The Universe Within: Discovering the Common History of Rocks, Planets, and People

by Neil Shubin

  Paul Tudge discerned tiny stumps in a vast landscape, paleontologists find tiny fossils inside a field of rocks, and our primate ancestors survived climate change by discriminating nutritious foods in a dense collage of leaves in forests. Every time you admire a richly colorful view, you can thank India for slamming into Asia, continents for retreating from Antarctica, and the poles for becoming frozen wastes. Buried within it all lies the way carbon atoms move through our world.

  CHAPTER NINE

  COLD FACTS

  As we lumbered along at a ground speed of thirty miles per hour, I felt as if our plane would drop from the sky. With this strong headwind, the five-hundred-mile trip from Iceland’s capital, Reykjavík, to our remote landing strip on east Greenland could take nearly half the day. The craft we were flying, a DeHavilland Twin Otter, is the workhorse of the Arctic. With a stall speed of fifty-five miles per hour and fitted with huge balloon tires or skis, it can land on tiny patches of rocky tundra or ice nestled in remote Arctic valleys. Hunched in a compartment big enough for only four crew, pilots, and gear, I could only imagine how early Arctic explorers—those who set out in the nineteenth century with wool coats, leather shoes, and salt pork dinners—felt on their first sight of the North. With the slow ride and a window seat, I was able to linger on the view.

  During the trip north, the vista transforms as plants recede and the extent of ice expands. The sea ice appears in patches at first, then forms a solid sheet over the ocean. Seen from ten thousand feet, the ice grades from a clean, almost pure white to shades of blue, green, and teal. With shapes like no other place on Earth, it fractures in cubes in some spots and in long sticks and crystalline diamonds in others.

  The slow, low-altitude approach to Greenland is defined by an ominous wall of fog that lingers in the windshield for hours. As one gets closer, the fog is revealed to be a massive sheet of ice that extends as far as the eye can see. The center of the island is filled by one of the largest glaciers on the planet. The sheet extends six thousand feet high and six miles deep, over an area the size of Texas. Exposures of bedrock of the island are restricted to cliffs that line the coast; the rest of Greenland’s rock lies buried deep under ice. The ice cap is a lifeless glacial desert touched by humans only rarely.

  In one bout of activity, this desert of ice sprang to life in the 1950s, when Greenland took strategic importance during the Cold War. On the northwest corner of the ice cap a secret project run by the U.S. Army was launched with a name right out of Dr. Strangelove: Project Iceworm.

  The plan, concocted somewhere in the seventeen miles of Pentagon hallways, was to carve silos for six hundred nuclear warheads in the ice in northern Greenland. Connecting these silos were to be tunnels that contained an entire underground city given the futuristic name Camp Century.

  The project was started secretly in 1959, when twenty-one tunnels were dug with heavy equipment flown from bases far to the south. In its heyday, this city under the ice housed over two hundred people and contained a shop, hospital, theater, even a church. Power was supplied by the world’s first portable nuclear reactor, the plucky Alco PM-2A. Heat from the reactor melted ice to provide the subglacial city with water. Self-sufficient and mostly belowground, the whole operation was something like a human ant farm.

  In its heyday, “Main Street” of Camp Century was eleven hundred feet long. The area was crushed by ice by 1969. (Illustration Credit 9.1)

  Being close to perceived threats in the U.S.S.R., Camp Century had the makings of a perfect military base. The plan worked well, except for one problem: ice moves. By 1966, it had become clear that the ice was shifting so extensively that warping tunnels would destroy expensive equipment. Pictures of Camp Century taken today reveal twisted machinery and abandoned huts, all artifacts of schemes and fears inside an ancient block of ice.

  Work at Camp Century did have value, though not of the type Pentagon planners could have ever foreseen.

  A SUMMER VACATION THAT CHANGED THE WORLD

  Louis Agassiz was born in 1807 with charm, intelligence, and an unrelenting passion to study nature. Even as a child, he fed his insatiable curiosity by making his own collections of animals and plants, often drawing each of their organs in exquisite detail. He believed in learning by seeing, a dictum that was to become his catchphrase throughout his career. Sensing his proclivities at an early age, his parents set him up to apprentice with an uncle who had established a successful business. They wanted Louis to develop into a successful “man of affairs,” not a collector of bugs and rocks. But they underestimated the influence of his charm. Young Agassiz would have none of his parents’ designs: he enlisted one of his teachers to lobby his parents for him to stay in school and become, as he said later, “a man of letters.”

