Naturalist 25th Anniversary Edition

by Edward O. Wilson

  At every opportunity I collected ants. I would rush ahead a few hundred meters, work for a few minutes, and fall in again as the others came by, or linger behind the bearers to work promising patches of forests and clearings, then walk fast or jog to catch up. I ventured from the villages at trail’s end to work nearby habitats in the fading afternoon light. When we stayed in one place for two or three days, as at Gemeheng and Ebabaang, I left on more distant excursions. My worst problem was the weather: on most days afternoon mist and sporadic light rain settled throughout the mountain country. Most of the time, day and night, the temperature swung between a chilly 10° and barely comfortable 20°C. Only near midday in open sunny ground did it rise to the upper twenties, and it was under these conditions that ants were most numerous and active.

  I was also hampered by the oppressively curious and helpful Hube people. Because I spent so much time in the forest, they called me “bush man.” In the early days I was accompanied by mobs of boys of all ages and a few men, who pressed in so closely to see what I was doing that I could barely work. When they understood my purpose, they began to hunt for me, with the result that all the nearby logs and stumps were quickly torn to pieces with little result. I started telling them, as politely as I could, to stay away. But on several occasions I asked my retinue to collect spiders, frogs, and lizards and to ignore the ants and other smaller insects I was picking up myself. They scattered in all directions and in short order filled all the spare bottles I carried. I remember especially one boy, about twelve years old, who ran up to me clutching a giant silk spider in one hand, its fangs gnawing at a callused pad on his thumb. Grinning widely, he held it up for me to take. I am a bit of an arachnophobe, and for an instant I panicked. Then I grinned widely myself and held out my open lunch bag to receive the monster.

  To my relief, we never caught the murderers. We also failed to make it to the high Sarawaget. At Buru a runner from Finschhafen brought Curtis a message: he was to report to Port Moresby as soon as possible to be interviewed for another, better-paying position. The next day we turned southward along the Bulum River, away from the Sarawaget and toward Butala on the coast, where a truck had been reserved to carry us the rest of the way to Finschhafen. As I walked homeward one day during this final leg I experienced an insight about the diversity of tropical ants. All through my stay in New Guinea I had studied long stretches of relatively undisturbed rain forest, first at the Brown River, then at the Busu River near Lae, and now partly along the length of the Huon Peninsula. I had paid close attention to the identity and relative abundance of all the ants I could find, writing notes on every colony. I noticed that although the forest seemed to change very little in outward appearance from one kilometer to the next at the same elevation, the composition of the ant fauna usually shifted in a striking manner. It was possible to find, say, fifty species in one hectare, and another fifty species in a second hectare a short distance away, but at most only thirty or forty of the same species occurred in both places. Some of this variation was due to a local change in the physical properties of the habitat: the second hectare, for example, might contain a small sago palm slough or a clearing caused by a falling tree. That is the kind of easily understood change ecologists now call beta diversity—variety in species based on local differences in habitat. But much of the shift could not be so easily explained. It represented what is today called gamma diversity, the changeover in species with growing geographic distance.

  The pattern I observed was very different from that in temperate forests, where gamma diversity occurs to the same extent only over tens or hundreds of kilometers. I had discovered something new about the structure of ant faunas in the tropics, and perhaps about the origin of the fabulous diversity of rain forest faunas and floras as well. In 1958 I concluded a formal article on the subject as follows:

  In any appraisal of comparative ecology, the New Guinea ant fauna is first of all to be characterized by the exceptional richness of its species and the great size of its biomass … In addition to sheer size, an additional factor adds greatly to the total faunal complexity. This is the discordant patchy distribution of individual species … As a result of discordant patchiness, no two localities harbor exactly the same fauna. Considering that several hundreds of species are thus involved, it is clear that the spatiotemporal structure of the entire New Guinea fauna must present the appearance of a great kaleidoscope. The effects of such a structure on the evolution of individual species of ants, as well as of other kinds of animals, must be considerable. It very possibly hastens the genetic divergence of local populations and plays an important role in the “exuberance” and amplitude that characterize evolution in the tropics.*

  I later learned that André Aubreville and Reginald Ernest Moreau had earlier and independently noted similar patchiness in African rain forest trees and birds. So patchiness is a general phenomenon, as I had hoped in 1955. My own insight was to be an early step in the development of my theory of the taxon cycle and, later, in collaboration with Robert MacArthur, the theory of island biogeography. Most important, it fixed my attention on biological diversity as a subject worthy of study in its own right.

