The stones vault overhead to form a basalt arch, named for President Theodore Roosevelt, who laid the cornerstone in 1903. Soon the road starts to climb, switchbacking up and up, between the Gardner River and the cliffs the river has carved, jagged rock faces where bighorn sheep wander and feed. Crest the rise and enter Mammoth, Wyo., seat of Yellowstone National Park.
Mammoth is a place with potential as enormous as its name. For most visitors, it is the diving board into the park’s wonders—mountains and meadows, streams and lakes, waterfalls and geysers. Bears and wolves live here. So do elk, bison, coyotes, beavers—an ark’s worth of life forms, from large to small. Some are very, very small.
For University of Illinois geobiologist Bruce Fouke, Mammoth also is a jumping-off point leading to a vaster realm—one that reaches from the clouds to deep below the Earth and back up again into the intricacies of the human body and the mysteries of the universe. Fouke studies the hot spring terraces at Mammoth, where water that fell from the sky long ago now bubbles up from underground and courses downhill, leaving behind limestone in terraces both tall and tiny, enduring and ephemeral. This phenomenon is just one in Yellowstone’s extraordinary range of geysers, fumaroles and hot springs. The park’s location over an ancient supervolcanic caldera grants it more than 12,500 hydrothermal features, outnumbering those of any other site in the world.
Limestone forms where flowing water acts on layers of sediment and rock to create calcium carbonate (CaCO3). At Mammoth Hot Springs, that CaCO3 limestone—better known as travertine—is forming faster than usual. Like, a billion times faster. Ask how this could be, and Fouke has a two-word answer: Sulfurihydrogenibium yellowstonense. It’s a bacterium that lives deep among the rocks. It rides to the surface on water super-heated by magma and reacts with oxygen and sulfur at the surface to create travertine. Sulfuri is but one of an as-yet-uncounted array of heat-loving bacteria, archaea and algae—life forms known collectively as microbes—that live among rocks in the Earth’s outer crust and are found in the thermal features of Yellowstone.
Fouke has been familiar with Yellowstone for most of his life. As a child, he spent summers there when his father, a Methodist minister, was stationed there as a park chaplain. The family home was in rural Iowa, where Fouke grew corn and beans and raised hogs, and found the occasional chunk of fossilized coral-rich limestone lingering from when vast inland seas covered the Midwest.
In his junior year at Bradley University in Peoria, Ill., Fouke became entranced by the images of “volcanoes and mountains and oceans and ice sheets” he saw during a lecture on earth science; he promptly changed his major from civil engineering to geology. Graduate school at Stony Brook (N.Y.) University led to a stint in the Caribbean studying coral reefs—which are, like the Yellowstone terraces, calcium carbonate structures built by living organisms. He then worked at the Free University in Amsterdam on the biosignatures of reefs around the world—the story left behind by generations of microbes in layers of coral. From there, it was an improbable but productive leap to Berkeley, Calif., and postgraduate research on what happened to the dinosaurs.
From Berkeley, it was on to a stint at NASA’s Ames Research Center in Mountain View, Calif., where the space agency was working on its 1996 Pathfinder mission to Mars. Fouke studied the geologic connections between fossils in coral reefs and evidence of life on other planets. Seeing that coral and travertine have much in common—both are made of CaCO3 and both form in salty water—he decided to look for more answers at Mammoth Hot Springs.
Microbes are everywhere on Earth—including in people, where they make up an estimated 90 percent of the body’s cells. Continuing study of the “microbiome” reveals important information about the colonies of bacteria that live within human beings and assist in digestion and fighting off disease. In nature, microbes perform photosynthesis, absorb carbon dioxide, and eat elements such as sulfur and salt. Harnessed by manufacturing and medicine, they create enzymes, impel fermentation, clean up waste and produce medications.
The potential and importance of microbes can’t be overstated. Thermus aquaticus, informally known as Taq, was discovered in Yellowstone’s Lower Geyser Basin in 1966. Taq provided the molecular template for polymerase chain reaction, also known as PCR, a laboratory technique that amplifies copies of DNA segments. PCR led to the field of genomic research, reducing the time needed to analyze genomes from years to hours and spawning a trillion-dollar industry.
Fouke’s own work wends and arcs in an eclectic and fascinating journey. In addition to the hot springs in Yellowstone and the coral reefs of the Caribbean, he has studied Roman aqueducts (which have their own deposits of travertine), helped create a database for managing Yellowstone research and published prolifically in scholarly journals. He teaches undergraduate courses—including a massive open online course (MOOC) with enrollments that top out at 50,000 each year—and has guided more than 1,000 UI students on field trips to Yellowstone’s hot springs and the southern Caribbean’s coral reefs. Fouke serves as director of the University’s Carver Biotechnology Center, which provides scientists at Illinois with instruments and computing resources for the analysis of DNA, RNA and living cells.