  While Louis was in his late teens, he and his brother were studying in Zurich and found themselves without a ride home, a distance of over a hundred miles. They started walking until a stranger, a well-to-do Swiss, offered them a lift. So impressed was he with Agassiz’s acumen that this gentleman later wrote to his parents offering to pay for his full education. Thus began a steep career trajectory that ultimately propelled him to the United States, where he took part in the founding of two major scientific centers: the Museum of Comparative Zoology at Harvard and the National Academy of Sciences.

  As a young family man in 1837, Agassiz took his brood on a summer vacation to the picturesque town of Bex. Lying along the Rhône River, Bex is bordered on the east and west by the Alps. Today it is home to the only working salt mine in all of Switzerland. A narrow-gauge train takes visitors hundreds of feet beneath the earth. This vast hole was originally dug in the 1820s to quarry salt that in those days was literally worth its weight in gold. At the time of Agassiz’s visit the mine was new, and its director took great pleasure in showing summer visitors the local geology, which in this part of the Alps is hard to miss and very easy to appreciate.

  Louis Agassiz. (Illustration Credit 9.2)

  Some time before Agassiz’s visit, the director and a friend had discovered a number of puzzles in the local rocks. With the arrival of Agassiz, the two were excited to quiz a visiting luminary on the meaning of these geological oddities.

  Giant boulders dotted the landscape, some the size of a caravan. That is not unusual; large boulders can be a common occurrence. But these were completely out of place, because the rock that composed the boulders was different from the local bedrock. In fact, the closest match to the boulders was in cliffs hundreds of miles away. Something had transported them, but what?

  Closer inspection of the boulders revealed other clues. Scrape marks, almost as if made by a pickax, etched their surfaces. And the marks didn’t run willy-nilly; they extended in parallel lines.

  More mysteries came from a bird’s-eye view of the valleys from the scenic overlooks that lie along the roadsides of this part of the Alps. Each of the mountainous valleys was bordered by ridges of gravel that looked scrunched, almost as if they had been moved by a plow or a steam engine. Since the ridges were perched on hillsides in rural valleys, these causes were obviously ruled out.

  Boulders and gravel mounds told the same story: something was moving rocks around. But what?

  Flowing water could be ruled out. Floods large enough to move the giant boulders would have left very obvious markings across the landscape. Of course, human activity could be ruled out as well. That left the one obvious cause—ice.

  At the time of Agassiz’s visit, the ice was nestled in glaciers high up on the mountains. But what if that was only its most recent position? What if at some point in the past the ice covered the valleys below? If the levels of ice waxed and waned in and out of the valleys, then the boulders would move, and the rubble would be plowed about to make mounds and carve scrapes.

  After this grand show-and-tell, Agassiz’s friends tried the ice idea out on him. To Agassiz—whose life’s modus operandi was to learn by observing—the visit sparked an epiphany. It was a set of observations that chan
ged his world. At every scale, Switzerland’s rocks made sense when considered in the light of moving ice: scrapes on rocks told the same story as the mounds of gravel and the shapes of the valleys themselves. Agassiz’s heart raced at the thought of something even more general. His travels revealed these features weren’t limited to the Alps; they were common all over Europe, even south to the Mediterranean. Moving ice wasn’t confined to picturesque Swiss cantons; it must have covered virtually all of Europe.

  Unbeknownst to his friends in Bex, Agassiz set off to test his grand idea. In 1840, he published a book, dedicated to his friends from that fateful summer vacation, called Studies on Glaciers. In it he proposed the radical notion that ice at one point in time extended from the North Pole all the way to the Mediterranean and then retreated, only to extend again. A friend came up with a catchy name for these cold intervals: “ice ages.”

  Agassiz, with his personal charm, set off to convince the great eminences of the time of his notion. He took visitors out in the field as his friends from the summer vacation had done for him, encouraging them to see a past rich in ice. It took many trips, and even more arguments, but Agassiz succeeded. The ice age theory became widely accepted.

