In late July, accompanied by Robert Dressler, Quentin Jones, and Methuselah, I flew from Havana to Merida, on Mexico’s Yucatan Peninsula. We departed immediately for a week’s collecting in the thorn forest along the Progreso-Campeche Road, with a side trip to the ruins at Uxmal. We found the great temples and courtyards of the Mayan city only partly cleared of vegetation. No tourists or guides were present, and we enjoyed a free run of the grounds. Ants abounded on and among the crumbling edifices, as no doubt they had done 1,400 years previously when the first stones were laid. I climbed the stairs of the Temple of the Magician to a fig tree growing on its apex, and from the branches of the tree collected workers of Cephalotes atratus, a large, shiny black ant with compound spines. Resting briefly by the tree, I reflected on this triumph of the ever-abounding life of insects over the works of man.
We next flew out of Mérida to Mexico City, where I left Dressler and Jones and began a solitary all-entomology expedition. I took a bus eastward, through the pine-dotted uplands of the Mexican Plateau and down the winding road that drops thousands of feet to the coastal plain and city of Veracruz. I arrived for the first time in what I like to call the serious tropics: not the island habitats of the West Indies, with their eccentric and interesting but limited fauna and flora; not the mangrove fringes of the Florida Keys and Caribbean coasts, however verdant; but the inland continentallowland tropics, the true Neotropics, with its vast biota deployed in endless combinations of species from Tampico in Mexico through Central and South America to Misiones Province in northern Argentina. Here in almost any patch of moist forest I could find more species of ants in an hour than would be possible in a month’s travel through Cuba.
I searched for residues of the vanishing rain forest along the coast, finding them in the vicinity of El Palmar, Pueblo Nuevo, and San Andrés Tuxtla. All were under heavy siege, already cut back along the edges and high-graded in the interior. Off the highway other such refugia could be seen on distant hilltops and the slopes of steep ravines. Such was and remains the pattern of access left to visitors everywhere in the tropical world. It can be expressed in the form of a standard route: leave the road, climb through a barbed-wire fence, hike across a pasture, and slide down a slope to the edge of a stream. Cross the stream—if it is shallow enough—and start up the other side to the edge of the forest. Cut through fringing second growth until you reach the shade of trees. At this point you have arrived at your destination but are likely to be on an incline so steep that it is necessary to hold on to the trunks and exposed roots of bushes and small trees to avoid tumbling head over heels back down to the bottom.
How much longer will these precarious refuges last until they too are cut away? It was frustrating and heartbreaking to travel in Mexico with such thoughts in mind. When at last I made it into the rain forests of Veracruz State I operated like a vacuum cleaner, taking samples of every kind of ant I could find. At night I identified species, labeled my vials, and wrote natural history notes. I had remarkably quick success by entomological standards: I captured colonies of two genera, Belonopelta and Hylomyrma, that had never been studied before, and recorded my observations on their social organization and predatory behavior for later publication.
As I prepared to leave the Veracruz coast two weeks later, my attention was drawn to Pico de Orizaba, the great volcanic mountain just north of the city of Orizaba. Its beautiful symmetric cone rises 5,747 meters—18,855 feet—above sea level to a permanently snow-covered peak. Orizaba is not just a prominence atop an already towering mountain range or plateau like Popocatepetl and mighty Aconcagua, but a mountain of more solitary and mystic qualities, a lone giant born of Mexico’s ring of fire, standing sentinel over the southern approaches of the central plateau.
I was drawn not just by the amazing sight but also by the very concept of Orizaba. I thought of the mountain as an island. It was isolated from the plateau, yet I believed that a lone climber could travel in one relatively short straight pass from tropical forest to cold temperate forest and finally into the treeless arctic scree just below the summit. The cooler habitats constituted the island. The surrounding tropical and subtropical lowlands were the sea. Orizaba’s uplands were close enough to the plateau to receive immigrant plants and animals adapted to the middle and upper slopes, yet isolated enough for unique races and species to have evolved and dwell only there.
