Humboldt's Cosmos

by Gerard Helferich

  They had been advised not to make their climb after a day of fine weather, since at this time of year it was unlikely to find two clear days in a row. Now the wisdom of that advice was revealed. The weather was deteriorating, and slender streaks of vapor rose up the mountain in the morning breeze. Still ascending, the climbers became enveloped in mist so thick that they could barely find their way, even on their hands and knees. After four more hours of hard going, the grade moderated at a little wood called the Pejual, and, despite the bad weather and difficult terrain, Humboldt “felt an indescribable pleasure in examining the plants of this region. Nowhere, perhaps, can be found collected together, in so small a space, productions so beautiful, and so remarkable in regard to the geography of plants,” he wrote.

  In fact, on the Silla de Caracas, the very first of many mountains he would climb in the New World, Humboldt confirmed some of his ideas about plant distribution and made several observations that Charles Darwin would later marshal as evidence for the theory of natural selection. Here on the Silla, just as in the hills outside Cumaná, Humboldt was struck by the similarity between the local flora and plants he knew from Europe. The rhododendrons bore a striking resemblance to those he had seen in the Alps. In the valley below was a willow (later named Salix humboldtiana) comparable to ones growing at home. Other travelers had made similar findings: Grasses like those in Switzerland had been found in the Straits of Magellan; more than forty flowering plants known in Europe had also been discovered in Australia; a violet once thought unique to Tenerife had been seen in the Pyrenees. And so on.

  What could account for such similar plants growing half a world apart? Though soil and atmospheric pressure no doubt played a role, the key factor was temperature, Humboldt realized. Similar plants tended to grow where the average temperatures were comparable, which sometimes meant at corresponding latitudes—in Pennsylvania and central France, for instance. But average temperature wasn’t determined only by distance from the equator; height above sea level must also be factored in. How to keep track of all these variables of latitude and altitude and to organize the data in a way that would let the underlying patterns emerge? His solution was as elegant as it was functional—lines could be drawn on a map connecting those places with the same mean temperature. It would be along such lines that one would expect to find similar species of plants. Invented as a tool for discovering “the unity of nature,” Humboldt’s isotherms proved a cornerstone of climatology, allowing an immediate visual comparison of climate from region to region. The technique, still universal in meteorology, is also familiar to anyone who has ever watched the Weather Channel or checked the weather map in the daily newspaper.

  But climate only created the conditions for plants to grow. How did similar species actually arrive at these far-flung locales? How could the plants have traveled across the ocean? Humboldt, like Darwin after him, concluded that simple migration couldn’t account for the spread of species around the globe. Or even across a single continent. In South America, for instance, the Andes provided an impassable barrier, yet the same plants were found on either side. How could they have crossed some of the highest mountains in the world? (Today, we know that the geographical distribution of plants is determined by a complex interplay of geologic and climatic factors—the shifting of tectonic plates, the rise of mountains, the advance and retreat of glaciers—but at the beginning of the nineteenth century such concepts were still well in the future.)

  True, Humboldt allowed, all these widely distributed plants might not be exactly the same, but they were definitely related: “When nature does not present the same species, she loves to repeat the same genera.” Thus Humboldt, like Darwin, also noted differences in geographically isolated species. But whereas both Humboldt and Darwin asked why the plants were so similar, only Darwin went on to ask why they weren’t exactly the same. That is, how had the various species come to diverge? It was by framing the question the other way around that the Briton would remake the science of biology and revolutionize our understanding of man’s place in the natural world. Still, Humboldt’s obsessive cataloging would provide Darwin with important evidence for his theory. On the Origin of Species cites the variety of plants growing on the Silla de Caracas, as detailed in Humboldt’s Personal Narrative, as exactly the type of biological diversity that the theory of natural selection sought to explain.

