From bugs to boas, Dan Janzen bags the rich coast's life

Don Lessem
Smithsonian

December 1, 1986

From bugs to boas, Dan Janzen bags the rich coast's life A two-inch-long, thickly furred caterpillar, captured moments before in the Costa Rican rain forest, is squirming across Dan Janzen's hand under the uneasy gaze of 20 biology students. "Many caterpillars of saturniid moths have spines that are highly irritating to predators," he explains before popping the creature into his mouth. "But this butterfly caterpillar is a harmless mimic."

Such are the parlor tricks of University of Pennsylvania professor Daniel H. Janzen, perhaps tropical biology's leading educator and theorist, and likely its most eccentric and energetic character. Here on the forested slopes of a volcano overlooking the Nicaraguan border or back on campus, these University of Pennsylvania students can expect many more dramatic displays from their instructor.

In the pursuit of a lecture point, Janzen has been known to leap onto tables or climb trees, and in his insatiable quest for information on tropical species he has pulled a seven-pound baby deer from the stomach of a six-pound, five-foot-long boa constrictor, weighed both, then stuffed the deer back in the boa like dirty laundry into a duffel bag (p. 114). More uncomfortable was the warble-fly larva he allowed to burrow into a grow up in his leg (their eggs are carried on the bellies of tropical mosquitoes, and the larvae hatch onto the skin of a human or a cow) to better understand its behavior.

It's all in a day's and a life's work for the 47-year-old,20-year researcher in Costa Rica and the man called the "dean of tropical biologists" by the likes of both Pulitzer Prize-winning Harvard biologist Edward O. Wilson (On Human Nature) and best-selling author and Stanford biologist Paul Ehrlich (The Population Bomb). Standing in a cattle truck headed down the mountain, shouting out landmarks to his companions, his thinning hair flying, Janzen looks less an academic than a prophet. Indeed, his flowing beard and fierce gaze suggest John Brown at Harpers Ferry.

Janzen's attire suggests neither prophet nor professor, but garage mechanic. In the forest, as in the halls of academe, his daily garb is muddy boots, dark work shirt and pants, key chain and snake bag dangling from the belt. At Penn's biology laboratories he is frequently mistaken for a janitor. When buying a suit and borrowing a tie in 1984, to accept the Crafoord Prize, biology's Nobel, from the Royal Swedish Academy of Sciences, Janzen did not own either.

Nor does he favor the cozy, donnish home life during the six months of every year spent at Penn. He doesn't even have a home there. Rather, he'll curl up on a cot in his crowded lab, sandwiched between the display cases and the bags of mot cocoons.

At home with Winnie, Squintle and two computers

Janzen's chief residence for the past 14 years has been a small, rented, tin-roofed cabin in Santa Rosa National Park on Costa Rica's Pacific coast. These quarters he now shares with his companion of seven years, Winnie Hallwachs (p. 118); two Macintosh personal computers; a pet paca, Squintle (from the dog-size rodent's Aztec Indian name, tepiscuintle); and even more bags of moth larvae and pupae (opposite).

A Ben Franklin quote on the cabin door proclaims, "The idle are not only useless but pernicious members of society." Sloth has never been one of Janzen's vices. Here he's up at dawn and out in the field, and in Santa Rosa the field is often just that. Though tropical biology is largely concerned with the unparalleled riches of the dark and verdant rain forests, his domain looks more like an African savanna or Missouri woodlot. Nevertheless, this small and mostly dry patch of partly deforested pastureland contains the largest parcel of tropical dry forest (as its deciduous, seasonally wet woodlands are known) in western Central America. And Janzen's goal is, as he simply puts it, "to understand how this forest works."

To understand the challenge that statement represents, consider that Janzen counts on his 39-square-mile backyard at Santa Rosa 3,140 species of caterpillars, 170 species of resident land birds, 115 mammal species, 100 reptile and amphibian species--as many of each group as are found in the eastern United States. Spectacular wildlife is all around; brilliant parrots, jaguars, peccaries and, in fall, a beach so packed on some nights with egg-laying marine turtles that he could walk for miles across the strand on their backs.

