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Chapter One
The Fly Who Came in from the Cold
Inside the cage, John and Yoko were going through the mating ritual. John was the more active of the two, vibrating various bits of his anatomy at physically implausible speeds, while Yoko looked on impassively. Peering through the Plexiglas walls, we whispered laddish encouragement, urging John to make his move. When eventually he did, climbing on top of his partner from the rear, the studious silence of the genetics class was interrupted by our loud chorus of orgasmic cheers.
I spent most of that afternoon with two university friends creating daft nicknames for our captive fruit flies and paying little attention to the science. "John and Yoko," "Sid and Nancy," and "Charles and Di" seemed preferable to the dry and prosaic Drosophila melanogaster. Dozens of star-studded couples passed under our impatient adolescent gaze. Sometimes the flies would sit motionless at opposite ends of their enclosure. Bored and frustrated, we would flick at their cages, willing them into doing something worth watching.
It was difficult to take the fruit fly seriously. Like all insects, it had a head, a thorax, an abdomen, and six delicate legs. It also had wings; two of them. But with all this presented in a body less than half the size of a grape seed, here was an animal crying out to be ignored. You could squash a hundred of them without noticing, and I did. On my own, purely subjective, scale of animal aesthetics, the fruit fly ranked pretty low; respectably higher than the flatworm, but some way below the dog whelk.
Even among its evolutionary relatives, the fruit fly hardly seemed to stand out. It lacked the ghoulish charm of distant cousins like screwworm flies, which laid their eggs in the genitals, mouth, and nose of their hapless mammalian victims. It had none of the infectious stealth of disease-mongers like mosquitoes, with their incumbent coterie of parasitic hangers-on. It didn't even have any annoying agricultural habits, unlike the notorious medfly (also known, confusingly, as a "fruit fly"), which grabbed headlines by destroying citrus crops in California and Europe.As far as I was concerned, screwworm flies, mosquitoes, medflies, and the like were the real party animals: flies that evolution had blessed with intrinsically interesting lives. The fruit fly, on the other hand, seemed like an early-to-bed-with- a-cup-of-hot-cocoa sort of fly.
But my feelings about the fly soon changed. After finishing my degree, I went looking for a Ph.D. in evolutionary biology, and was confronted with a baffling choice of projects and organisms. At the time, I was more concerned with the organism than the details of the science. My main priority was to work on a "proper" animal, something brightly colored with fur or feathers living in a remote part of the Amazon. Unfortunately, this seemed to be a priority shared by most of my peers. So, in the end, I had to settle for what I could get'a project on a small species of moth in South Wales.
The project lacked the glamour I had yearned for, but later I realized that this could be a blessing in disguise. Choosing a glamorous Ph.D. could mean a free ticket to the tropics. But more often than not, you would return, three years later, with an empty notebook, a bad dose of malaria, and a scientific career in tatters. Once you had learned the language, established a base camp, and set up your tripod, it was time to come home. You could always pick out these choice victims at academic conferences. They were the ones wearing glazed expressions over their suntans.
But there were others who stood out from the conference crowd: young, self-confident individuals whose demeanor suggested they were going places. These were people for whom public speaking seemed to hold no fears. They gave talks that translated each short scientific life into one long success story. They collected new facts like a bee collected pollen. And they had their work routinely published in the distinguished pages of Nature and Science. They came from all corners of the globe but were united by a common bond. Who were these people?
They were the ones who had chosen to work with fruit flies.
If my brief stint in academia taught me anything, it was that my system of animal aesthetics was completely incompatible with the practical, temporal, and financial constraints of biological research. The animals I'd dismissed as irrelevant'small insects, for example'excelled as research tools. And the animal I'd dismissed as most irrelevant 'the fruit fly' stood head and thorax above all others. The fruit fly came with all the attributes of other small insects. But it also came with something else: a long and distinguished scientific history.
The fly made its official laboratory debut in 1900, under the watchful eye of Harvard University professor William Castle. In all truth, the crossing of the laboratory threshold was very much a nonevent. Castle needed a study organism for one of his embryology students. The fruit fly seemed like a cheap and cheerful option, so a few ripe grapes were left on a windowsill, and any flies that took the bait were brought inside.
The fly was just one of many new experimental animals to be tried and tested during the tail end of the Victorian era, as biology underwent a major revamp. For most of the nineteenth century, biology had been dominated by the naturalist philosophy. Naturalists believed that uncovering biological truths depended on meticulous observations of life in its natural context. As a consequence, biology was characterized by a near obsession with descriptive detail. From a tiny hair on a beetle's bottom to a family of fleas in a kangaroo's crotch, nothing was too trivial to document.
But as the nineteenth century wore on, the naturalists came under increasing attack from a new generation of biologists who viewed life with more materialistic and mechanistic eyes...