  The beauty of this theory was that, like most great scientific ideas, it made specific predictions. Agassiz’s notions could be tested simply by looking at the rocks in the world. Exotic boulders, mounds, and linear gashes on rocks should be widespread. If it is one thing to find a widespread pattern, then it is the clincher to find the cause.

  But a problem for enthusiasts was that Agassiz’s ice ages lacked any plausible mechanism. In fact, the idea even flew in the face of existing dogma that Earth has been cooling over time. If Earth was cooling, then glaciers should not have retreated to where they are today; they should have expanded. Moreover, Agassiz’s layers of gravel and boulders were showing not a single shift but a rise and fall of Earth’s temperatures over time. What caused the waxing and waning of the ice?

  DANCING WITH THE STARS

  Born and raised on a farm in Scotland, James Croll (1821–1890) lacked any formal education. Like Agassiz, he lived for the life of the mind: great ideas, puzzles, and intellectual problems. To support himself, he tried selling insurance, but with a natural aversion to people he couldn’t stomach the job. Leaving that, he set up a tea shop. While he still couldn’t manage to avoid people altogether, the shop did offer one salient advantage over the other gig: it left him plenty of time to study. And studying was the one thing he absolutely loved to do.

  Croll’s physiognomy, revealed by the best-known picture of him, shows the thousand-mile stare of one whose mind is transported to a faraway place or working on a deep mathematical problem. His mouth, set firm with a Scottish obduracy, also reveals a decided lack of humor; one can’t imagine many jokes emerged from those lips. By all accounts, Croll had an exceptional focus that, coupled with a passion for learning, would allow him to spend an entire year reading a single book, often lingering on one page for a day or more to digest each idea. His driving passion was to get to the bottom of intellectual problems. Not satisfied with seeing only patterns, he wanted to figure out how the world actually worked.

  James Croll (clearly not thinking about tea). (Illustration Credit 9.3)

  Agassiz’s ice ages provided a puzzle ripe for the solving. Croll’s approach was decidedly different from that of Agassiz before him. Thinking of fundamentals, Croll asked, “What was the cause?” He set off with a pad and pen to solve the problem. His search for a cause demanded thinking about the factors that changed the amount of heat on Earth. The source for much of that heat is the sun. Is there some regular variation in heat from the sun that could trigger ice ages?

  Soon after launching into this research, Croll read a paper by a brilliant French scientist that set his mind in motion. The idea was that regular variation in Earth’s orbit could change the amount of heat that hits Earth’s surface. Earth spins around the sun, and its tilt brings the seasons. The orbit depends on the proximity of other big celestial bodies nearby: Mars, Jupiter, Venus, and Saturn are all rotating in space as well. As they approach Earth on regular cycles, their large masses warp the orbit and tilt of our planet. In times on the order of thousands of years, Earth’s orbit will wobble and change, thereby influencing the amount of sunlight that warms the planet. Croll reasoned that ice ages happen during regular intervals when the orbit causes the planet to receive less heat from the sun.

  Here was a cause that made a specific prediction: the ice ages should happen at regular intervals defined by the orbit of the planet. Unfortunately for Croll, his theory became just a passing fad. Because he lacked any firm way of matching the timing of the ice ages to orbits, Croll’s theory remained just a good idea.

  Milutin Milankovitch. (Illustration Credit 9.4)

  A few decades after Croll’s death, a young Serbian concrete engineer got the notion that he could use the mathematical talents that were so helpful in designing buildings to uncover how the universe worked. His thinking was revealed in a toast he gave a poet friend after the two shared a bottle of wine in a Belgrade café. The poet had hoisted his glass to proclaim, “I want to describe our society, our country, and our soul.” The concrete engineer countered with the salute, “I want to do more than you. I want to grasp the entire universe and spread light into its farthest corners.”

  Soon after the boast, the engineer, Milutin Milankovitch, switched jobs. Leaving his building firm, he took a professorship at the University of Belgrade. Not easily intimidated, he proceeded to announce that he was out to solve the problems of the planet by pure mathematics. Global climates were his first problem. But not just Earth’s. He wanted to devise a mathematical theory for climate all over the face of Earth and for every other planet in the solar system as well.