Yet Santa Rosa is somewhat faunally impoverished compared to the 40 percent more-species-rich lowland rain forests of Costa Rica and elsewhere in the tropics, a thin and narrowing green belt across the Eart's middle that holds more than half of its species. "The complexity of New York City is to a square mile of lowland tropical forest as a mouse's squeak is to all music that has ever been produced by humanity," Janzen has written.

In his desire to understand that score, he attends every mouse's squeak. Few tasks are too dangerous boa-battling included, and none too tedious or distasteful in his quest to understand predator-prey relationships. So when he comes across a large and highly toxic toad, Bufo marinus, on his fast and frequent walks through Santa Rosa, he'll rapidly make it disgorge its lunch and then he'll examine the contents. On encountering mouse, coyote or horse scat, regardless of what he's doing or with whom, he'll pause to search for evidence of prey consumed or seed dispersed.

His colleague Hallwachs (a Cornell University biology graduate student) shows equal enterprise with her favorite subject, a rabbit-size rodent, the agouti. She has put bobbins on thread inside hollowed hard fruits and followed the thread trail to map agouti cache sites.

More like the naturalists of the past century than the scientists of this, Janzen and Hallwachs seek to catalog. But classifying tropical fauna is a far more daunting task than temperate-zone systematics. Just what they are up against and after in their personal inventory of the tropics can be glimpsed from one of their study projects: the census of all the month species of Costa Rica. For eight years, Janzen, Hallwachs and Costa Rican assistants have been collecting moths monthly from 24 sites across the country. Several moonless nights a moth they set out lights against sheets to attract male moths (p. 115). So far they have captured, dried and pinned (Janzen uses almost every spare moment, including seminars of colleagues, to do the last) 250,000 individual moths and are putting thousands of speciments in the Smithsonian's Museum of Natural History and other national collections. When will the census be complete? "In about 30 years, or just about when I die," Janzen predicts, "if we're lucky."

Why bother? "It isn't just for the personal satisfaction take in knowing you can do this sort of inventory in the tropics," he says. "Caterpillars are the major consumers of tropical-forest plants. You can't identify caterpillars without knowing moths, and you can't make any sense out of all the moth observations scientists make in the tropics without classifying them."

Yet collecting observations regardless of subject is his stock-in-trade. "Most biologists develop a hypothesis and then use nature to test it. I get my theories and my results from walking through nature. What I see are interactions beyond imagination, complex ideas and interactions one couldn't dream up."

Stumbling upon an intimate relationship

The ant and the acacia are a case in point. Janzen noticed that the ants occupied the trees, but made no sense of it until he accidentally removed an ant colony that lived in an acacia's thorns and serendipitously encountered the hapless tree weeks later, with its leaves eaten off by insects. Then he found that an English mining engineer, Thomas Belt, had seen and concluded the same thing in Nicaragua in the mid-19th century. Both men were taken by the sugar-producing nectaries on the acacia leaves, the large inflated thorns that the ants had converted to dwellings (right) and the protein-rich food bodies on the leaflet tips.

Janzen observed that species of ant-harboring acacias suffered far less leaf damage from other predators than did naturally ant-free acacia species. In an elegant series of experiments in Mexico and Santa Rosa he showed that ants repelled insects and encroaching plants on the acacias in which they lived. He theorized, in an influential 1966 paper, that this relationship was an example of "co-evolution." He explains, "One organism has changed in response to another, which in turn has changed in response to the first." The ants can't live without the acacias, nor the acacias without their ants. Such one-on-one examples of evolutionary adaptation are most conspicuous in the tropics but some are close to home, such as the cow's rumen full of protozoans that do most of the digesting for her. Janzen's discovery was at the roots of a host of new theoretical inquiries into the workings of evolution.

The importance of the ant-acacia study was noted in the wording of the Crafoord Prize for "imaginative and stimulating studies on co-evolution which have inspired many researchers to continued work in this field." Janzen, however, in typically blunt terms, says his contribution is "highly overrated. I didn't discover the ant-acacia relationship, Belt did. And co-evolution is of no large significance. It is just a human way of relating to evolution--animals protect plants like we protect domestic animals. I don't think I have much to offer theoretical evolutionary biology." To him "all the ant-acacia story does is allow one to see what happens to plants that don't have chemical defenses. Ants are analogous to the tannins in oak trees but you can't take those away and see what happens to the oak."

