The Canon (38 page)

Indeed, the pharmaceutical industry would love to tap into that genomic flexibility, to design drugs that would go right to the source code in a patient's cells, and fix a problem by fine-tuning gene expression—persuading the liver to make more of the high-density, or "good," form of cholesterol and less of the "bad" low-density lipoprotein, or bone tissue to remodel itself and heal a broken hip, or the brain to supply an optimized cocktail of neurochemicals to conquer depression, despair, a chronic sense of inadequacy, which may or may not be warranted but which is always unpleasant. And why not get rid of the recurrent nightmares, too, like the one in which you're onstage, dressed as the Scarecrow in
The Wizard of Oz,
and you can't remember the line that comes after "I would dance and be merry..."

Oh, for the day when we can have a heart-to-heart with our neurons and tailor our drugs to form-fit our genomes. Oh, to have the wits of a liver, the shrewdness of a single cell. Yes, my friend, life would be a ... ding-a-derry! If we only had the brains.

W
HEN YOU LIVE
in the nation's capital, where every glorious monument to liberty is ringed with Jersey barriers and status is measured by the size not of one's paycheck or limousine but of one's Secret Service detail, you get used to imagining all sorts of disasters. A child's kite looks like a perfectly plausible anthrax distribution device. The van that screeches to a halt at an intersection when the light is still yellow surely houses a dirty bomb. A man dressed in a bulky, ill-fitting Brooks Brothers raincoat looks suspicious. A man
not
dressed in a bulky, ill-fitting Brooks Brothers raincoat looks suspicious.

Yes, in Washington, D.C., and its environs, you learn to think the unthinkable and to prepare for a wide range of emergencies, primarily by stockpiling duct tape, canned soup, and extra cat litter. One thing you almost never worry about, however, is an earthquake. Which is why, when I was working up in my office on a spring afternoon, and I felt the house start to jiggle and sway, I thought about everything other than an earthquake: a terrorist attack, a passing Abrams tank, my neighbor with the big dog and the Vin Diesel line of lawn tools, who runs his leaf blower at night, in the rain, just because, he's kindly explained to me, he can.

But as the shaking continued, I realized I'd felt the exact same sensation once before, when I lived in San Francisco, and that it could only be an earthquake. For nearly half a minute, the house shook, while I stayed stock-still in my chair, safely positioned beneath a large ceiling fan. I tried not to panic. I tried not to think about Carole King singing, "I Feel the Earth. Move. Under My Feet," but it was too late, and now maybe it is for you, too. Sorry! Finally, when I was sure at least the swaying part of the crisis had passed, I called my husband, whose office was in downtown Washington, some six miles away.

"Did you feel that?" I gasped.

"Feel what?"

"Well, you're not going to believe this," I said, "but I'm pretty sure we just had an earthquake."

"On some new medication, are we, dear?"

I muttered an imprecation, or maybe it was an oath, hung up the phone, and basked briefly in the warmth of righteous indignation. A moment later, my husband called back. "You're right," he said. He'd just seen a wire story go by, reporting an earthquake extending from parts of Virginia through to Maryland, where we live, and measuring 4.5 on the Richter scale. Venturing out into the hall, I saw that all the pictures on the wall were askew, and that one of them—a drawing of a woman who, come to think of it, looks a lot like Carole King—was on the verge of crashing to the floor.

The capital is not a seismically flamboyant region. It lacks California's tic-tac-toe of active fault lines, the lava luaus of Hawaii, the captious powder-point volcanoes found in that other place called Washington. Yet every now and again, even a sedate location with no known geological risk factors will give a sharp little shrug and demand that earth scientists pay it some mind. The intermittent jolts and tremors offer unambiguous evidence of a geological principle that truly merits the designation "bedrock": The planet we inhabit, the bedrock base on which we build our lives, is in a profound sense alive as well, animate from end to end and core to skin. Earth, as I said earlier, is often called the Goldilocks planet, where conditions are just right for life and it is neither too hot nor too cold, where atoms are free to form molecules and water droplets to pool into seas. There is something else about Goldilocks, beyond her exacting tastes, that makes her a noteworthy character, a fitting focus for our attentions. The girl cannot sit still. She's restless and impulsive and surprisingly rude. She wanders off into the woods without saying where she's headed or when she'll be home. She barges through doors uninvited, helps herself to everybody else's food, and breaks the furniture. But don't blame her. She can't help herself. Goldilocks is so raw and brilliant that she just has to let off some steam. Like Goldilocks the protagonist, Goldilocks the planet is a born dynamo, and without her constant twitching, humming, and seat bouncing, her intrinsic animation, Earth would not have any oceans, or skies, or buffers against the sun's full electromagnetic fury; and we animate beings, we DNA bearers, would never have picked ourselves up off the
floor. The transaction was not one-sided, though. The restless, heave-hoing motions of the planet helped give rise to life, and restless life, in turn, reshaped Earth.