Fouke and M.D./Ph.D. student Jessica Saw are collaborating on research with the Mayo Clinic on human kidney stones. The team is investigating conditions under which calcium oxalate stones precipitate in the kidney, a process that has similarities to the formation of both travertine and coral skeletons. The goal is to discover whether kidney stones can be dissolved in the body, potentially offering an alternative to the painful options of passing the stone or undergoing surgery.
All life has poured forth from microbes. The trout, trees, elk, wild grass, butterflies—the countless animals and plants of Yellowstone and of the world come from far-distant ancestors of tiny creatures living in boiling water and rocks. And the organization of this family tree could apply to life elsewhere in the solar system and the universe.
This cosmic diversity is the subject of The Art of Yellowstone Science, a book published in 2016 by Fouke and nature photographer Tom Murphy. Paired with Murphy’s spectacular images of the park’s thermal features, landscapes and wildlife, Fouke’s text takes the reader through geologic time and evolutionary science toward an understanding of how the wonders of Yellowstone resound far beyond its natural beauty and intriguing creatures.
Amid the nation’s tug-of-war over natural resources, which veers between preservation and exploitation, Fouke’s argument is compelling. And it isn’t new. In the 1872 act that created Yellowstone, the U.S. Congress summed up the value of nature with a strong, simple phrase. These words endure in the stones of the arch that heralds one of the most fabulous wildernesses areas in the world. They proclaim Yellowstone to be “For the Benefit and Enjoyment of the People.” It was a principle to live by in 1872, as it is now, and will be (in the work and hope of Bruce Fouke) forever.
Geology Professor Lijun Liu has addressed the possibility of a volcanic catastrophe at Yellowstone. The park sits on a huge caldera; it has long been thought to be at risk for earthquake and supervolcano eruption brought on by a rising subsurface material known as a mantle plume. Using the Blue Waters supercomputer, Liu and his team of graduate students modeled the region’s subsurface geology based on seismological data. The results show that the heat that fuels Yellowstone comes from beneath the Pacific Ocean rather than from a mantle plume.
Robert Pahre, professor of political science, offers an undergraduate class on the politics of the greater Yellowstone area. Students spend almost two weeks in Yellowstone and Grand Teton National Park, learning about the policy challenges the parks face. Course topics range from tourism and the meaning of wilderness to how the movements of animals across boundaries (such as wolves and bison venturing outside the parks) create tensions in the community. Pahre’s research deals with how humans relate to nature, and how humans relate to one another in natural landscapes such as Yellowstone and other national parks.
UI Microbiologist Rachel Whitaker studies microbes in the hot springs of Yellowstone, where much of her research focuses on Sulfolobus islandicus, an archaea found in acidic streams and pools. Last year, she received the Allen Distinguished Investigator Award—a prestigious international honor funding research on viruses and evolution—supporting her future work investigating regions of the genome capable of moving rapidly between cells, hastening genetic change.
Norman Denzin, emeritus professor of sociology, is the author of Searching for Yellowstone: Race, Gender, Family and Memory in the Postmodern West. In this work, published in 2008, Denzin writes about how living near Yellowstone shaped his views on such topics as the Lewis and Clark expedition, tourism and 21st-century representations of Native Americans.
Carl R. Woese (1928-2012) is immortally linked to his discovery of single-celled organisms called archaea. But Woese did much more than this to upend and restructure taxonomy and evolutionary theory. A biophysicist and microbiologist, Woese joined the University of Illinois faculty in 1964. His intensive study of DNA and RNA led him and his collaborator, postdoctoral researcher George Fox, to advance the then-controversial argument that the universal tree of life consists of three branches: bacteria, archaea (both microbial life forms) and eucarya (complex life forms, including humans). Even more revolutionary was their idea that genetic mutations can be shared laterally (within generations) as well as vertically (from generation to generation, according to the Darwinian model). Woese based these findings on years of painstaking manual molecular sequencing using X-rays of DNA.
Woese and Fox proposed archaea as the third domain of life in 1977, having first found them in the stomach of a cow on the UI campus at the College of Veterinary Medicine. The researchers went on to confirm the existence of archaea, using 16S RNA gene sequences collected in Octopus Spring—a hydrothermal feature in Yellowstone National Park. The Carl R. Woese Institute for Genomic Biology at Illinois was renamed in his honor in 2015.—M.T.