"Poking my way through complex interactions, telling stories and reporting natural history are what interest me," says Janzen. And the "story" of ants and acacias is but one of hundreds in his repertory. His tales have been reported in some 250 scientific writings ranging from perhaps the shortest paper in the history of science (a whimsical "Yes? No" in the journal Biotropica) to one of the most thorough collections (he was editor and chief contributor among 174 authors in the 816-page Costa Rican Natural History). He writes nature stores as he tells them, in an uncommonly lively style, quoting Pogo on the chief enemy of rain-forest survival ("He is us") and providing an evolutionary answer to Pooh's question on herbivory ("Why do all the good things which an animal likes have the wrong sort of swallow or too many spikes?"). "Herbivores selected the plants to be that way," he writes.

The questions, large and small but never obvious, that Janzen asks himself while looking at the forest become the subjects and titles of his papers. "Why Don't Ants Visit Flowers?"--perhaps because the flowers produce nectar with substances noxious to ants, he postulated. "How Accurate Was the Carat?"--he weighed hundreds of carob seeds, the original basis for the 200-milligram measure, and found that only 78 percent were carat weight. "Why Tropical Trees Have Rotten Cores" may have to do with the hollow boles attracting animals that defecate nutrients. The answer to "Why Food Rots" is that microbes have evolved to work quickly and unpleasantly to beat animal competitors to the prized food source.

Though he's researched in the rain forests of Cameroon, Malaya, Uganda, Mexico and Australia, most of Janzen's papers begin with observations he makes at Santa Rosa, though they can end very far afield. One of the most far-ranging of his hypotheses was that giant and now extinct mammals of the Pleistocene age and earlier were, by their fruit-eating and seed-distributing habits, responsible for much of the past structure of American tropical forests. The relative scarcity today of the large-fruited trees beloved by bygone behemoths is directly related to the animals' extinction 10,000 years ago. He came to this sweeping conclusion while poking through the dung of a large mammal, the horse, and finding seeds of tropical tree fruits eaten many miles and months earlier.

This "Pleistocene megafauna" story, like many of his other published notions, has met with some opposition from colleagues. While once viewed as simply tossing off his ideas, Janzen is now seen as one who backs up his theories with abundant field data. "Some of his early stuff may have been half-baked," says an admiring E. O. Wilson, "but a lot of the criticism now mayarise from professional jealousy over how much he publishes." To a former pupil, World Bank Senior Environmental Affairs Officer Robert Goodland, he is a theoretical Johnny Appleseed, "planting more ideas than a hundred other biologists. Some of them don't take, but most of them do."

Janzen's greatest contributions to tropical biology may be the scientists he has advanced. In his first year in Costa Rica, 1965, he designed the course in tropical biology, an eight-week field approach administered by a consortium of 40 U.S. and Costa Rican institutions, the Organization for Tropical Studies (Phenomena, July 1986). Though Janzen gave up teaching the course nearly 15 years ago, it is still taught as it was designed--students meeting and learning from experts in the wild. Most American tropical ecologists have taken the OTS course and hundreds have come to share his passion for studying the tropics.

He has continued to spread his message personally, as a prize-winning lecturer at the University of Michigan and now at Penn. His field courses at Santa Rosa attract not only graduate and undergraduate students from the university but scholars from Scandinavia as well. But educating college students is now of lesser importance than reaching a younger audience--Costa Rican schoolchildren. The nation is among the world leaders in conservation (more than ten percent of Costa Rican land is protected in national parks; the United States' figure is but one percent), and he credits "biology courses taught 20 years ago in Costa Rican schools with influencing the nation's leaders of today." To further that influence, Janzen and OTS have arranged to reprint Costa Rican Natural History in Spanish at such a low cost that the country's school-children can have their own copies.