"We now understand that it isn't simply a matter of life accommodating to the buffets of physical change, but that life is a participant in the evolution of environments," said Andrew Knoll of Harvard University. "A grand theme of the history of our planet is how physical and biological Earth have coevolved through time."

When the whole world is your subject, it pays to be well-rounded, and geologists consider themselves the ultimate interdisciplinarians. They do fieldwork and lab work and crib from chemistry, physics, ecology, microbiology, botany, paleontology, complexity theory, mechanics, and, of course, computer modeling; geologists compete with protein chemists for their production of colorful computer-generated schematics that can be manipulated multifactorially in three-dimensional space and also make very nice screen savers. They love being outdoors, chipping away at rocks, leaping blithely from one sheer precipice to the next, and slowly acquiring the complexion of a Slim Jim. Geologists are often drawn to regions of great natural beauty and spotty safety records: active volcanoes, active fault lines, mountainous borders between sporadically warring nations. Unnatural eyesores can also have their appeal. When a new tunnel is blasted through a hillside, geologists will descend on the site for a chance to study the vast spans of geohistory that are fleetingly exposed, and if necessary may stall for time by throwing their graduate students in front of any oncoming cement mixers.

For geologists, every stone is a potential Rosetta stone, a key to a milestone moment in Earth's history, and to accompany a geologist through a park is to leave no stone unturned or outcrop unlearned. While strolling in the Arnold Arboretum on an unusually cold summer afternoon, Professor Kip Hodges, then at MIT, stopped at a thigh-high boulder that looked like a big lump of hardened cookie dough, and he took me through its résumé. "This is the kind of rock we commonly refer to as a conglomerate, which is just a rock that has blocks of different materials in it," Hodges said, pointing at the embedded chunks of what looked like nuts, or grayish white chocolate chips. "Notice that in this case you have blocks of many different sizes, and they're surrounded by a lot of fine-grained material, as though the blocks were just dumped and then locked into place." He ran his hand across the surface, and I followed suit. Very knobby, and chilly to the touch. When you see a mix of fine-grained and big material like this, Hodges explained, it's a good bet that the rock is of glacial origin. He took a seat on the boulder, and
I, less eagerly, followed suit. Very,
very
knobby, and most decidedly of glacial origin. The blocks that are now embedded in our exemplary boulder may have been rafted in by a creeping sheet of ice; the ice melted out, and the rocks became incorporated in the underlying sediment. "So the next question," Hodges said, "is when did all this happen?"

He then explained to me the considerable challenge of fixing an age to the boulder, a task that required, among other steps, sampling each embedded blockette for its relative concentration of radioactive tracers like uranium and thorium. But the effort proved exceptionally fruitful. The boulder on which we were perched turned out to be 570 to 590 million years old and just one of many like it discovered at sites around the world. Taken together with related research, the age and distribution of these rocks suggested that there had been a heretofore unknown ice age of great antiquity and scope, a hypothesis that many geologists are now pursuing. All of which demonstrates the geologist's first principle of fieldwork, Hodges said, as he gave the boulder an affectionate pat—that the real gems of the landscape are often the plainest-looking stones. It was a lesson I learned by the seat of my thin cotton pants.

"We live on a planet that records its own history," said Andrew Knoll. "I'm always amazed, when I drive across Utah, that I see this wonderful history unfolding before me, and you don't have to be a scientist to experience it. If you keep your eyes open as you go through the Grand Canyon, you'll see fossils. If you stop at almost any roadcut in the Midwest or look at the floors of almost any cathedral in Europe, you'll see fossils. It was hard to be a medieval penitent on one's knees without running into an ammonite every step of the way."