So what might I hope to discover if I climbed Orizaba? No one had toiled up the slopes of the mountain to study ants, generally the most abundant of small terrestrial animals, with the possible exception of the much smaller mites and springtails. For every bird there might be a hundred thousand or million ants, and I could reasonably expect to sample the species effectively during a single fast traverse. I knew that the change in fauna and flora from tropical to temperate was likely to be dramatic. The southeastern face of the Mexican escarpment, where Orizaba sits, is the site of the most abrupt changeover of biogeographic realms found anywhere in the world, except perhaps in the Indian and Bhutanese Himalayas. On the plateau live large numbers of plants and animals typical of the Nearctic Region, a realm extending northward to encompass all of North America. While descending earlier the tortuous road from Puebla over the plateau to the Veracruz plain, I had left this world of beech, oak, sweetgum, and pine and entered the Neotropical Region, where aroids and orchids cling in masses to arrow-straight tree boles and lianas hang like ropes from the lofty horizontal branches.
I expected to find all this and more if I climbed Pico de Orizaba. Let me put it more strongly: I was foreordained to try it. I would start at La Perla, at 3,000 feet, and follow a donkey trail I had heard about to the hamlet of Rancho Somecla, at 11,000 feet. I would simply ask for the hospitality of the people there, who were rumored to be friendly to strangers, and proceed the next day on up to the snow line, at about 16,000 feet. I would collect ants and make notes on the environment all along the way.
I was a fool of course, traveling alone on foot up a high mountain without a map and no more than phrasebook Spanish. But I did make it most of the way. Early in the morning of a beautiful late August day, I took a bus from the city of Orizaba to La Perla and started walking. The mountain’s south slope was mostly uninhabited; I encountered no one on the trail until I reached Rancho Somecla, my destination, late that afternoon.
My journey began in subtropical vegetation. At 5,500 feet I entered a forest dominated by hornbeam and sweetgum, both temperate-zone trees, with tree ferns abundant in the understory. Scattered through the habitat at lower elevations were dense, wet patches of tropical hardwoods. The ants in this transition belt, which composed nothing less than the passage from the Neotropical to the Nearctic regions, were a mix of tropical and temperate species: army ants and fire ants mingled with species of the typical north temperate genus Formica. Two of the Formica species later proved new to science. At 8,000 feet I found a mixture of pines, making their first appearance along the ridges, and broadleafed trees dominated by hornbeam on the slopes. The woodland was tessellated by pastures and stump-filled glades recently cleared by woodcutters.
When I arrived at Rancho Somecla, which turned out to be a collection of about a dozen houses, I was close to exhaustion. To the people who came out to meet me, I explained as best as I could why I was there. I doubt that they really understood my words or gestures, but one family promptly offered me lodging. I rested while they prepared a chicken dinner. Then, as the light failed, I headed out for one more try at ant collecting in the surrounding pine forest, this time accompanied by several young men who listened gravely as I explained why I was tearing up the bark of rotting logs and putting insects in bottles. One of my companions agreed to guide me to the snow line the next day.
That night I slept not at all. My bed was a table, and the single blanket given me offered little warmth when the temperature fell into the forties Fahrenheit. Occasionally I rose to look through the door at the brilliant full moon in a cloudless sky. It would be a wonderful place to live, I
thought, if you brought a lot of blankets.
At dawn the next morning, after pressing some pesos on my hosts, I headed on up the mountain with my guide. When we reached an elevation of between 12,000 and 13,000 feet, we entered open cloud forest, where the pine trunks were gnarled and the branches draped with epiphytes. My excitement was growing, but I could go no further. The air was too thin for someone who had been living at sea level, and I was gasping for breath. I estimate that I had come to within 400 feet of timberline and perhaps 3,000 to 4,000 feet below the snowcap. Of course I was at my physical limit. I had been entirely naive to suppose that anyone could walk three miles from the lowlands straight up into the air in thirty-six hours and keep on going.
