First Contact

by Marc Kaufman

  Our group of scientists was outfitted in overalls highlighted with fluorescent striping, heavy rubber boots and goggles, hard hats capped with a miner’s light, and a mandatory safety kit strapped to our belts, including a breathing device that can filter out carbon monoxide. The chatter ended as we were ushered into the manager’s cage; the miners piled into another. The doors slammed shut and both cages picked up speed, plunging down to Level 7—a thirty-miles-per-hour express ride into the crust of the Earth, accompanied by the sound of falling rocks hitting our carrier as we sped by. We jolted to a stop, an attendant pried the door half open, and we stumbled out into a high-ceilinged, man-made chamber that housed a rail yard for miniature ore trains. Accompanied by an array of mine officials, we passed through this small island of light and set off for the outer reaches of Level 7. We were 1.1 miles below ground and surrounded everywhere by dark, gloomy rock.

  The scientists, a South African, a Belgian, and a Spaniard all affiliated with the Extreme Biochemistry group at the University of the Free State in Bloemfontein, some three hundred miles away, have descended many times into the deep underworld in search of extreme forms of life. It remains a daunting—and risky—venture, but the search for extremophiles is sending researchers to scores of equally harsh environments around the world. The results have led to a revolution in thinking about the tenacity and adaptability of life, which has been found to thrive in ice a mile deep, in hot springs, in highly acidic rivers, in and around the scalding thermal vents at the bottom of the ocean. The word extremophile, after all, means literally a lover of extreme places. For them, it’s our world that’s toxic.

  At Northam Platinum, each turn on the journey to the Level 7 outskirts led to a smaller, darker, hotter tunnel. Like the strands of a spiderweb, the tunnels radiate out from the center in a mazelike order, logical yet quickly incomprehensible to the unguided. The dry path gave way to sloppy mud from the water seeping through the fissures of the rocks, boot-grabbing stuff that hid the old railway ties and pipes waiting to trip us up. A massive ventilation system worked to keep the heat down, pumping air and sometimes water through wide, striated tubing made of dun-colored fabric. Fastened to the sides of the winding tunnels, they gave new visual meaning to the phrase “bowels of the Earth.” But that monumental ventilation effort provided limited relief: Ambient temperatures spike with any significant drop into the Earth, and Northam Platinum has an additional heat load to cope with. The radioactive decay of granite in the Bushveld area has long been especially active, and the result is greater than usual subterranean heat.

  Time slipped away in the dark sameness of the march. We passed loudly buzzing ventilation substations, rest areas where sooty and muddied African miners were far less likely to talk or smile than those on ground level, and some tunnel branches sealed up with hazard signs warning of methane gas or rock slides or water. I could tell we were nearing our destination when the temperature spiked. We were in a dark, dead-end area that housed an array of equipment installed to (with only limited success) stop a flow of water into the tunnel. The lights from our miners’ hats gave fleeting glimpses of the spectral landscape. All around, the soggy heat had aged the gears, chains, and metal slabs in fast-forward, producing what looked like a very long-ago, sea-bottom shipwreck. Dripping stalactites of calcium carbonate took the place of seaweed; corrosion and rust replaced the barnacles. Water dripped from small fracture holes in the rock, spat out of a corroded valve, and drained into a shin-deep pool. I reached out to touch the spray, and it was bathwater hot.

  The most excited man in the darkness was Gaetan Borgonie of the University of Ghent in Belgium, a nematodologist on the verge of a potentially major discovery. He had set out a few years before in search of new varieties of minuscule but ubiquitous and extraordinarily hardy roundworms—which aren’t really worms at all but rather are called nematodes. These creatures, Borgonie was eager to explain to me, are many-celled and have both a nervous system and a digestive tract. They are among the most primitive life forms to have that in-and-out system, a rudimentary nervous system, and the ability to reproduce both sexually and as single-sex hermaphrodites. He thought that finding these complex creatures alive this deep in the netherworld would be the first strong signal that more complex life just might survive alongside single-cell bacteria and other microbes deep below the inhospitable surface of Mars or other celestial bodies—places where the sun also never shines, and where the products of sunshine are similarly completely absent. Nematodes, and even three-foot-long tube worms, were discovered some decades ago at or near the dark bottom of the deep ocean, but the extraterrestrial implications of their discovery were less dramatic because the creatures fed on life produced in collaboration with the sun, nourishment that then made the long drop to the ocean floor.

  Borgonie’s search had taken him to the tiny Caribbean island of St. Croix, to a sulfur-based ecosystem in Mexico, and finally to the South African–American team that had pioneered deep-mine searches for bacteria. Over the past two years, Borgonie—who as a young man wanted to be an astronaut but now was regularly headed in the opposite direction—had descended into South African mines more than twenty times, and had found (along with his colleagues) an impressive number of nematodes and their eggs in gold, platinum, and diamond mines as far down as 2.2 miles. Most had come out of capped boreholes, but not all: He had also learned on previous samplings that before the minerals harden to produce the long, hard stalactites hanging before us, they sculpt cones that, while still wet, can provide an improbable home to his nematodes and their eggs.

  Virtually nobody in the field (including the committee at his university that granted him a sabbatical) believed his deep-mine nematode research would succeed because, on land, the worms are known to live only in the soil and near subsoil. He was eager to test his dissenting views and hopeful that he would confirm that nematodes (like bacteria) can also adapt to life deep underground, and to determine how they got there and whether they’ve been there long enough to evolve into unique creatures.