  This ambition puzzled a few of his colleagues. Why would you need to calculate global temperatures if we can simply set up weather stations to measure them? Milankovitch’s answer revealed his thinking. If, armed with only pencil and paper, he could predict temperatures mathematically, then we would truly understand their causes. Off he went, looking at the planetary rhythms that so captivated Croll.

  Milankovitch cycles consist of changes in the tilt of Earth, its wobble, and the shape of the orbit around the sun.

  Croll’s ideas were a natural starting point, but Milankovitch brought a huge new twist to the problem. Using orbital calculations similar to Croll’s, Milankovitch explored how sunlight could change the heat of the planet. To elucidate this relationship, he modeled the different ways that heat gained by the ocean can be transferred to the atmosphere and back. A brilliant mathematician, he was able to calculate the magnitude of temperature changes during the seasons, resulting in a remarkably specific set of predictions.

  Earth’s orbit changes in three major ways. Over 100,000 years Earth’s orbit goes from the shape of an oval to a more circular pattern. During 41,000 years Earth rocks back and forth about 2 degrees. And in the course of 19,000 years Earth’s tilt wobbles like a top.

  Milankovitch realized that these are not huge changes, and in fact they would not alter the amount of heat received by Earth much. What they could do, as his equations showed beautifully, is change the duration and intensity of the seasons. And the reason is straightforward: if the seasons depended on the degree Earth is tilted and the manner in which the planet rotates around the sun, then changes to the shape and orientation of the planet and its orbit will affect the heat of summer, the cold of winter, and everything in between.

  The rocks reveal the occurrence of ice ages. Mathematical calculations show that Earth’s climate can change in a cyclic manner, matching the orbital changes of our planet. But do the cycles of ice ages and those of Earth’s orbits march together? Answers would have to wait for new scientific quests—namely, the effort to make the atom bomb.

  CHILLING EVIDENCE

  The Manhattan Project was a short-term war effort that pulled together a unique cadre
of scientists to focus on a single goal. With the war’s end the U.S. government found itself with a problem, but one of those problems that is good to have. It had teams of scientific geniuses housed in different places, from New Mexico to New York, with no long-term infrastructure to continue their work. To make matters more challenging, no longer was there a single goal to their work, like developing a bomb; there were now many. Not wanting to lose the talent, or the momentum generated from fundamental breakthroughs in physics, the government supported a number of labs around the country, including one at the University of Chicago. Chicago was home to the group, led by Enrico Fermi, that launched the first controlled nuclear reaction (today the spot is marked by a Henry Moore sculpture across the street from the gym). After the war, the government helped the university establish a number of institutes exploring the big questions of physics and chemistry. One of those big problems was the history of our planet.

  Two people who benefited from this transition from war to peace science at Chicago, Willard Libby and Harold Urey, shared a passion and a belief. The passion was for expanding knowledge. The belief was that trapped in the dynamics of single atoms—in their electrons, protons, and neutrons—were clues to the origin and history of the planet and perhaps even the entire solar system.

  Driving this exploration of the atom was the development of new devices that could measure particles in parts per billion. With this resolution, new kinds of answers to old questions were now possible.

  Libby set up two junior scientists in his lab with five thousand dollars to carry out a research program on carbon. Like most atoms, carbon exists in a number of different forms in the natural world. All carbon atoms have the same number of protons inside their nuclei; the different versions are distinguished from each other by the number of neutrons inside. Libby’s insight was that all living things will have the same amount of carbon 14 in their bodies as the atmosphere in which they live. Living creatures breathe, eat, and drink carbon atoms in their daily lives and thus share the same balance of carbon with the atmosphere. Once organisms die, this balance with the atmosphere is disrupted, and no new carbon enters as food or nutrients. Whatever carbon atoms remain in the body begin to decay into other forms. As we’ve seen with other atoms, this reaction happens at a constant rate set by the laws of physics and chemistry. Knowing this, Libby ventured that if you can measure the amount of carbon 14 in a sample of old bones, you can, with some assumptions, calculate how long ago the animal died. This was a huge advance: it was like finding clocks inside ancient bones, teeth, shells, and wood.