  Engrossed in their botanizing, Humboldt and Bonpland lingered on the Silla, though the sky was growing blacker and the temperature had dropped to barely fifty degrees. Eventually they crossed the western, lower hump of the saddle and entered the hollow between the two peaks, where they hacked a path through a dense forest. The fog was now so thick that they could guide their way only by compass—so that at every step they were in danger of plummeting over the sheer, six-thousand-foot ledge into the sea below. Finally they were forced to stop and, while waiting for the weather to clear, were rejoined by some slaves sent up with provisions. Whether the Capuchin had miscalculated or whether the slaves had helped themselves along the way, all that arrived were some olives and a little bread. “Horace, in his retreat at Tibur, never boasted of a repast more light and frugal,” Humboldt commented dryly, “but olives, which might have afforded a satisfactory meal to a poet, devoted to study, and leading a sedentary life, appeared an aliment by no means sufficiently substantial for travelers climbing mountains.” And it had been nine hours since they’d come across a spring.

  Their duty done, the slaves were intent on leaving again, and Humboldt and Bonpland had a hard time stemming a mass desertion. Eventually they sent down half the servants, with orders to rejoin them in the morning with some salt beef. No sooner had they made these arrangements than a strong, warm wind began to blow from the east and, within two minutes, dissolved the mist and revealed the Silla’s peaks again. The party resumed the climb, leaving the forest and entering an area of grass and low shrubs leading to the summit. Their route led very close to the precipice, but with typical understatement, Humboldt reassured those who would seek to follow him: “This part of the way is not dangerous, provided the traveler carefully examines the stability of each rock fragment on which he places his foot.”

  After another forty-five minutes, the party reached the summit, about eight thousand feet above sea level. The view was spectacular, encompassing the ocean, the Valley of Caracas, even the Ocumare Mountains, beyond which were hidden the Orinoco and the mighty Amazon. But the climbers didn’t have long to enjoy the vista before a milky-white fog rolled up from the valley, partially obscuring the sun. Humboldt rushed to make as many measurements as he could—with sextant, dip needle, barometer, thermometer, cyanometer—but was harassed by small, hairy bees clinging to his hands and face. The guides assured him that the bees wouldn’t sting unless grasped by their legs, but, for once, Humboldt wasn’t tempted to try the experiment.

  With the fog thickening, the party inched down the mountain, gathering a previously unknown genus of grass along the way. Back in the hollow between the peaks, Humboldt was surprised to discover quartz pebbles that had been rounded by running water. Clearly the Silla had once been submerged. His mentor, Werner, would have explained that the primordial seas had reached this high before subsiding, but Humboldt found it hard to believe that the earth had ever been covered in water so deep. More likely, he thought, the peaks of the Silla and all the mountains along the coast had been heaved up by volcanic forces. The more he saw of South American geology, the further Humboldt seemed to be moving toward the vulcanist camp.

  By now it was four-thirty in the afternoon. The party retraced their steps to the enchanting Pejual, where they collected yet more specimens. “When, in these climates,” Humboldt confesses, “a botanist gathers plants to form his herbal, he becomes difficult in his choice in proportion to the luxuriance of the vegetation. He casts away those which have been first cut, because they appear less beautiful than those which were out of reach. Though loaded with plants before quitting the Pejual, we still
regretted not having made a more ample harvest.” In fact, Humboldt and Bonpland were so bewitched by the botanical abundance that they lost track of the hours. By the time they reached the savannah below, the fleeting tropical twilight had passed, leaving them in absolute darkness still at an altitude of five thousand feet and buffeted by a rough, cold wind. The moon drifted in and out of clouds, and the resulting play of light and shadow created the illusion of precipices in the grass. Pulling off their boots for better traction, the climbers had to make their way on all fours to keep from slipping in the slick vegetation. One by one the guides deserted them to sleep on the mountain, but among those who remained was a slave from the Congo, who effortlessly balanced the large dip needle on his head, seemingly oblivious to the difficult terrain.

  As they descended, the mist gradually dissipated, and lights from the valley came into view. Voices and even guitar music wafted up to them. Yet the longer they walked, the farther the valley seemed to recede. Toward the end, the remaining guides lost their way trying to find a shortcut to the farm where the party was to spend the night, and the resulting detour presented the steepest descent of all. It was ten o’clock when they finally reached the floor of the valley, after an arduous six-hour climb down. The Europeans’ feet were bloody from the rocks and dry grass stalks, and everyone in the party was consumed by hunger and thirst, having hiked for fifteen hours with scant food or water. One can imagine how deeply Humboldt and Bonpland must have slept that night, not just from exhaustion but also from satisfaction at all those botanical specimens in their collecting cases, waiting to be dried, classified, and, someday, exhibited to their colleagues in science.

