Small Wonder (10 page)

I
n the slender shoulders of the myrtle tree outside my kitchen window, a hummingbird built her nest. It was in April, the sexiest month, season of bud-burst and courtship displays, though I was at the sink washing breakfast dishes and missing the party, or so you might think. Then my eye caught a flicker of motion outside, and there she was, hovering uncertainly. She held in the tip of her beak a wisp of wadded spiderweb so tiny I wasn't even sure it was there,
until she carefully smoodged it onto the branch. She vanished then, but in less than a minute she was back with another tiny white tuft that she stuck on top of the first. For more than an hour she returned again and again, increasingly confident of her mission, building up by infinitesimal degrees a whitish lump on the branch—and leaving me plumb in awe of the supply of spider-webbing on the face of the land.

I stayed at my post, washing everything I could find, while my friend did her own housework out there. When the lump had grown big enough—when some genetic trigger in her small brain said, “Now, that will do”—she stopped gathering and sat down on her little tuffet, waggling her wings and tiny rounded under-belly to shape the blob into a cup that would easily have fit inside my cupped hand. Then she hovered up to inspect it from this side and that, settled and waddled with greater fervor, hovered and appraised some more, and dashed off again. She began now to return with fine filaments of shredded bark, which she wove into the webbing along with some dry leaflets and a slap-dab or two of lichen pressed onto the outside for curb appeal. When she had made of all this a perfect, symmetrical cup, she did the most surprising thing of all: She sat on it, stretched herself forward, extended the unbelievable length of her tongue, and
licked
her new nest in a long upward stroke from bottom to rim. Then she rotated herself a minute degree, leaned forward, and licked again. I watched her go all the way around, licking the entire nest in a slow rotation that took ten minutes to complete and ended precisely back at her starting point. Passed down from hummingbird great-grandmothers immemorial, a spectacular genetic map in her mind had instructed her at every step, from snipping out with her beak the first spiderweb tuft to laying down whatever salivary secretion was needed to accrete and finalize her essential creation. Then, suddenly, that was that. Her busy urgency vanished, and she settled in for the long stillness of laying and incubation.

If you had been standing with me at my kitchen sink to witness all this, you would likely have breathed softly, as I did, “My God.” The spectacular perfection of that nest, that tiny tongue, that beak calibrated perfectly to the length of the tubular red flowers from which she sucks nectar and takes away pollen to commit the essential act of copulation for the plant that feeds her—every piece of this thing and all of it, my God. You might be expressing your reverence for the details of a world created in seven days, 4,004 years ago (according to some biblical calculations), by a divine being approximately human in shape. Or you might be revering the details of a world created by a billion years of natural selection acting utterly without fail on every single life-form, one life at a time. For my money the latter is the greatest show on earth, and a church service to end all. I have never understood how anyone could have the slightest trouble blending religious awe with a full comprehension of the workings of life's creation.

Charles Darwin himself was a religious man, blessed with an extraordinary patience for observing nature's details, as well as the longevity and brilliance to put it all together. In his years of studying animate life he noticed four things, which any of us could notice today if we looked hard enough. They are:

1. Every organism produces more seeds or offspring than will actually survive to adulthood.
   
2. There is variation among these seeds or offspring.
   
3. Traits are passed down from one generation to the next.
   
4. In each generation the survivors succeed—that is, they survive—because they possess some advantage over the ones that don't succeed, and
   because
   they survive, they will pass that advantage on to the next generation. Over time, therefore, the incidence of that trait will increase in the population.
   

Bingo: the greatest, simplest, most elegant logical construct ever to dawn across our curiosity about the workings of natural life. It is inarguable, and it explains everything.

Most people have no idea that this, in total, is Darwin's theory of evolution. Furthermore, parents who tell their children not to listen to such talk because “it's just a theory” are ignorant of what that word means. A theory, in science, is a coherent set of principles used to explain and predict a class of phenomena. Thus, gravitational theory explains why objects fall when you drop them, even though it, too, is “just a theory.” Darwin's has proven to be the most robust unifying explanation ever devised in biological science. It's stunning that he could have been so right—scientists of Darwin's time knew absolutely nothing about genetics—but he was. After a century and a half, during which time knowledge expanded boundlessly in genetics, geology, paleontology, and all areas of natural science, his simple logical construct continues to explain and predict perfectly the existence and behavior of every earthly life form we have ever studied. As the unifying principle of natural sciences, it is no more doubted among modern biologists than gravity is questioned by physicists. Nevertheless, in a bizarre recent trend, a number of states have limited or even outright banned the teaching of evolution in high schools, and many textbooks for the whole country, in turn, have wimped out on the subject. As a consequence, an entire generation of students is arriving in college unprepared to comprehend or pursue good science. Many science teachers I know are nostalgic for at least one aspect of the Cold War days, when
Sputnik
riveted us to the serious business of training our kids to real science, instead of allowing it to be diluted or tossed out to assuage the insecurities of certain ideologues.

We dilute and toss at our peril. Scientific illiteracy in our population is leaving too many of us unprepared to discuss or understand much of the damage we are wreaking on our atmosphere, our habitat, and even the food that enters our mouths. Friends of
mine who opted in school for English lit instead of microbiology (an option I myself could easily have taken) sometimes come to me and ask, “In two hundred words or less, can you explain to me why I should be nervous about genetic engineering?” I tell them, “Sit down, I'll make you a cup of tea, and then get ready for more than two hundred words.”