In any case ants had become very scarce, even in the clearings warmed by the morning sun. I searched for an hour before finding one colony nesting beneath a wood chip. Then I turned around and started walking back down. At Rancho Somecla I shook hands with my guide and headed alone down the trail to La Perla, moving rapidly now, then to my hotel in Orizaba, where, the sated adventurer, I slept for twelve hours.
PART 2
STORYTELLER
If you’re a storyteller, find a good story and tell it.
HOWARD HAWKS, FILMMAKER
chapter ten
THE SOUTH PACIFIC
ON A COLD MARCH DAY IN 1954, IN THE SEASON WHEN CAM-bridge is its least lovable, Philip Darlington called me to his office. How would you like, he said, to go to New Guinea? The Society of Fellows and Museum of Comparative Zoology had agreed to cover my expenses for an extended visit. No specialist had collected ants in that fabulously rich and still mostly unexplored fauna. Other islands such as New Caledonia might be visited en route. I could work hands on in the very arena where a hundred years before young Alfred Russel Wallace had begun to turn zoogeography, the study of animal distribution, into a scientific discipline. Who knows how the experience might transform my own thinking as a zoogeographer? And if I picked up some ground beetles, Darlington’s favorite group, that would be all right too.
Here was the brass ring for a young field biologist. Many years were to pass before another generation of well-funded researchers were to descend in teams on New Guinea and other South Pacific islands and set up field stations. I could be a pioneer. Darlington said, Go, while you’re still footloose and fancy-free.
I was not footloose and fancy-free. I was in love. The previous fall I had met a beautiful young woman, Renee Kelley, from Boston’s Back Bay, and we were engaged to be married. She was a fellow introvert, pleasured by long hours of quiet conversation, a budding poet, deeply interested in literature, a scholar by temperament, and thus, though not a scientist, able to understand my dreams of pursuits in faraway places. Our marriage was to be happy and enduring.
We were young then, in 1954, and a parting seemed almost unbearable at the start of our engagement. But we agreed I should go to New Guinea. I would be away ten months, much of the time in remote areas. No jetliners existed then to shuttle me back and forth, and the great distance and high costs of transportation by other means made interim visits improbable. Telephone calls were difficult and expensive, to be used only for emergencies.
On the morning of November 24 the Eastern Airlines carrier to San Francisco taxied from the gate at Boston’s Logan Airport and out onto the runway. I could see Renee pressed to the visitors’ observation window, her right hand waving slowly. Around her neck she wore a long woolen scarf striped in Harvard maroon and white, its tasseled ends nearly touching the floor. We were both weeping. Divided by two passions, the tropics and romantic love, I was a young seafarer venturing into another age on a long and uncertain voyage. Until I came home we would write to each other daily and at length, accumulating a total of some six hundred diarylike letters.
I had decided on a tour of the outer Melanesian archipelagoes, then Australia, and finally New Guinea. From San Francisco I took a propeller-driven Pan American Super Constellation across the Pacific. It touched down for refueling at Honolulu and Canton Island—a dry, cheerless atoll in the Phoenix group—before proceeding to Fiji. As it descended toward Nandi Airport in Viti Levu the next morning, I looked down upon a passage of white and green atolls in a turquoise sea. Never before or afterward in my life have I felt such a surge of high expectation—of pure exhilaration—as in those few minutes. I know now that it was an era in biology closing out, a time when a young scientist could travel to a distant part of the world and be an explorer entirely on his own. No team of specialists accompanied me and none waited at my destination, whatever I decided that was to be. Which was exactly as I wished it. I carried no high-technology instruments, only a hand lens, forceps, specimen vials, notebooks, quinine, sulfanilamide, youth, desire, and unbounded hope.
The South Pacific is a galaxy of thousands of islands, spread out in configurations that have served many of the key advances in evolutionary biology. Darwin conceived of evolution by natural selection from what he learned about birds in the Galápagos Islands, and Wallace had the same idea after studying butterflies and other organisms in the old Malay Archipelago, now modern Malaysia, Brunei, and Indonesia.
