The Universe Within
Neil Shubin ’82 explores the common history of rocks, planets and people
Neil Shubin ’82 is the Robert R. Bensley Professor, organismal biology and anatomy, and associate dean for academic strategy at the University of Chicago. He was elected to the National Academy of Sciences in 2011.
A distinguished paleontologist, Shubin has developed
expeditionary research programs in realms as far afield as Asia, Africa and
Greenland. In his first book, the best-selling Your Inner Fish: A Journey into the
3.5-Billion-Year History of the Human Body [see cover story, March/April
2011], he traced the links between human anatomy and that of the fish that
first came onto land hundreds of millions of years ago. His latest volume, The
Within: Discovering the Common History of Rocks, Planets, and People, provides an even broader map of our vast existence. Shubin, as The Wall Street Journal points out, “tracks the very atoms in our bodies back to the Big Bang … What is special about the book is its sweep, its scope, its panorama.”
In the following excerpt from The Universe Within, Shubin describes the high drama of a scientific expedition in the frozen ridges of Greenland.
Rose Kernochan ’82 Barnard
Viewed from the sky, my companion and I must have looked like two black specks perched high on a vast plain of rock, snow, and ice. It was the end of a long trek, and we were slogging our way back to camp on a ridge sandwiched between two of the greatest ice sheets on the planet. The clear northern sky opened a panorama that swept from the pack ice of the Arctic Ocean in the east to the seemingly boundless Greenland ice cap to our west. After a productive day prospecting for fossils and an exhilarating hike, and with the majestic vista around us, we felt as if we were walking on top of the world.
Our reverie was abruptly cut short by a change in the rocks beneath our feet. As we traversed the bedrock, brown sandstones gave way to ledges of pink limestone that, from our earlier discoveries, became an auspicious sign that fossils were in the neighborhood. After we spent a few minutes peering at boulders, alarm bells went off; my attention was pulled to an unusual glimmer flashing from a corner of a melon-sized rock. Experience in the field taught me to respect the sensation triggered by these moments. We had traveled to Greenland to hunt for small fossils, so I hunched over my magnifying lens to scan the rock closely. The sparkle that arrested me sprang from a little white spot, no bigger than a sesame seed. I spent the better part of five minutes curled up with the rock close to my eyes before passing it to my colleague Farish for his expert opinion.
Concentrating attention on the fleck with his lens, Farish froze solid. His eyes shot back to me with a look of pent-up emotion, disbelief, and surprise. Rising from his crouch, he took off his gloves and launched them about twenty feet in the air. Then he nearly crushed me with one of the most titanic bear hugs I have ever received.
Farish’s exuberance made me forget the near absurdity of feeling excitement at finding a tooth not much bigger than a grain of sand. We found what we had spent three years, countless dollars, and many sprained ligaments looking for: a 200-million-year-old link between reptiles and mammals. But this project was no miniature trophy hunt. The little tooth represents one of our own links to worlds long gone. Hidden inside these Greenlandic rocks lie our deep ties to the forces that shaped our bodies, the planet, even the entire universe.
Seeing our connections to the natural world is like detecting the pattern hidden inside an optical illusion. We encounter bodies, rocks, and stars every day of our lives. Train the eye, and these familiar entities give way to deeper realities. When you learn to view the world through this lens, bodies and stars become windows to a past that was vast almost beyond comprehension, occasionally catastrophic, and always shared among living things and the universe that fostered them.
How does such a big world lie inside this tiny tooth, let alone inside our bodies? The story starts with how we ended up on that frozen Greenlandic ridge in the first place.
Imagine arriving at a vista that extends as far as the eye can see, knowing you are looking inside it for a fossil the size of the period that ends this sentence. If fossil bones can be small, so too are whole vistas relative to the surface area of Earth. Knowing how to find past life means learning to see rocks not as static objects but as entities with a dynamic and often violent history. It also means understanding that our bodies, as well as our entire world, represent just moments in time.
The playbook that fossil hunters use to develop new places to look has been pretty much unchanged for the past 150 years. Intellectually, it is as simple as it gets: find places on the planet that have rocks of the right age to answer whatever question interests you, rocks of the type likely to hold fossils, and rocks exposed on the surface. The less you have to dig, the better. This approach, which I described in Your Inner Fish, led me and my colleagues, in 2004, to find a fish at the cusp of the transition to life on land.