A sound-bite culture can't discuss science very well. Exactly what we're losing when we reduce biodiversity, the causes and consequences of global warming—these traumas can't be adequately summarized in an evening news wrap-up. Arguments
in favor
of genetically engineered food, in contrast, are dangerously simple: A magazine ad for an agribusiness touts its benevolent plan to “feed the world's hungry with our vitamin-engineered rice!” To which I could add in reply my own snappy motto: “If you thought that first free hit of heroin was a good idea….” But before you can really decide whether or not you agree, you may need the five hundred words above and a few thousand more. If so, then sit down, have a cup of tea, and bear with me. This is important.

At the root of everything, Darwin said, is that wonder of wonders, genetic diversity. You're unlike your sister, a litter of pups is its own small Rainbow Coalition, and every grain of wheat in a field holds inside its germ a slightly separate destiny. You can't see the differences until you cast the seeds on the ground and grow them out, but sure enough, some will grow into taller plants and some shorter, some tougher, some sweeter. In a good year all or most of them will thrive and give you wheat. But in a bad year a spate of high winds may take down the tallest stalks and leave standing at harvest time only, say, the 10 percent of the crop that had a “shortness” gene. And if that wheat comprises your winter's supply of bread, plus the only seed you'll have for next year's crop, then you'll be almighty glad to have that small, short harvest. Genetic diversity, in domestic populations as well as wild ones, is
nature's sole insurance policy. Environments change: Wet years are followed by droughts, lakes dry up, volcanoes rumble, ice ages dawn. It's a big, bad world out there for a little strand of DNA. But a population will persist over time if, deep within the scattered genetics of its ranks, it is literally prepared for anything. When the windy years persist for a decade, the wheat population will be overtaken by a preponderance of shortness, but if the crop maintains its diversity, there will always be recessive aspirations for height hiding in there somewhere, waiting to have their day.

How is the diversity maintained? That old black magic called sex. Every seed has two parents. Plants throw their sex to the wind, to a hummingbird's tongue, to the knees of a bee—in April you are
inhaling
sex, and sneezing—and in the process, each two parents put their scrambled genes into offspring that represent whole new genetic combinations never before seen on Earth. Every new outfit will be ready for
something,
and together—in a large enough population—the whole crowd will be ready for
anything
. Individuals will die, not at random but because of some fatal misfit between what an organism
has
and what's
required
. But the population will live on, moving always in the direction of fitness (however “fitness” is at the moment defined), not because anyone has a master plan but simply because survival carries fitness forward, and death doesn't.

People have railed at this reality, left and right, since the evening when a British ambassador's wife declared to her husband, “Oh dear, let us hope Mr. Darwin isn't right, and if he is, let us hope no one finds out about it!” Fundamentalist Christians seem disturbed by a scenario in which individual will is so irrelevant. They might be surprised to learn that Stalin tried to ban the study of genetics and evolution in Soviet universities for the opposite reason, attacking the idea of natural selection—which acts only at the level of the individual—for being anti-Communist. Through it all, the little engines of evolution have kept on turning
as they have done for millennia, delivering us here and passing on, untouched by politics or what anybody thinks.

 

Nikolai Vavilov was an astounding man of science, and probably the greatest plant explorer who has ever lived. He spoke seven languages and could recite books by Pushkin from memory. In his travels through sixty-four countries between 1916 and 1940, he saw more crop diversity than anyone had known existed, and founded the world's largest seed collection.

As he combed continents looking for primitive crop varieties, Vavilov noticed a pattern: Genetic variation was not evenly distributed. In a small region of Ethiopia he found hundreds of kinds of ancient wheat known only to that place. A single New World plateau is astonishingly rich in corn varieties, while another one is rolling in different kinds of potatoes. Vavilov mapped the distribution of what he found and theorized that the degree of diversity of a crop indicated how long it had been grown in a given region, as farmers saved their seeds through hundreds and thousands of seasons. They also saved more
types
of seed for different benefits; thus popcorn, tortilla corn, roasting corn, and varieties of corn with particular colors and textures were all derived, over centuries, from one original strain. Within each crop type, the generations of selection would also yield a breadth of resistance to all types of pest and weather problems encountered through the years. By looking through his lens of genetics, Vavilov began to pinpoint the places in the world where human agriculture had originated. More modern genetic research has largely borne out his hypothesis that agriculture emerged independently in the places where the most diverse and ancient crop types, known as land races, are to be found: in the Near East, northern China, Mesoamerica, and Ethiopia.

The industrialized world depends entirely on crops and cultivation practices imported from what we now call the Third World (though evidently it was actually First). In an important departure from older traditions, the crops we now grow in the United States are extremely uniform genetically, due to the fact that our agriculture is controlled primarily by a few large agricultural corporations that sell relatively few varieties of seeds. Those who know the seed business are well aware that our shallow gene bank is highly vulnerable; when a crop strain succumbs all at once to a new disease, all across the country (as happened with our corn in 1970), researchers must return to the more diverse original strains for help. So we still rely on the gigantic insurance policy provided by the genetic variability in the land races, which continue to be hand-sown and harvested, year in and year out, by farmers in those mostly poor places from which our crops arose.