  I felt gratified—indeed, exuberant—that I had discerned what appeared to be a broad ecological pattern from my undisciplined collections and journals. But this was the way it is supposed to be. Nature first, then theory. Or, better, Nature and theory closely intertwined while you throw all your intellectual capital at the subject. Love the organisms for themselves first, then strain for general explanations, and, with good fortune, discoveries will follow. If they don’t, the love and the pleasure will have been enough.

  This insight came to me at Wamuki, which faces southward on the mountain ridge separating the Bulum Valley on the west from the Mongi Valley on the east. A day’s walk farther south, the two rivers converge to form the greater Mongi, which runs on to the sea at Butala. As I strolled back at dusk one day at the end of one of my final excursions, I watched the clouds clear over the entire Bulum Valley below me. I could then see unbroken forest rolling down to the river and beyond for fifteen kilometers to the lower slopes of the Rawlinson Range. All that domain was bathed in an aquamarine haze, whose filtered light turned the valley into what seemed to be a vast ocean pool. At the river’s edge 300 meters below, a flock of sulfur-crested cockatoos circled in lazy flight over the treetops like brilliant white fish following bottom currents. Their cries and the faint roar of the distant river were the only sounds I could hear. My tenuous thoughts on evolution, about which I had felt such enthusiasm, were diminished in the presence of sublimity. I could remember the command on the fourth day of Creation, “Let the waters teem with countless living creatures, and let birds fly above the earth across the vault of heaven.”

  Central summit ridge, Sarawaget Mountains, May 1955. When I returned to Lae, the administrative center of northeastern New Guinea, at the coastal base of the Huon Peninsula, my mind stayed on the Sarawaget Mountains. Standing in the main street on a clear morning, I could look north all the way to the blue-gray ridge of the center of the range. I learned that no European had ever climbed to the top of this main part of the mountain crest, which thrust up in such plain sight. Eight men, including the ornithologist Ernst Mayr, had independently reached the eastern end of the Sarawaget out of Finschhafen along the route partly traveled by Bob Curtis and me, but none had pushed on west toward the center ridge. In 1955 this lack of exploration did not seem very surprising: the Lae area had been settled only in the 1920s, and when I was there the population of planters, lumbermen, and colonial officials was still small; clearly, they had other things to do.

  I hungered to get to the top of the Sarawaget. I was excited by the possibility of being the first white to visit the center of the crest. The problem was how to get there. Hearing that there was a Lutheran mission at Boana, halfway up the Bunbok Valley between Lae and the summit ridge, I inquired about Boana at the Agricultural Service office and soon received word that the
resident minister, Reverend G. Bergmann, would be glad to have me as a guest and provide native help if I decided to attempt the climb. Bergmann was one of the eight Europeans to have climbed to the eastern end. He believed that it would not be too difficult to reach the middle as well.

  On May 3 I walked into the office of Crowley Airways, the main transportation link to the Bunbok Valley. The president and sole full-time employee, Mr. L. Crowley, was seated behind a battered wooden desk. He rose, we shook hands, he shuffled some papers, and I paid the round-trip fare to Boana, four pounds and ten shillings Australian. A few days later Crowley and I walked across the tarmac to his 1929 biplane for the weekly flight to Boana. He stepped into the forward cockpit and I into the rear passenger cockpit, and we took off for the Bunbok Valley. I enjoyed the open-air, low-altitude view while peering over the edge of the cockpit. I also noticed that the double wings on each side waved up and down slightly throughout the flight. I supposed—hoped may be the better word—that the birdlike movement was a normal part of the airplane’s aerodynamics.

