Natural Acts

by David Quammen

  We’re talking about an order called Coleoptera, containing 300,000 officially described species. And new beetles are being discovered almost every time some scientist waves a net through a rainforest. (A Smithsonian entomologist named Terry Erwin believes, from his study of jungle canopy in Peru, that there might be as many as 12 million species of beetle.)

  Each of those 300,000 described species conforms to the basic coleopteran pattern: an insect showing complete metamorphosis (progressing from egg to larva, then pupa, then adult) which in its adult form has biting mouthparts, a pair of front wings drastically modified into hard protective covers (called elytra), a pair of lighter rear wings underneath those covers, and an extraordinarily strong cuticle over the whole body that looks like, and functions as, a suit of armor plating.

  Within that basic pattern there is an unimaginable variety of shapes and colors and life strategies—vicious pinchers and rhinoceros horns on the head, anteater snouts, antennae like the most elaborate TV aerial, snapping hinges between thorax and abdomen that allow certain species to turn somersaults, light fixtures for signaling mates after dark, beetles as small as a sesame seed, beetles as large as a mouse, long scrawny beetles and husky broad-shouldered ones, leaf-eaters and fungus-eaters and meat-eaters, some that live underwater in rivers, some that burrow subway tunnels along the cambium layer of trees, some that gather and roll huge Sisyphean balls of dung. They are a very old as well as a very successful group of animals, dating back almost 250 million years, and in that stretch of eons they have had ample time to diversify. But cockroaches are equally old. So are dragonflies. So are sharks. So are lizards. Why, then, are there so cotton-pickin’ many species of Coleoptera? Why 300,000 variations?

  I don’t know. I don’t know of anyone who knows. I’m still waiting for some evolutionary biologist to propose a convincing explanation—but my secret hope is that no one can or will.

  Meanwhile the famed British geneticist J.B.S. Haldane has left us a valuable comment on this subject. Besides being an eminent scientist from a family of eminent scientists, Haldane was well known in the 1930s as a Marxist and a curmudgeon. Oral tradition among biologists records that Haldane was once cornered by a group of theologians. One of them asked what inferences a person could draw from a study of the created world as to the nature of the Creator. Haldane answered: “An inordinate fondness for beetles.”

  As it happens, J.B.S. Haldane also believed that science has great potential as vulgar entertainment. During the 1930s and 1940s he wrote a long series of science essays for the general public, most of which appeared in the Daily Worker. These short pieces had titles such as “Why I Admire Frogs,” “Living in One’s Skeleton,” “Some Queer Beasts,” and (following a case of theft from the British Museum, for which one entomologist went to prison) “Why Steal Beetles?” In spending his considerable wit and his precious working time to produce hundreds of popular essays, Haldane was perhaps the first in a tradition that is now burgeoning: the tradition of scientists who write graceful and accessible essays on scientific subjects for a lay readership.

  Loren Eiseley continued that tradition, and today it is rich with the work of Stephen Jay Gould, Lewis Thomas, Freeman Dyson, Alan Lightman, Robert S. Desowitz, and others. I would love to be able to claim a modest toehold in the same tradition. But I can’t and I don’t. Because I’m not a scientist.

  What I am is a dilettante and a haunter of libraries and a snoop, the sort of person who has his nose in the way constantly during other people’s field trips, asking too many foolish questions and occasionally scribbling notes. My own formal scientific training has been minuscule (and confined largely to the ecology of rivers). Gould and Thomas and Lightman actually do science, in addition to writing about it. I merely follow science. In my other set of pajamas I’m not a biologist but a novelist.

  This autobiographical information is offered not because I imagine it has any inherent interest but in a spirit of disclaimer, an effort at truth in packaging. The following is not a diet book nor a detective novel nor a collection of essays by a reputable scientist. Nor is it, for that matter, a string of straightforward dispatches from a “science reporter.” It is the work of an outsider who is broadly curious but who can never remember the difference between meiosis and mitosis, who has nevertheless been invited to write on scientific subjects by a small number of charming but gullible magazine editors, who tries hard to keep the facts straight, who is not shy about offering opinions, and whose purpose in these pieces has been divided about equally between edification and vaudeville.

