The Illustrated Insectopedia - Hugh Raffles (2010)

Heads and How to Use Them

1.

I missed the crickets. I missed their friends. I opened The New York Times and missed them even more.

Flies, fruit flies, Drosophila melanogaster, the experimental animal par excellence, arguably more important even than rats or mice in the history of modern science. These haunting video stills were shot in 2006 in a neuroscience lab in southern California. The flies are fighting, and the U.S. government—channeling its money through the National Science Foundation—is betting on the winners.1 The arena is a telegenic blue.

Herman A. Dierick and Ralph J. Greenspan, lead researchers at the Neurosciences Institute in San Diego, are breeding fruit flies for aggression. Flies, they tell Nicholas Wade of the Times, are militantly territorial in the wild but lose their edge in captivity. Professors Dierick and Greenspan fill pots with fly food and encourage individual males to defend them. They call this the “arena assay.” They rank the flies on an “aggression profile” based on four criteria: the frequency of fighting, the rapidity with which the animals engage, the amount of time a pair spends in combat, and the fervor of the battle (“the number of high-intensity elements such as holding or tossing”).

Dierick, Greenspan, and their colleagues separate the most belligerent fighters to use as breeding stock. After twenty-one generations, they report aggression-profile differences of more than thirtyfold compared with their control population of standard laboratory flies. “Because aggression levels are likely to be strongly influenced by the brain,” they decapitate generation 21. They grind the heads. They want to know if genes expressed in the fighters’ brains can be correlated with the newly aggressive behavior. “Dr. Greenspan said an understanding of how genes set up circuits to govern behavior would be of broad significance in understanding what makes either flies or people tick,” writes Wade.2

2.

Fruit flies are well suited to the experimental life. Perhaps too well. They breed fast (in ten days, a female can complete her reproductive cycle and produce 400 or even 1,000 offspring). They have a relatively simple genetic structure (only four to seven chromosomes). And like every other organism, they mutate.

In 1910, the Columbia University geneticist Thomas Hunt Morgan stumbled on the capacity of Drosophila to produce startlingly visible mutations—and to produce them in quantity. Almost at once, fruit flies were no longer just minor annoyances that breezed in through the open summer windows in upper Manhattan, nosed around, and stayed or left. They were “fellow laborers,” as their biographer Robert Kohler puts it.3 Morgan’s lab soon became their lab (the internationally famous Fly Room), and Morgan and his colleagues soon became their scientists (they called themselves fly people and drosophilists).

Very rapidly, the fruit fly became a fixture of genetics laboratories worldwide. Indeed, writes Kohler, without its capacity to act as “a biological breeder reactor” and produce enormous quantities of mutants, we might still be awaiting the arrival of modern genetics.4

In those early years, as Morgan and his fly people incorporated Drosophila into their experimental work, they found themselves struggling to keep up with its prodigious ability to produce mutations. They were overwhelmed by, swamped by, mutants. Such a quantity of new data demanded a new experimental method, one characterized by high-volume efficiency, and mass gene mapping rapidly took shape as the new signature of genetic research. In turn, the constraints of the new method demanded a new fly, a consistent fly that could be compared to other flies with confidence. It required an animal free of the high natural variability of the nonlaboratory population, an animal in which all observed variation would be unmistakably a product of experimental mutation, “The little fly,” writes Kohler, was “redesigned and reconstructed into a new kind of laboratory instrument, a living analogue of microscopes, galvanometers, or analytical reagents.”5

A fly was born. A novel animal, so long as it could be prevented from combining with its nonstandard relatives. The researchers sought parental material in the most desirable mutants, the ones that were robust, keen to mate, fecund, and easily distinguishable from those other Drosophila buzzing busily beyond the Fly Room. These were also, Morgan noted, the ones that were “free from such bad habits as getting drowned, or stuck in the food, or refusing to be emptied from the culture bottle, etc., which alienate the affections of the experimenter.”6

The new fly was cooperative, amenable to experiment, attuned to the production of precise, numerical data. Unlike its increasingly distant cousins outside the lab, who took to the air only at dawn and dusk, it was active all day long and bred around the clock. It was mass-produced to produce experiments in mass. By the best estimates, in creating the genetic map of the standard fly between 1919 and 1923, Morgan and his colleagues “etherized, examined, sorted, and processed” between 13 million and 20 million of them.7 And in the midst of such attention to numbers, the enormous imprecision of that figure says as much about the animal’s status as does the enormous figure itself.

You might argue that by entering the laboratory, the fruit fly guaranteed itself a life of ease and plenty. No more foraging for food or dodging predators, no more vulnerable larvae. Up to that moment, along with dogs, rats, cockroaches, and a few other household familiars, the fly had been an opportunist, a companion animal sharing human history, finding a home alongside and among us, neither fully wild nor truly domesticated (commensal might be a good term), eating where we ate, thriving where we thrived, and no doubt surviving where we failed.