  THE weather had changed. It was time to push into the Amazon. On the evening of February 7, Humboldt and Bonpland left Caracas for the Llanos, the great savannahs extending between the coast and the rain forest. A dozen years later, the city that Humboldt knew ceased to exist. Caracas had suffered several previous earthquakes, including one just two years after Humboldt’s visit, but none was as violent as the one of March 26, 1812, during Venezuela’s war of independence. Beginning the year before, the area around Caracas experienced unusually violent tremors. In fact—counter to Werner’s theory that local causes, such as burning subterranean coal, were responsible for volcanic activity—the years 1811 to 1813 were particularly active, geologically speaking, throughout a wide region of the Western Hemisphere, with new islands created in the West Indies and earthquakes as far away as Tennessee and Kentucky.

  March 26, 1812, the day of the Caracas quake, was clear and unusually warm. As it was Ascension Thursday on the Christian calendar, most of the residents were in church when the first shock struck, at seven minutes after four in the afternoon. Though the tremor lasted just five or six seconds, it was powerful enough to ring church bells throughout the city. The townspeople thought the danger had passed, when a tremendous subterranean roar was heard, resembling a peal of thunder but longer and louder. The second shock, measured between fifty and seventy-two seconds in duration, leveled the city and buried nine to ten thousand people in the rubble. The churches of La Trinidad and Alta Gracia, a hundred fifty feet tall and supported by pillars twelve to fifteen feet in diameter, were reduced to a heap of rubble scarcely six feet high. The military barracks were swallowed by the earth, taking their occupants with them. Ninety percent of the city was demolished, and much of what remained was uninhabitable.

  “The night of the Festival of the Ascension witnessed an awful scene of desolation and distress,” Humboldt would later write, drawing on contemporary accounts.

  The thick cloud of dust which, rising above the ruins, darkened the sky like a fog, had settled on the ground. No commotion was felt, and never was a night more calm or more serene. The moon, then nearly at the full, illumined the rounded domes of the Silla, and the aspect of the sky formed a perfect contrast to that of the earth, which was covered with the bodies of the dead, and heaped with ruins. Mothers were seen bearing in their arms their children, whom they hoped to recall to life. Desolate families were wandering through the city, seeking a brother, a husband, or a friend, of whose fate they were ignorant, and whom they believed to be lost in the crowd. The people pressed along the streets, which could be traced only by the long line of ruins. . . .

  Wounded persons, buried beneath the ruins, were heard imploring by their cries the help of the passers-by, and nearly two thousand were dug out. Never was pity more tenderly evinced; nor was it more ingeniously active than in the efforts employed to save the miserable victims whose groans reached the ear. Implements for digging and clearing away the ruins were entirely wanting; and the people were obliged to use their bare hands, to disinter the living. . . . Beds, linens to dress the wounds, instruments of surgery, medicines, every object of the most urgent necessity, was buried in the ruins. Everything, even food, was wanting; and for the space of several days water became scarce in the interior of the city. . . .

  There was a duty to be fulfilled to the dead, enjoined at once by piety and the dread of infection. It being impossible to inter so many thousand bodies, half-buried under the ruins, commissioners were appointed to burn them: and for this purpose funeral pyres were erected between the heaps of ruins. . . . Amidst so many public calamities, the people devoted themselves to those religious duties which they thought best fitted to appease the wrath of heaven. Some, assembling in processions, sang funeral hymns; others, in a state of distraction, made their confessions aloud in the streets. . . . Children found parents, by whom they had never till then been acknowledged; restitutions were promised by persons who had never been accused of fraud; and families who had long been at enmity were drawn together by the tie of common calamity.