Janzen himself received no early formal training in biology. He did, however, acquire a knowledge of hunting and a concern for natural resources from his father and namesake, a former director of the U.S. Fish and Wildlife Service. A somewhat solitary child, young Dan began collecting moths at the age of nine, and did so with such devotion that he made a butterfly-collecting trip to Mexico, his first taste of tropical biology, at 15. As a University of Minnesota undergraduate he supported himself, his then wife and young child by scholarships and hunting and trapping. "I caught all the meat we ate in the last two years," he recalls. He has lost his taste for hunting, if not for collecting insects. But he might never have considered doing the latter professionally had he not strolled inadvertently into a University of Minnesota zoology hall containing mounted birds. From this it was only a step to thinking about his own collection. "Until then," he says, "I was an engineering major. It hadn't occurred to me that you could make a living studying insects." He needed a U-Haul to transport his insect collection to Berkeley when he enrolled at the University of California as a graduate student in entomology.

It was geographic love at first sight

While pursuing his graduate-thesis work, Janzen was invited to a biology course in Costa Rica that was supported by the National Science Foundation. It was a case of geographic love at first sight. "Costa Rica had four times the tropical forest then that it has today," he comments. "It was fantastic, as if what had existed in Mexico 6,000 years ago had survived intact."

The continued survival of large portions of that wilderness is his number-one concern. A trusted advisor to the Costa Rican government ("He is one of our national resources," says former National Parks director Alvaro Ugalde), Janzen recently surveyed ecological damage to one large and remote park caused by illegal gold mining. His recommendation--eviction of hundreds of miners after a major public-education program--was enacted in an unprecedented governmental action last winter.

As "probably one of the best articulators we have of the value of tropical conservation" (according to Thomas Lovejoy, World Wildlife Fund-U.S. Executive Vice President), the message Janzen brings Costa Rican officials is the same one he gives his students and readers worldwide: "If we let the tropics go under we will have committed the greatest criminal act that life on Earth ever could or will sustain." In support of his cause, he often metaphorically turns to the kitchen. "Corn, cows, eggs, orange juice, sugar, coffee (the list goes on)--80 percent of what we eat in a week is of tropical origin. And so are we." Yet, in as little as 30 years--or about the time we will lose Dan Janzen, by his reckoning--"we will have destroyed all of the tropical forests that produced these resources, except for what little is preserved in small parks."

Janzen doesn't believe he can "fight the battle against avarice, ignorance and population growth alone" to save the tropical forests, but he is fighting a one-man war to save one corner of that wilderness. Last year he began lobbying among governments and conservation groups in the United States for an $11 million expansion of Santa Rosa National Park. So far he has raised $1 million, but has to make another $5 million by next May. The new 270-square-mile refuge will be named Guanacaste National Park, after the large-fruited national tree (p. 116) and the province in which the land sits. Linking Santa Rosa and neighboring dry forest with the patches of rain forest on nearby volcanic slopes that serve as seasonal refuges for dry-forest insects, mammals and birds would preserve the vitality of the only dry forest in Central America large enough to be adequate for the native plants and animals, and still be "user friendly" to humans.

But beyond preserving the forest that remains, he has in mind to rebuild the forest that has been destroyed. Following methods he has pioneered at Santa Rosa, burning fire lanes around fields to prevent accidental fires from spreading and killing young trees (some planted by Janzen and assistants, others seeded by wild animals), he would reforest Guanacaste National Park. "In 20 years we can make a pasture into closed-canopy low forest. In 200 years we can make a forest that looks like the original, and in 1,000 years we will have a forest that is the original, for all practical purposes."

With practical purpose, Janzen has attacked the Guanacaste project half-time, "eight to ten hours a day, every day." He has donated half of the $100,000 Crafoord Prize to the Guanacaste National Park endowment, and has spent the remainder to electrify Santa Rosa to provide better working conditions for its users. Much of his time in the United States is now spent soliciting support from conservation agencies (the International Program of the Nature Conservancy is administering his appeal) and bringing his case directly to the public via a traveling slide lecture in which he discusses its title statement, "How to Build a National Park."

When Janzen inaugurated the Guanacaste project with a talk at the Smithsonian's National Zoological Park auditorium last February, a packed house heard Zoo director Michael H. Robinson, himself a tropical biologist, introduce Janzen as "one of the great theoretical and field biologists of this century and a man deeply concerned with the fate of the tropics." Few among his many former students in the audience would have taken exception to Robinson's remarks nor to the possibility that he will raise $11 million to save the dry forest. They knew at a glance just how important saving this corner of the tropical forest is to Dan Janzen. He was wearing a suit and tie.

Copyright 1986 Smithsonian Institution

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