As a student in the early 1980s, I gravitated to a team that had developed tools to make headway finding new places to hunt fossils. Their goal was to uncover the earliest relatives of mammals in the fossil record. The group had found small shrewlike fossils and their reptilian cousins in a number of places in the American West, but by the mid-1980s their success had brought them to an impasse. The problem is best captured by the jest, “Each newly discovered missing link creates two new gaps in the fossil record.” They had done their share of creating gaps and were now left with one in rocks about 200 million years old.
The search for fossil sites is aided by economics and politics. With the potential for significant oil, gas, and mineral discoveries, there are incentives for countries to catalog and map the geology exposed inside their borders. Consequently, virtually any geological library holds journal articles, reports, and, one hopes, maps detailing the age, structure, and mineral content of the rocks exposed on the surface of different regions. The challenge is to find the right maps.
Professor Farish A. Jenkins Jr. led the team at Harvard’s Museum of Comparative Zoology. Fossil discovery was the coin of the realm for him and his crew, and it started in the library. Farish’s laboratory colleagues Chuck Schaff and Bill Amaral were key in this effort; they had honed their understanding of geology to predict likely places to make discoveries, and, importantly, they trained their eyes to find really small fossils. Their relationship often took the form of a long, friendly argument: one would propose a new idea while the other would relentlessly try to quash it. If the idea held up under their largely amiable tit for tat, then they would both line up behind the proposal and take it to Farish, with his keen logistic and scientific sense, for vetting.
One day in 1986, while chewing the fat with Chuck, Bill found a copy of the Shell Oil Guide to the Permian and Triassic of the World on Chuck’s desk. Paging through the volume, Bill spotted a map of Greenland, with a little hatched area of Triassic rocks on the eastern coast at a latitude of about 72 degrees north, roughly that of the northernmost tip of Alaska. Bill kicked things off by proclaiming that this could be a prime next area to work. The usual argument ensued, with Chuck denying that the rocks were the right type, Bill responding, and Chuck countering.
By dumb luck, Chuck had the means to end the debate right on his bookshelf. A few weeks earlier, he was trolling through the library discards and pulled out a paper titled “Revision of Triassic Stratigraphy of the Scoresby Land and Jameson Land Region, East Greenland,” authored by a team of Danish geologists in the 1970s. Little did anyone know at the time, but this freebie, saved from the trash heap, was to loom large in our lives for the next ten years. Virtually from the minute Bill and Chuck looked at the maps in the reprint, the debate was over.
My graduate student office was down the hall, and as was typical for that time in the late afternoon, I swung by Chuck’s office to see what was what. Bill was hovering about, and it was clear that some residue from one of their debates remained in the air. Bill didn’t say much; he just slapped Chuck’s geological reprint down in front of me. In it was a map that showed exactly what we had hoped for. Exposed on the eastern coast of Greenland, across the ocean from Iceland, were the perfect kinds of rocks in which to find early mammals, dinosaurs, and other scientific goodies.
The maps looked exotic, even ominous. The east coast of Greenland is remote and mountainous. And the names evoke explorers of the past: Jameson Land, Scoresby Land, and Wegener Halvø. It didn’t help matters that I knew that a number of explorers had perished during their trips there.
Fortunately, the expeditions that transpired ultimately rested on Farish’s, Bill’s, and Chuck’s shoulders. With about sixty years of fieldwork between them, they had developed a deep reservoir of hard-earned knowledge about working in different kinds of field conditions. Of course, few experiences could have prepared us for this one. As a famed expedition leader once told me, “There is nothing like your first trip to the Arctic.”
I learned plenty of lessons that first year in Greenland, ones that were to become useful when I began running my own Arctic expeditions eleven years later. By bringing leaky leather boots, a small used tent, and a huge flashlight to the land of mud, ice, and the midnight sun, I made so many bad choices that first year that I remained smiling only by reciting my own motto, “Never do anything for the first time.”