  Five: The Llanos

  LLANOS translates from the Spanish as “plains,” but the word fails to capture the rugged essence of the land. Formed over millions of years by the erosion of the Andes, South America’s steppes are forbidding, unsuited to raising crops, sparsely inhabited. Yet these bleak grasslands extend southward from Venezuela’s coastal mountains, and to journey from Caracas to the great rain forest beyond, Humboldt had no alternative but to trek across this rugged territory. In fact, he found the stark landscape, so different from the lush coast, one of the truly awe-inspiring experiences of his five-year odyssey (which took in some of the planet’s geographical superlatives): “I know not,” he wrote, “whether the first aspect of the Llanos excite[s] less astonishment than that of the chain of the Andes.”

  The Llanos’ size alone is daunting. Sprawling from the mountains of Caracas to the forests of Guiana to the delta of the Orinoco, the savannahs occupy some 225,000 square miles—an area larger than France. But to Humboldt, raised in mountainous, populous Germany, the desolation and absolute flatness were even more unsettling. “There is something awful, as well as sad and gloomy, in the uniform aspect of these steppes,” he found. “Neither hill nor cliff rises, like an island in the ocean, to break the uniformity of the boundless plain. . . . Like the ocean, the Steppe fills the mind with the feeling of infinity. . . . Yet the aspect of the clear, transparent mirror of the ocean, with its light, curling, gently foaming, sportive waves, cheers the heart like that of a friend; but the Steppe lies stretched before us dead and rigid, like the stony crust of a desolated planet. . . .” Moreover, here “no Oasis recalls the memory of earlier inhabitants; no carved stone, no ruined building, no fruit tree . . . speaks of the art of industry of former generations. As if estranged from the destinies of mankind and riveting attention solely to the present moment, this corner of the earth appears as wild theater for the free development of animal and vegetable life. . . .”

  In May, as the Llanos’ rainy season begins, the grasses put out tender green shoots, mimosas and aquatic plants blossom, and boas and crocodiles emerge from the mud where they’ve been estivating. Then, as the downpours continue, water collects in muddy, malarial sloughs, and the myriad rivers, all tributaries of the Orinoco, begin to swell. Huge tracts of the Llanos f
lood, forming an inland sea navigable by oceangoing ships. The fauna—native species such as jaguars, agoutis (nocturnal rodents about the size of a rabbit), deer, antelope, armadillos, hares, capybaras (the largest of the rodents, growing up to four feet long), as well as domesticated animals such as horses, cattle, oxen, and mules—are forced to swim from island to island in search of pasturage or prey, struggling to avoid the crocodiles and electric eels en route.

  But Humboldt crossed the Llanos in March, toward the end of the dry season, when the plains exude a menacing, unearthly sterility. “Everything seems motionless,” he wrote; “scarcely does a small cloud, passing across the zenith . . . cast its shadow on the earth. Under the vertical rays of the never-clouded sun, the carbonized turfy covering falls into dust, the indurated soil cracks asunder as if from the shock of an earthquake. . . . Everywhere the death-threatening drought prevails, and yet, by the play of the refracted rays of light producing the phenomenon of the mirage, the thirsty traveler is everywhere pursued by the illusive image of a cool, rippling, watery mirror.”

  Dead palm trees, shorn of their branches, jut from the sand like the masts of sunken ships, and the traveler is tormented by dust storms: “Like conical shaped clouds, the points of which descend to the earth, the sand rises through the rarified air in the electrically charged center of the whirling current; resembling the loud waterspout dreaded by the experienced mariner. The lowering sky sheds a dim, almost straw-colored light on the desolate plain. The horizon draws suddenly nearer; the Steppe seems to contract, and with it the heart of the wanderer . . . ,” Humboldt admitted. “Half concealed by the dark clouds of dust, restless with the pain of thirst and hunger, the horses and cattle roam around, the cattle lowing dismally, and the horses stretching out their long necks and snuffing the wind, if happily a moister current may betray the neighborhood of a not wholly dried up pool. More sagacious and cunning, the mule seeks a different mode of alleviating his thirst,” by carefully scraping the thorns off the melon cactus with its hooves to get at the cool juice inside. Though temperatures abated when the sun went down, at night the hapless animals were preyed upon by enormous vampire bats, who opened wounds in the sleeping creatures’ backs. The bats also hovered over the hammocks, threatening at any moment to affix themselves to the faces of the human travelers.