  In the course of pondering what to say in this introduction, I invented an old saying that goes: “Put a magazine writer between hard covers, and immediately he thinks he’s an essayist.”

  Of course I’m no exception. In defense of that claim, I can say only that 1) the first section of this book, “All God’s Vermin,” was taking form in my head as a sequence of essays long before I began making my living from magazine work, and 2) I have tried to shape nearly all of these pieces as essays more than as features or profiles or articles, because old magazines go to the recycling center, whereas old books of essays are allowed to turn yellow with dignity on the shelf. (This doesn’t apply to the piece called “The Excavation of Jack Horner,” which is clearly a profile, commissioned by Esquire as such.) But please don’t ask me to define “essay,” because the atmosphere could quickly grow ponderous. Um, it’s a filigreed editorial whose author doesn’t know just which side he has argued until he reads the rough typescript. It’s a small wobbly verbal dirt bike used for exploring the intellectual backcountry, modest in horsepower yet under imperfect control of the cyclist. See what I mean about the atmosphere?

  During the same time span from which these pieces come, I also wrote others that were definitely not essays—they were profiles or articles or reviews. Them you are being spared. The recycling center has swallowed them already.

  More important than categorizing the pieces of this book, though, is saying what unites them: subject matter and point of view. The subject matter is nature and the nature of science, with excursions into freshwater biology, geology, entomology, theoretical ecology, the history of astronomy, preservation issues, the role of bats in literature. The point of view is generally oblique and (or so I flatter myself) counterintuitive. My ambition has been to offer some small moments of constructive disorientation in the way nature is seen and thought about. Along the way I have been drawn in particular toward certain creatures that are conventionally judged repulsive, certain places that are conventionally judged desolate, certain humans and ideas that are conventionally judged crazy.

  I have also found more fascination in the questions than in the answers. And here’s a further question. On what grounds might we assume or hope that—despite the awesome puissance of modern science—any fertile mysteries still abide, unsolved, in the natural world? I can think of 300,000 reasons.

  ALL GOD’S VERMIN

  Sympathy for the Devil

  UNDENIABLY THEY HAVE A LOT TO ANSWER FOR: malaria, yellow fever, dengue, encephalitis, and the ominous tiny whine that begins homing around your ear just after you’ve gotten comfortable in the sleeping bag. All these griefs and others are the handiwork of that perfidious family of biting flies known as the Culicidae—the mosquitoes. They assist in the murder of millions of humans each year, carry ghastly illness to millions more, and drive not a few of the rest of us temporarily insane. They are out for blood.

  Mosquitoes have been around for 50 million years, which has given them time to figure all the angles. Judged either by sheer numbers or by the scope of their worldwide distribution or by their resistance to enemies and natural catastrophe, they are one of the great success stories on the planet. They come in 2,700 different species. They inhabit almost every land surface, from Arctic tundra to downtown London to equatorial Brazil, from the Sahara to the Himalayas, though best of all they like tropical rainforests, where three quarters of their species reside. M
osquitoes and rain-forests, in fact, go together like gigolos and bridge tournaments, pickpockets and camel markets, insurance salesmen and…But wait, I was talking about insects.

  They hatch and grow to maturity in water, any entrapment of quiet water, however transient or funky. A soggy latrine, for instance, suits them fine. The still edge of a crystalline stream is fine. In the flooded footprint of an elephant, you might find a hundred larval mosquitoes. At that stage of life, as inoffensive juveniles, they use facial bristles resembling cranberry rakes to comb such waters for planktonic food; but on attaining adulthood, they are out for blood.

  Blood: It isn’t a necessity for individual survival, just a dietary prerequisite of motherhood. Male mosquitoes do not even bite. A guy mosquito lives his short, gentle adult life content, like a swallowtail butterfly, to sip nectar from flowers. As with black widow spiders and mantids, it is only the female that is fearsome. Make of that what larger lessons you dare.

  She relies on the blood of vertebrates—mainly warm-blooded ones but also sometimes reptiles and frogs—to finance, metabolically, the development of her eggs.

