in his native haunt of a barbarian—of man in his lowest and most savage state. One's mind hurries back over past centuries, and then asks, could our progenitors have been men like these?... I do not believe it is possible to describe or paint the difference between savage and civilized man." It was at Tierra del Fuego that he was particularly shocked. He admired the Tahitians; he pitied the natives of Tasmania, corralled like wild animals and forced to migrate; he thought the black aborigines of Australia had been underestimated and remarked with regret that their numbers were decreasing through their association with civilized man, the introduction of spirits, the increased difficulty of procuring food, and contact with European diseases. In this last cause tending to bring about extinction there was a mysterious element. In Chile his scientific acumen had been baffled in the attempt to explain the invasion of the strange and dreadful disease hydrophobia. In Australia the problem of the transmission to the natives of various diseases, even by Europeans in apparent health, confronted his intelligence. "The varieties of man seem to act on each other in the same way as different specimens of animals—the stronger always extirpating the weaker."

It was at Wollaston Island, near Cape Horn, however, that Darwin saw savage men held in extremity by the hard conditions of life, and at bay. They had neither food, nor shelter, nor clothing. They stood absolutely naked as the sleet fell on them and melted. At night, "naked and scarcely protected from the wind and rain of this tempestuous climate," they slept on the wet ground coiled up like animals. They subsisted on shell fish, putrid whale's blubber, or a few tasteless berries and fungi. At war, the different tribes are cannibals. Darwin writes, "It is certainly true, that when pressed in winter by hunger, they kill and devour their old women before they kill their dogs." A native boy, when asked by a traveler why they do this, had answered, "Doggies catch otters, old women no." In such hard conditions what are the characteristics that would determine the survival of individual or tribe? One might be tempted to lay almost exclusive emphasis on physical strength, but Darwin was too wise ultimately to answer thus the question that for six or seven years was forming in his accurate and discriminating mind.

On its way west in the Pacific the Beagle spent a month at the Galapagos Archipelago, which lies under the equator five or six hundred miles from the mainland. "Most of the organic productions are aboriginal creations, found nowhere else; there is even a difference between the inhabitants of the different islands; yet all show a marked relationship with those of America." Why should the plants and animals of the islands resemble those of the mainland, or the inhabitants of one island differ from those of a neighboring island? Darwin had always held that species were created immutable, and that it was impossible for one species to give rise to another.

In the Galapagos Archipelago he found only one species of terrestrial mammal, a new species of mouse, and that only on the most easterly island of the group. On the South American continent there were at least forty species of mice, those east of the Andes being distinct from those on the west coast. Of land-birds he obtained twenty-six kinds, twenty-five of which were to be found nowhere else. Among these, a hawk seemed in structure intermediate between the buzzard and polyborus, as though it had been modified and induced to take over the functions of the South American carrion-hawk. There were three species of mocking-thrush, two of them confined to one island each. There were thirteen species of finches, all peculiar to the archipelago. In the different species of geospiza there is a perfect gradation in the size of the beaks, only to be appreciated by seeing the specimens or their illustrations.

Few of the birds were of brilliant coloration. The same was true of the plants and insects. Darwin looked in vain for one brilliant flower. This was in marked contrast to the fauna and flora of the South American tropics. The coloration of the species suggested comparison with that of the plants and animals of Patagonia. Amid brilliant tropical plants brilliant plumage may afford means of concealment, as well as being a factor in the securing of mates.

Darwin found the reptiles the most striking feature of the zoölogy of the islands. They seem to take the place of the herbivorous mammalia. The huge tortoise (Testudo nigra) native in the archipelago is so heavy as to be lifted only by six or eight men. (The young naturalist frequently got on the back of a tortoise, but as it moved forward under his encouragement, he found it very difficult to keep his balance.) Different varieties, if not species, characterize the different islands. Of the other reptilia should be noted two species of lizard of a genus (Amblyrhynchus) confined to the Galapagos Islands. One, aquatic, a yard long, fifteen pounds in weight, with "limbs and strong claws admirably adapted for crawling over the rugged and fissured masses of lava," feeds on seaweed. When frightened it instinctively shuns the water, as though it feared especially its aquatic enemies. The terrestrial species is confined to the central part of the group; it is smaller than the aquatic species, and feeds on cactus, leaves of trees, and berries.

Fifteen new species of sea-fish were obtained, distributed in twelve genera. The archipelago, though not rich in insects, afforded several new genera, each island with its distinct kinds. The flora of the Galapagos Islands proved equally distinctive. More than half of the flowering plants are native, and the species of the different islands show wonderful differences. For example, of seventy-one species found on James Island thirty-eight are confined to the archipelago and thirty to this one island.

In October the Beagle sailed west to Tahiti, New Zealand, Australia, Keeling or Cocos Islands, Mauritius, St. Helena, Ascension; arrived at Bahia, Brazil, August 1, 1836; and finally proceeded from Brazil to England. Among his many observations, Darwin noted the peculiar animals of Australia, the kangaroo-rat, and "several of the famous Ornithorhynchus paradoxus," or duckbill. On the Keeling or Cocos Islands the chief vegetable production is the cocoanut. Here Darwin observed crabs of monstrous size, with a structure which enabled them to open the cocoanuts. They thus secured their food, and accumulated "surprising quantities of the picked fibres of the cocoanut husk, on which they rest as a bed."

In preparing his Journal for publication in the autumn of 1836 the young naturalist saw how many facts pointed to the common descent of species. He thought that by collecting all facts that bore on the variation of plants and animals, wild or domesticated, light might be thrown on the whole subject. "I worked on true Baconian principles, and, without any theory, collected facts on a wholesale scale." He saw that pigeon-fanciers and stock-breeders develop certain types by preserving those variations that have the desired characteristics. This is a process of artificial selection. How is selection made by Nature?

In 1838 he read Malthus' Essay on the Principle of Population, which showed how great and rapid, without checks like war and disease, the increase in number of the human race would be. He had seen something in his travels of rivalry for the means of subsistence. He now perceived "that under these circumstances favorable variations would tend to be preserved, and unfavorable ones to be destroyed. The results of this would be the formation of a new species." As special breeds are developed by artificial selection, so new species evolve by a process of natural selection. Those genera survive which give rise to species adapted to new conditions of existence.

In 1858, before Darwin had published his theory, he received from another great traveler, Alfred Russel Wallace, then at Ternate in the Moluccas, a manuscript essay, setting forth an almost identical view of the development of new species through the survival of the fittest in the struggle for existence.