  The approach to the Boana was tricky. The mission was perched on a mountain spur to the east of the valley, and the airstrip could be reached only from the tributary valley by a southward approach. So we flew north along the river, mountains rising on both sides, turned right at the tributary, then immediately turned right again, now pointed south, and there, coming up fast, were the mountain ridge and, plastered on its side, the airstrip. As we glided in for a landing on the grassy surface, I saw the second aircraft of the Crowley fleet, also a 1929 biplane, this one recently crashed and still nose down on the edge of the airstrip.

  In the late morning the Sarawaget crest, blue-gray against a lowering cloud bank, seemed close to Boana, a day’s walk perhaps, and I ached to get started. It was in fact five days’ walk away. I departed two days later, accompanied by a half-dozen young Papuan men hired as guides and carriers. The trip proved to be the physically most demanding of my life. It beggared even the hardest parts of the just-finished Sarawaget patrol. We reached the village of Bandang the first day, then proceeded up into virtually untracked country in daily marches lasting five to seven hours. Seldom were we able to travel for more than a hundred meters in a straight line on level ground. We wove, stumbled, waded, climbed, and sometimes just crawled our way, following stream banks, tracing animal trails up and along the crests of ridges, down into stream valleys and then up again. To my dismay my guides occasionally became lost, and we had to wait while one or two left to reconnoiter higher terrain and reestablish our position.

  Our little party was almost constantly wet from intermittent rain, which set in predictably by early afternoon and continued into the early evening. Our clothing was stained by the soaked and puddled moss-grown earth over which we struggled. Beyond 2,100 meters, the temperature dropped to below 15°C at night and never rose as high as 20° during the day. Land leeches were everywhere—big, aggressive, and black, quickly swelling to half the size of a thumb with fresh blood—and periodically we stopped to take them off our legs and feet. To sit on a muddy stream bank in near exhaustion, pull off boots and peel down socks, and burn free a half-dozen engorged leeches, then watch blood trickle down from the bite wounds: that is an experience best savored after a few years have passed.

  I was afraid, at times, of a crippling accident, of the possible unreliability of my assistants, with whom I could communicate very little, but most of all of the inexpressible unknown. Would I fail from physical incapacity or lack of will? Would I have to turn back as I did in Mexico, short of the Orizaba snowfield? Why had I come here anyway, except to be able to say I was the first white man to climb the central Sarawaget? That prideful goal was part of the truth, but I was looking for something more. I wanted the unique experience of being the first naturalist to walk on the alpine savanna of this part of the Sarawaget crest and collect animals there. And I wanted release from the mountain-peak compulsion that gripped me. I decided to keep going, even if I crawled or had to be carried.

  Slogging on, we began to pass from the midmountain rain forest into mossy forest at about 2,000 meters. Here ferns, orchids, and other epiphytes thickly encrusted the branches and trunks of low gnarled trees. By 3,000 meters moss flowed like a continuous carpet from the trunks onto the forest floor. The canopy was also low here, only five meters above the ground, so in places progress was restricted to wide tree-tunnels with mossy floors, walls, and roofs. Then at 3,200 meters, as we worked up at last onto the central ridge, the moss forest began to give way to scattered patches of Eugenia shrubs and alpine grasses.

  Early on the fifth day, before the inevitable clouds descended and cold rain began to fall, we walked the final two hours to the summit. Here, at 3,600 meters, we were in a savanna composed of tall grass sprinkled with cycads, squat gymnospermous plants that resemble palm trees and date from the Mesozoic Era; a very similar scene might have existed here 100 million years before. The ground was mostly a mountaintop bog difficult to navigate. I made it on up to the nearest high point, sat down, wrote my name and the date on a scrap of journal paper, put the memento in a tightly capped bottle, then buried the bottle beneath a cairn of small rocks. From that position I could look south all the way down to the grasslands of the Markham Valley and the more distant Herzog Mountains, and north to the Bismarck Sea. Zigzagging back down the savanna, I collected every insect I could find, as well as small frogs that turned out to be a new species, while my companions hunted alpine wallabies with bows and arrows and dogs.