  A female mosquito in a full lifetime will lay about ten separate batches of eggs, roughly 200 in a batch. That’s a large order of ovular mass to be manufactured in one wispy body, and to manage it the female needs a rich source of protein; the sugary juice of flowers will deliver quick energy to wing muscles, but it won’t help her build 2,000 new bodies. So she has evolved a hypodermic proboscis and learned how to steal protein in one of its richest forms, hemoglobin. Among some mosquito species, the female’s first brood will develop before she has tasted blood, but after that she too must have a bellyful for each set of eggs coming to term.

  When she drinks, she drinks deeply: The average blood meal amounts to two and a half times the original weight of the insect. Picture Audrey Hepburn sitting down to a steak dinner, getting up from the table weighing 350 pounds, and then flying away. In the Canadian Arctic, where species of the genus Aedes emerge in savage, sky-darkening swarms like nothing seen even in the Amazon and work under pressure of time because of the short summer season, an unprotected human could be bitten 9,000 times per minute. At that rate, a large man would lose half his total blood in two hours. Arctic hares and reindeer move to higher ground or die. And sometimes solid mats of Aedes will continue sucking the cool blood from a carcass.

  Evidently the female tracks her way to a blood donor by flying upwind toward a source of warmer air, or toward air that is both warm and moist or that contains an excess of carbon dioxide, or a combination of all three. The experts aren’t sure. Perspiration, involving both higher skin temperature and released moisture, is one good way to attract her attention. In certain villages of Italy there was a folkish belief that to sleep with a pig in the bedroom was to protect oneself from malaria, presumably because the pig, operating at a higher body temperature, would be preferred by mosquitoes. And at the turn of the twentieth century, Professor Giovanni Grassi, then Italy’s foremost zoologist, pointed out that garrulous people seemed to be bitten more than those who kept their mouths shut. The experts aren’t sure, but the Italians are full of ideas.

  Guided by CO2 or idle chatter or distaste for pork or whatever, a female mosquito lands on the earlobe of a human, drives her proboscis (actually a thin bundle of tools that includes two tubular stylets for carrying fluid and four serrated ones for cutting) through the skin, and gropes with it until she taps a capillary, and then an elaborate interaction begins. Her saliva flows down one tube into the wound, retarding coagulation of the spilled blood and provoking an allergic reaction that will later be symptomized by itching. A suction pump in her head draws blood up the other tube, a valve closes, another pump pulls the blood back into her gut. And that alternate pumping and valving continues quickly for three orgiastic minutes, until her abdomen is stretched full like a great bloody balloon or a fast human hand ends her maternal career, whichever comes first.

  But in the meantime, if she is an individual of the species Anopheles gambiae in Gabon, the protozoa that cause malaria may be streaming into the wound with her saliva, heading immediately off to set up bivouac in the human’s liver. Or if she is Aedes aegypti in Peru, she may be drooling out an advance phalanx of the yellow fever virus. If she is Culex pipiens in Malaysia, long tiny larvae of filarial worms may be squirting from her snout like a stage magician’s spring-work snakes, dispersing to breed in the unfortunate person’s lymph nodes and eventually clog them, causing elephantiasis.

  No wonder, then, that in the inverted rogue’s pantheon of those select creatures not only noxious in their essential character but furthermore lacking any imaginable forgiving graces, the Culicidae are generally ranked below even the deer tick, the lake leech, the botfly, the wolverine, and the black toy poodle. The mosquito, says common bias—and on this the experts tend to agree—is an unmitigated and irredeemable pest.

  But I don’t see it that way. To begin with, the Culicidae family is not monolithic, and it does have—even from the human perspective—its beneficent representatives. In northern Canada, for instance, Aedes nigripes is an important pollinator of arctic orchids. In Ethiopia, Toxorhynchites brevipalpis as a larva preys voraciously on the larvae of other mosquitoes, malaria carriers, and then metamorphoses into a lovely, huge, iridescent adult that, male or female, drinks only plant juices and would not dream of biting a human.

  But even discounting these innocent aberrations, and judging it only by its most notorious infamies, the mosquito is taking a bad rap. It has been victimized, I submit to you, by a strong case of anthropocentric bias. In fact, the little sucker can be viewed, with only a small bit of squinting, as one of the great ecological heroes of planet Earth. If you consider rainforest preservation.