The most nerve-racking moment of that inaugural trip came when selecting the initial base camp, a decision made in a fleeting moment while flying in a helicopter. As the rotors turn, money flies out the window, because the costs of Arctic helicopters can be as high as three thousand dollars per hour. On a paleontology budget, geared more to beat-up pickups than to Bell 212 Twin Hueys, that means wasting no time. Once over a promising site revealed by the maps back in the laboratory, we rapidly check off a number of important properties before setting down. We need to find a patch of ground that is dry and flat yet still close to water for our daily camp needs, far enough inland so that polar bears aren’t a problem, shielded from the wind, and near exposures of rock to study.
We had a good idea of the general area from the maps and aerial photographs, and ended up setting down on a beautiful little patch of tundra in the middle of a wide valley. There were creeks from which we could draw water. The place was flat and dry, so we could pitch our tents securely. It even had a gorgeous view of a snowy mountain range and glacier on the eastern end of the valley. But we would soon discover a major shortcoming. There were no decent rocks within easy walking distance.
Once camp was established to our satisfaction, we set off each day with one goal in mind: to find the rocks. We’d climb the highest elevations near camp and scan the distance with binoculars for any of the exposures that figured so prominently in the paper Bill and Chuck had found. Our search was eased by the fact that the rock layers were collectively known as red beds for their characteristic hue.
With red rock on our minds, we went off in teams, Chuck and Farish climbing hills to give them views of the southern rocks, Bill and I setting off for places that would reveal those to the north. Three days into the hunt, both teams returned with the same news. Out in the distance, about six miles away to the northeast, was a sliver of red. We’d argue about this little outcrop of rock, scoping it with our binoculars at every opportunity for the remainder of the week. Some days, when the light was right, it seemed to be a series of ridges ideal for fossil work.
It was decided that Bill and I would scout a trail to get to the rocks. Since I didn’t know how to walk in the Arctic, and had made an unfortunate boot selection, the trek turned out to be an ordeal — first through boulder fields, then across small glaciers, and pretty much through mud for the rest of the way. The mud formed from wet clay that made an indelicate glurp as we extricated our feet from each step. No footprint remained, only a jiggling viscous mass.
In three days of testing routes, we plotted a viable course to the promising rocks. After a four-hour hike, the red sliver in our binocular view from camp turned out to be a series of cliffs, ridges, and hillocks of the exact kind of rock we needed. With any luck, bones would be weathering out of the rock’s surface.
The goal now became to return with Farish and Chuck, doing the hike as fast as possible to leave enough time to hunt for bones before having to turn back home. Arriving with the whole crew, Bill and I felt like proud homeowners showing off our property. Farish and Chuck, tired from the hike but excited about the prospect of finding fossils, were in no mood to chat. They swiftly got into the paleontological rhythm of walking the rocks at a slow pace, eyes on the ground, methodically scanning for bone at the surface.
Bill and I set off for a ridge about half a mile away that would give us a view of what awaited us even farther north. After a small break, Bill started to scan the landscape for anything of interest: our colleagues, polar bears, other wildlife. He stopped scanning and said, “Chuck’s down.” Training my binoculars on his object, I could see Chuck was indeed on his hands and knees methodically crawling on the rock. To a paleontologist this meant one thing: Chuck was picking up fossil bones.
Our short amble to Chuck confirmed the promise of the binocular scan; he had indeed found a small piece of bone. But our hike to this little spot had taken four hours, and we now had to head back. We set off, with Farish, Bill, Chuck, and me in a line about thirty feet apart. After about a quarter of a mile something on the ground caught my eye. It had a sheen that I’d seen before. Dropping to my knees like Chuck an hour earlier, I saw it in its full glory, a hunk of bone the size of my fist. To the left was more bone, to the right even more. I called to Farish, Bill, and Chuck. No response. Looking up, I knew why. They were also on their hands and knees. We were all crawling in the same colossal field of broken bones.
At summer’s end, we returned boxes of these fossil bones to the lab, where Bill put them together like a three-dimensional jigsaw puzzle. The creature was about twenty feet long, with a series of flat leaf-shaped teeth, a long neck, and a small head. The beast had the diagnostic limb anatomy of a dinosaur, albeit a relatively small one.