A true, biogeographic island, I knew as I stepped off the plane at Viti Levu and looked around, is a world that holds most of its organisms tight within its borders. It is the ideal unit for the study of evolution. Enough immigrants fly, swim, or drift ashore to colonize the island, yet not so many in each generation to form the commanding elements of its populations. If the island is large and old and distant enough, the descendants of the immigrants evolve into new races peculiar to the new home. Given enough time the races diverge still further from their sister populations on the continent and on neighboring islands to deserve the taxonomic rank of species. We speak of such local races and species as endemic: they are native to the island and nowhere else in the world. The Hawaiian hawk is a good example of an endemic, as well as the Jamaican giant swallowtail and the Norfolk Island pine. By factoring in the age of the island and the origin of the immigrants, biologists can reconstruct the evolution of the plants and animals there more easily than on continents. The simplicity of islands makes them the best of all natural laboratories.
The experiments are conducted in opposite manner from those in conventional laboratories. They are retroactive rather than anticipatory. Whereas most biologists vary a few factors under controlled conditions and observe the effects of each deviation, the evolutionary biologist observes the results already obtained, as learned from studies of natural history, and tries to infer the factors that operated in the past. Where the experimental biologist predicts the outcome of experiments, the evolutionary biologist retrodicts the experiment already performed by Nature; he teases science out of history. And because so many factors may have operated in the guidance of evolution and the creation of wild species, the best result of the retrodictive method can be obtained if the ecosystems are relatively small and simple. Hence islands.
Unlike experimental biologists, evolutionary biologists well versed in natural history already have an abundance of answers from which to pick and choose. What they most need are the right questions. The most important evolutionary biologists are those who invent the most important questions. They look for the best stories Nature has to tell us, because they are above all storytellers. If they are also naturalists—and a great majority of the best evolutionary biologists are naturalists—they go into the field with open eyes and minds, complete opportunists looking in all directions for the big questions, for the main chance.
To go this far the naturalist must know one or two groups of plants or animals well enough to identify specimens to genus or species. These favored organisms are actors in the theater of his vision. The naturalist lacking such information will find himself lost in a green fog, unable to tell one organism from another, handicapped by his inability to distinguish new phenomena from those already well known. But if well equipped, he can gather information swiftly while continuously thinking, ev
ery working hour, What patterns do the data form? What is the meaning of the patterns? What is the question they answer? What is the story I can tell?
This is the strategy I brought with me to the ant fauna of the Pacific Islands. I would collect samples of every species I found and write notes on all the aspects of ecology and behavior I observed, all the while watching for patterns in the form of geographic trends and adaptation of species to the environment. I was well aware of existing theory and the conventional wisdom of my discipline, but I would hold my mind open to any phenomena congenial enough to enter it.
Nadala, Viti Levu, December 1954. Fiji in one dreadful sense was Cuba and Mexico all over again: the native biota had already been driven back to scattered and nearly inaccessible enclaves. At Nandi I hired a driver and traveled along the north coast road of Viti Levu through villages, domestic groves, and pastureland. Virtually no natural forest survived along this thoroughfare, crowded as it was by the dense settlements of immigrant East Indians. We turned south at Tavua toward the central hills to search for patches of native forest, all on the land of the aboriginal Fijian population. One elderly man I met remembered another ant collector who had visited nearby Nandarivatu forty years back. He could not recall the name, but I knew it was William Mann, also my predecessor in Cuba, sent by Harvard to the islands in 1915–16 to collect for the Museum of Comparative Zoology. The forest I could reach in one day was similar to what he had known except that it had been disturbed by high-grade lumbering and perforated by slash-and-burn clearings. At Nadala I crawled up a steep slope over scattered pumice rocks to a well-shaded pocket of native trees, densely hung with lianas, where I found elements of the endemic ant fauna. One of them shot adrenaline into my veins: Poecilomyrma, a genus known solely from Fiji and collected only one time previously—of course by William Mann.
Naturalist 25th Anniversary Edition Page 14