  The chief point of blame, with mosquitoes, happens also to be the chief point of merit: They make tropical rainforests, for humans, virtually uninhabitable.

  Tropical rainforest constitutes by far the world’s richest and most complex category of terrestrial ecosystem, a boggling entanglement of life-forms and habits and physical conditions and relationships. Those equatorial forests—mainly confined to the Amazon, the Congo basin and its neighboring Central African drainages, the wetter and warmer parts of Indonesia and northern Australia, and parts of mainland Southeast Asia—account for only a small fraction of Earth’s surface but serve as home for an inordinate share of our planet’s total plant and animal species, including about 2,000 kinds of mosquito. But rainforests lately—in case you’ve been stuck in an elevator for twenty years and haven’t heard—are under siege.

  They are being clear-cut for cattle ranching, nibbled away for subsistence agriculture, mowed down with bulldozers and pulped for paper, hacked and dried for firewood, milled into chopsticks and cheap plywood, gobbled up hourly for the sake of “development” in all its ambivalent forms. The current rate of loss, by one rough estimate, amounts to eight acres of rainforest gone, poof, since you began reading this sentence. Within a few generations, at that pace, the Amazon will look like New Jersey. Conservation groups are raising a clamor, tossing money at the problem, and making efforts to offer mitigating alternatives, while some governments in the countries at issue take steps for marginal preservation in the form of reserves or national parks. But no one and no thing has done more to delay this catastrophe, over the past 10,000 years, than the mosquito.

  The great episode of ecological disequilibrium that we call human history began, so the fossils tell us, in equatorial Africa. Then quickly the focus of intensity shifted elsewhere. What deterred mankind, at least to a large degree, for a very long time, from hacking space for our farms and cities out of the tropical forests? Yellow fever did, and malaria, dengue, filariasis, o-nyong-nyong fever.

  Clear the vegetation from the brink of a jungle waterhole, move in with tents and cattle and Jeeps, and Anopheles gambiae, not normally native there, will arrive within a month, bringing malaria. Cut the tall timber from five acres of rainforest, and
species of viral-transmitting Aedes—which would otherwise live out their lives in the high forest canopy, passing yellow fever between monkeys—will fall on you and begin biting before your chainsaw has cooled. Nurturing not only more species of snake and bird than anywhere else on Earth, but also more forms of disease-causing microbe and more mosquitoes to carry them, tropical forests are elaborately booby-trapped against disruption.

  The resident forest peoples, living at low densities, gradually acquired some immunity to these diseases, and their hunting-and-gathering economies, grounded in relatively simple technology, minimized their exposure to mosquitoes that favored the canopy or disturbed landscape. Meanwhile the occasional white interlopers, the agents of empire, remained vulnerable. West Africa in high colonial days became known as “the white man’s grave.”

  So as Europe was being stripped of its virgin woods, and India and China, and the North American heartland, the tropical rainforests largely escaped, lasting into the late twentieth century—with some chance, at least, that they may endure a bit longer. Thanks to what? To a concatenation of accidental and deterministic factors, no doubt, among which should be included this: 10 million generations of jungle-loving, disease-bearing, bloodsucking mosquitoes—the Culicidae, nature’s Vietcong.

  Has Success Spoiled the Crow?

  ANY PERSON WITH NO STEADY JOB and no children naturally finds time for a sizable amount of utterly idle speculation. For instance, me: I’ve developed a theory about crows. It goes like this.

  Crows are bored. They suffer from being too intelligent for their station in life. Respectable evolutionary success is simply not, for these brainy and complex birds, enough. They are dissatisfied with the narrow goals and horizons of that tired old Darwinian struggle. On the lookout for a new challenge. See them there, lined up conspiratorially along a fence rail or a high wire, shoulder to shoulder, alert, self-contained, missing nothing. Feeling discreetly thwarted. Waiting, like an ambitious understudy, for their break. Dolphins and whales and chimpanzees get all the fawning publicity, great fuss made over their near-human intelligence. But don’t be fooled. Crows are not stupid. Far from it. They are merely underachievers. They are bored.