But laboratory life isn’t much of a bargain. Countless billions of Drosophila have been subjected to induced mutations since Morgan’s day. As Cornelia Hesse-Honegger witnessed, they grow too many body parts—or too few—and they grow them in the wrong shapes and in the wrong places (legs from their eyes, legs from their legs—you know how it goes). With a little help, they develop Huntington’s, Parkinson’s, and Alzheimer’s diseases. They experience sleep and memory disorders. They get addicted to ethanol, nicotine, and cocaine. In short, as Cornelia realized, they not only bear the burden of our dreams of health and longevity, but they also assume the task of living out our nightmares.

3.

As the industrial fruit fly became more standardized, as it changed and grew apart from its unfettered cousins, and as—at the same time—it became more and more a product of the Columbia Fly Room, Morgan and the drosophilists came increasingly to admire and respect it, to regard it, as did the geneticist J.B.S. Haldane, as a “noble animal.” Considering how much of themselves they’d put into creating it, how much time they were spending in its company, and how closely it was collaborating in their work, it isn’t surprising that they personified the fly. But still, this intimate bundling of admiration and slaughter is telling and a little strange too, until one thinks of the ways in which nobility is often twinned with sacrifice and how all of them—flies and fly people—had embarked on a great voyage, the kind of scientific voyage of discovery that often includes suffering and self-sacrifice as integral components of its narrative.8

Maybe the limits of this little strangeness can help us understand a bigger strangeness too: how this fly can be so like us that it seems natural to think of it as our biological surrogate and simultaneously can be so entirely unlike us that it seems equally natural to subject it, without remorse or even concern, to unconstrained destruction.9

Those images of the fighters are disconcerting. So far from Shanghai, so unexpected, flies not crickets, such a blunt instrument, thrust into a culture of no culture, caught on video, losing their heads. In Shanghai, the lines are clear: there’s ambiguity and attachment but no confusion. In San Diego, too, the lines are drawn, and there’s also no confusion. But there’s no ambiguity either. In San Diego, similarity is quantifiable. Even if the numbers aren’t entirely solid yet, the facts still count: humans and fruit flies share many of the same genes; we share metabolic and signaling pathways at the cellular level, and, many neuroscientists are willing to argue, we overlap substantially in behavior and (what the scientists contend are) its molecular mechanisms.10

There are few niceties here. Animal experiments are blunt instruments, and the logic of the model organism is to separate body and soul, biology and consciousness, physics and metaphysics. It’s easy when similarity and difference are not ranged on the same scale, when the basis for judging one is not the same as that for judging the other, when the criteria of similarity are genetic and the criteria of difference do not even require articulating: they are ancient, Aristotelian, now commonsensical, obvious, tedious to enumerate. Let’s say only that these are insects, that their difference—and what it allows—is not in question. Elias Canetti understood this. Insects, he wrote, “are outlaws”:

The destruction of these tiny creatures is the only act of violence which remains unpunished even within us. Their blood does not stain our hands, for it does not remind us of our own. We never look into their glazing eyes.… They have never—at least not amongst us in the West—had the benefit of our growing, if not very effective, concern for life.11

Annemarie Mol, the Dutch philosopher and anthropologist, has studied the social life of atherosclerosis, a disease that narrows the arteries and inhibits circulation, first in the legs and eventually in the heart. Mol is an acute observer. She attends autopsies on atherosclerosis patients, many of whom died under hospital care. She notices that as the pathologists slice through the heavy flesh to enter the circulatory system, they often take a moment to cover the corpse’s face with a piece of cloth.12 Mol considers this gesture and concludes that there are in fact two corpses—one body but two beings. One being, the body being sliced, is the biological body, the scientific body, freed of the metaphysics of humanity and free to be dissected as a piece of meat, anonymous. The second being, the body being sliced, is the social body, a body with history, family, and friends, a body that has loved and suffered and demands modesty, respect, and attention. Mol’s point is not to choose which of these bodies is lying on the autopsy table but to show that both bodies are present and that the simple gesture with the cloth—the covering of the face—is also a simple gesture of recognition.

Maybe for now that cloth can also mark the difference between the fighting crickets of Shanghai and the fighting flies of San Diego. Maybe the difference is ontological. In Shanghai, each cricket is many crickets, many beings with many histories and many friends are compressed into its limber frame. Around it, many dreams unfold, many projects rise and fall. If they are warriors, so are we. In San Diego, there is only the scientific fly, “an instrument, a living analogue of microscopes, galvanometers, [and] analytical reagents” whose purpose is clear, whose role is defined, whose death is not at issue, whose life is not at stake.