  Then we turned back and began the two-day return trip to Boana, a far easier trek than the climb up. As we fast-walked and slid our way down the ridges and into the upper Bunbok Valley, something resistant and troubling finally broke and receded inside me. The Sarawaget, cold and daunting, had proved a test of my will severe enough to be satisfying. I had reached the edge of the world I wanted, and knew myself better as a result. By passing from the sea to its peaks I had finally encompassed the serious tropics of my dreams, and I could go home.

  *“Patchy Distributions of Ant Species in New Guinea Rain Forests,” Psyche 65(1) (1958): 26–38.

  chapter eleven

  THE FORMS OF THINGS UNKNOWN

  FROM NEW GUINEA I CONTINUED MY JOURNEY WESTWARD on around the world. After pausing for a week of field work in the rain forests of Queensland, I boarded an Italian liner in Sydney that carried me south around the Victoria coast and then west along the Bight to Perth. From this most distant city on Earth from my home, the ship churned slowly north across the Indian Ocean toward its eventual destination of Europe. I got off at Ceylon, now the republic of Sri Lanka—in any case the island “Pearl of Asia” that hangs like a teardrop from the tip of India.

  I traveled inland from the port of Colombo to search for one of the rarest ants in the world. Aneuretus simoni is the apparent evolutionary link between two of the great worldwide groups of ants, the Myrmicinae and Dolichoderinae. Fifty million years ago the group to which it belongs, the Aneuretinae, abounded throughout the northern half of the world. Now only one species remains, the endangered Aneuretus simoni. I began my quest in the Botanic Gardens at Peradeniya, where the only specimens in museums had been collected around 1890.

  I hoped to find Aneuretus at the original find site, near the center of the island. No luck; the place had been shorn of native vegetation. For three more days I worked without result in the forest of the neighboring Udawaddatekele Sanctuary, close to Dalada Maligava, the temple holding a giant tooth said to be that of Buddha. Unrewarded by His blessed aura, I took a bus south to the gem center of Ratnapura. There, somewhere in the remnants of rain forest scattered along the road to Adam’s Peak, Sri Lanka’s highest elevation, the prize might be found. I checked into the government rest house, eager to get started. Dropped my Army-issue duffel bag in my room. Swung my stained canvas collector’s bag over my shoulder. Walked down the stairs and out the back entrance a hundred meters to a line of trees fringing the town reservoir. Looked around. Picke
d up a dead twig lying on the ground, broke it open, and stared as a colony of small, yellow ants ran out over my hand. Aneuretus! I could not have been happier if I had discovered a priceless Ratnapura sapphire lying unclaimed on the ground. Settled back in my room, I turned the vial of specimens slowly over and over in my hand, looking at the first queen, larvae, and soldiers of the living aneuretine ever seen (the 1890 specimens had all belonged to the worker caste). This was one of the great thrills of my life. Dinner tasted fit for a gourmet that evening, and afterward, sleep came easily.

  In the days that followed, I ventured into forest closer to Adam’s Peak. Though sometimes delayed for hours by monsoon downpours, the kind called gully-washers or frog-stranglers back home, I easily secured more colonies, finding the Aneuretus in one locality to be among the most common ants. In a short while I was able to put together a picture of the social life of the last surviving aneuretine. Twenty years later one of my undergraduate students, Anula Jayasuriya, a native Sri Lankan, found the species rare or absent in the same localities. I recommended placement of Aneuretus simoni in the Red Data Book of the International Union for Conservation of Nature and Natural Resources, and in time it became one of the first of several ants to be officially classified as a threatened or endangered species.

  My field adventure was now finished. I continued on by a second Italian liner (cheap fare) to Genoa, where I worked on the ant collection of Carlo Emery at the Museo Civico di Storia Naturale. Then I proceeded by train across Switzerland and France and finally to London, visiting other ant collections in museums along the way. That was my European tour as a young academic: the great ant collections of the world. When others at Harvard spoke of their experiences at Hagia Sophia and the Prado, I reminisced about the wondrous ants I examined in Geneva and Paris.