This kind of dinosaur, known as a prosauropod, holds an important place in North American paleontology. Dinosaurs in eastern North America were originally discovered along streams, railroad lines, and roads, the only places with decent exposures of rocks. The eminent Yale paleontologist Richard Swann Lull (1867–1957) found a prosauropod in a rock quarry in Manchester, Connecticut. The only problem was that it was the back end. The block containing the front end, he was chagrined to learn, had earlier been incorporated into the abutment of a bridge in the town of South Manchester. Undeterred, Lull described the dinosaur from its rear end only. When the bridge was demolished in 1969, the other fragments came to light. Who knows what fossil dinosaurs remain to be discovered deep inside Manhattan? The island’s famous brownstone town houses are made of this same kind of sandstone.
The hills in Greenland form large staircases of rock that not only break boots but also tell the story of the stones’ origins. Hard layers of sandstones, almost as resistant as concrete, poke out from softer ones that weather away more quickly. Virtually identical staircases lie farther south; matching sandstones, siltstones, and shales extend from North Carolina to Connecticut all the way to Greenland. These layers have a distinctive signature of faults and sediment. They speak of places where lakes sat inside steep valleys that formed as the earth fractured apart. The pattern of ancient faults, volcanoes, and lake beds in these rocks is almost identical to the great rift lakes in Africa today — Lake Victoria and Lake Malawi — where movements inside Earth cause the surface to split and separate, leaving a gaping basin filled by the water of lakes and streams. In the past, rifts like these extended all the way up the coast of North America.
From the beginning, our whole plan was to follow the trail of the rifts. Knowing that the rocks in eastern North America contained dinosaurs and small mammal-like creatures gave us the aha moment with Chuck’s geological reprint. That, in turn, led us north to Greenland. Then, once in Greenland, we pursued the discoveries on the ground like pigeons following a trail of bread crumbs. It took three years, but clues in the red beds ultimately led us to that frozen ridge I trekked with Farish.
From the top of the ridge, the tents of camp looked like tiny white dots just below the horizon. The crest was windswept, but the bluff of pink limestone on which we were seated formed a quiet shield for Farish and me to assess the discovery. Farish’s jubilation confirmed my hunch that the white spot in the rock was indeed a mammal tooth. With the characteristic pattern of three cusps and two roots, it was a dead ringer for one of these beasts.
Armed with confidence that came from this first discovery, the team looked widely across east Greenland, eventually finding better mammal fossils in subsequent years. The fossils came from a small shrewlike animal about half the size of a house mouse. Although it lacks the sort of awe-inspiring skeleton that would grace a museum rotunda, its beauty lies elsewhere.
This is one of the first creatures in the fossil record with our kind of teeth: those with cutting surfaces defined by cusps that occlude on upper and lower teeth with a tooth row subdivided into incisors, canines, and molars. It has an ear that is like ours also, containing little bones that connect the eardrum to the inner ear. Its skull pattern, shoulder, and limb are also decidedly mammalian. We don’t know for sure, but it likely had hair and other mammalian features such as milk-producing glands. Every time we chew, hear high pitches, or rotate our hands, we use parts of our anatomy that can be traced through primates and other mammals to the structures in these little creatures from 200 million years ago.
The rocks also tie us to the past; rifts in Earth, like those that led us to find fossil mammals in Greenland, have left their traces in our bodies as much as they have in the crust of the planet. The Greenlandic rocks are like one page in a vast library of volumes that contain the story of our world. Billions of years of history preceded that little tooth, and 200 million years have followed it. Through eons on Earth, seas have opened and closed, mountains have risen and eroded, and asteroids have come crashing down as the planet has coursed its way through the solar system. The layers of rock record era after era of changes to the climate, atmosphere, and crust of the planet itself. Transformation is the order of the day for the world: bodies grow and die, species emerge and go extinct, while every feature of our planetary and celestial home undergoes gradual change or episodes of catastrophic revolution.
Rocks and bodies are kinds of time capsules that carry the signature of great events that shaped them. The molecules that compose our bodies arose in stellar events in the distant origin of the solar system. Changes to Earth’s atmosphere sculpted our cells and entire metabolic machinery. Pulses of mountain building, changes in orbits of the planet, and revolutions within Earth itself have had an impact on our bodies, minds, and the way we perceive the world around us.
From the Book: THE UNIVERSE WITHIN by Neil Shubin. Copyright © 2013 by Neil Shubin. Published by arrangement with Pantheon Books, an imprint of The Knopf Doubleday Publishing Group, a division of Random House LLC.