Yet for all the texts scratched onto its surface, Earth can also be a taciturn mule of a research subject, close to the vest and physically just about impenetrable. The deepest hole ever drilled got 7.6 miles down, a mere two-thousandths of the distance to the planet's searing inner core. Most of what geologists know about the inner earth they have gleaned indirectly. In the laboratory, they heat rocks and squeeze rocks and wring them into stone soup, charting the changes in the rocks' behavior and conductance properties with each new form of abuse. So armed, geologists can make the best of everyone else's bad day. When an earthquake strikes, they observe with the greatest possible precision how the waves of energy ripple outward from the quake's epicenter—their speed and direction, the relative decline of magnitude over distance, any harmonic overlays and reverberations they may have. The researchers can then compare the characteristics of those seismic waves
with what they have learned about the conductance properties of different types of rock in their solid and molten states. Earthquakes, in other words, are like sonograms, the waveforms of seismic energy offfering a portal into the imperial organs below.

Geologists sometimes complain that we have devoted more time and effort to exploring other planets than we have to our own, and they've been driven to propose extreme remedies for the knowledge gap. David Stevenson of Caltech, for example, has suggested that we make a slender crack right down to the earth's midpoint and then send in probes to sample the core directly, an idea he published in the scientific journal
Nature
under the Swiftian title "A Modest Proposal."

"I was being somewhat tongue-in-cheek, but I wanted people to realize that the idea may not be completely ridiculous," he said to me. "Making the crack in the first place could be difficult, but once you got it started, it would propagate under the effect of gravity."

Whatever technical limitations they may chafe under, geologists have come a long way since Jules Verne imagined the center of the earth as a kind of daffy reliquarium filled with mastodons, icthyosaurs, plesiosaurs, "Ape Gigans," and other members of nature's backlist. They've made their way around to something like the fifteenth-century fantasies of the good fire-breathing friar Savonarola.

We're all familiar with the idea that the earth's surface is broken into pieces, or tectonic plates, and that the movements of these plates has something to do with earthquakes, volcanic eruptions, and the pumice stone now gathering fungal spores in the corner of your shower stall. A simple glance at a desktop globe reveals that the plates have been slumming about for some time: South America and Africa look like matched pieces of a jigsaw puzzle that once fit together but have since been scattered across the floor, just like what happened when you didn't put away the 1,000-piece puzzle of the signing of the Declaration of Independence, and now John Hancock's quill and John Adams's right thigh are gone forever. What is less widely known is the reason for these chronic continental perambulations, these bumps and rasps of plate against plate. At which point, I must say it's a shame that respectable Christian theologians dispensed long ago with the idea of hell as a specific, corporeal, very hot and nasty place located deep underground and have replaced it with a flaccid metaphor along the lines of "hell is the spiritual desert in which one dwells if one turns away from God." As it happens, there
is
a raging inferno buried some 1,800 miles underground, an authentic hell in Earth, and it is none other than our planet's core. This pyred pit, this devils' spa and nail salon, is a ball of
blazing metal roughly the size of Mars, 90 percent iron and the rest mostly nickel, and it burns at a temperature of 10,000 degrees Fahrenheit, nearly as hot as the surface of the sun. The core has been seething continuously since Earth coalesced, and with almost unmitigated brimstone, cooling by only 300 degrees over the past 4 billion years. Most of that heat is left over from the cauldron conditions of the early solar system, and from the inevitable transformation of potential energy into thermal energy that comes when gravity pulls a lot of scattered matter into a compact planetary ball. The rest is supplied by rich stores of unstable radioactive elements like uranium, thorium, and potassium, which in decaying release energy into their milieu, their terrestrial stew, and so keep stirring the pot. Earth is exceptionally blessed with radioactive material, and the feverish click, click, clickings of decomposing heavy atoms, along with the core's primal heat, explain why our planet is such a changeling, displaying more geologic verve and greater turnover of its dermal layer, its surface anatomy, than all the other planets of the solar system combined. Mars used to have a similar geologic profile, a blistering core driving large-scale upheaval—crackling crust, volcanoes spewing ash and gas. But Mars, being significantly smaller than Earth, had far less internalized heat and fissionable goods to begin with, and its furnace went cold a billion years ago, leaving the planet a relatively indolent world, its worn, pitted face pretty much set in its ways. The Earth, by contrast, is a mad master of plastic surgery, recurrent patient and outré doctor bundled as one. Do you think India looks good down here, cheek by jowl with Madagascar? No? Then how about sutured to China? And Australia: Better down here, blended together with Antarctica, or as a standalone flower of the Indian Ocean? Or maybe you'd prefer if we slid it northward and into Japan?