  “These are good, very good,” he said to nobody in particular as he waded back and forth between the stalactites hanging from the spectral ironworks on the walls and the measuring and collecting instruments stored in a beaten-up backpack. He carefully removed several cones and collected the precious drips from others. “This system they’ve worked out is just beautiful to think about and to see,” he said.

  It was time to go to our primary destination—another dead-end tunnel a little farther on with a borehole that was running especially hot water. The Northam mine’s chief geologist knew about the extremophile hunters from Bloemfontein and called van Heerden to tell her the team might want to come down to take a look before the section was dynamited.

  Having left the shipwreck site, I marched behind the others. It was unnerving to be so far underground, so completely surrounded by rock. But the tunnel was straight and solidly dug, the ventilation brought in some fresh air and took out the noxious gases, and the periodic sight and sound of miners down branch tunnels kept things from becoming too otherworldly. I came to a junction, made a sharp left to follow the others, and, with the suddenness of a fast-passing train, was staggered by a blast of heat. I reached for the wall to keep standing. Working in this kind of heat is known to bring on hallucinations, and for the next half hour I periodically did see halos of light far broader than anything coming from my miners’ lights. Only later did I learn that both Gaetan and Derek Litthauer, a rugged and experienced professor and mine diver from Bloemfontein, have on occasion been evacuated from an especially hot or airless tunnel and sent back to the surface.

  I inched my way to the researchers and mine officials gathered ahead. Already the scientists had attached their equipment to a narrow metal pipe poking out from the rock and were collecting water. It was a borehole, one drilled by miners to see what conditions were like inside the rock. The temperature gauge showed the water was a scalding 150 degrees at the end of the pipe. Mine geolo
gist Werner Lamprecht, clearly proud of the extremity of it all, said the temperature several feet inside the rock face was probably in the range of 170 degrees. Steam danced up from the water pooled on the tunnel floor.

  I sat on a discarded board beside the tunnel wall and watched. The tunnel had no insects, no spiders, none of the unexpected movement that comes with creatures. Yet previous expeditions had proven that we were not alone—that even this place somehow supported life in the tiny, watery cracks in the rock face, in the dripping stalactites, and who knows where else. We knew something was there because four years earlier Onstott had already discovered several microbes at or near the bottoms of South African deep gold operations. One, located in 2005 in this same Northam Platinum mine, 1.2 miles down, was a highly unusual “star” bacterium featuring a four-to-nine-point star formation—an adaptation that allows it to capture more of the “food” it needs to survive with increased surface area.

  It was hard for the parboiled scientists to stay at the final collection site, but it was also hard to pull away, since they never know when they’ll be invited for a return expedition. They had a dozen or more tests to conduct, and a variety of filters to place on the flowing water in the hopes of collecting unusual bacteria, nematodes, or something even more unexpected. But as excitement gave way to exhaustion, they packed up for the hike back to the cages. They knew they had to conserve energy because they would return the next morning to collect their filters with the miners’ morning shift at 4 A.M.

  There’s an inevitable needle-in-a-haystack quality to these subterranean searches—the mines are huge, and the hiding places for microbes and nematodes are small and dispersed—and so Borgonie was not particularly disappointed when initial cultures and examinations in the lab came up empty for nematodes from Northam Platinum. The setting still seemed hospitable for his “worms,” especially if his theories were on target about how the nematodes follow their prey (the bacteria) through rock cracks to the deep underground, and then adapt to life there. But nobody strikes gold with every dig. The samplings continued, and the very next week, at the gold mine at Driefontein to the southwest, his fortunes changed dramatically. The catch: four healthy nematodes. In all, he found worms or their eggs in seven of more than twenty deep underground South African mine sites he sampled over six months—a discovery that, if nailed down, would dramatically change our understanding of what can survive in the deep netherworld and how it comes to be down there.

  Borgonie left for Belgium soon after to spend some time in his lab in Ghent. He hadn’t initially planned to return to South Africa, but the lure of the mines and the creatures they hide quickly pulled him back—especially once he was able to convince Onstott to join him in writing the scientific paper they hoped would introduce the “worms from Hell” to the world. This time Borgonie would place filters on the boreholes and leave them for weeks or months to see what else might be living in the rocks.

  Six months later, Borgonie, Onstott, and their colleagues were convinced they had, for the first time, detected the presence of multicelled organisms up to 2.5 miles below the Earth’s surface. Several samples had been cultured and had begun to squirm and even reproduce asexually in the lab. The team tested for possible contamination—nematodes brought in on miners’ shoes, or deep “old” water that somehow had mixed with water from near the surface—and found that the nematodes coming out of the rock were different from anything found in the tunnels. (They didn’t include the nematodes found in the stalactites in the paper because Borgonie concluded their presence raised too many extraneous questions.) What’s more, the water used for ventilation and cleaning in the mines contains chemicals that kill bacteria and nematodes—strengthening the case that the creatures Borgonie had found in his filters came out from deep in the rock, and not from a miner’s boot. Carbon 14 dating of the “worms” and their remains indicated they had been living in the netherworld at least 4,000 to 12,000 years—less time than the team had expected, but perhaps an insight into what allows the worms to survive and what kills them. The older water—millions of years under the surface—has virtually no available oxygen, while the younger water appears to have just enough to keep the aerobic nematodes alive. The team’s excitement was palpable. As Borgonie and Onstott said in a summation of their work, “The presence of nematodes kilometers beneath the surface of the Earth is like finding Moby-Dick in Lake Ontario.”

  Once the research is published, scientists will pick it apart, assessing whether the data about contamination is convincing and whether nematodes can really live in an environment so hot, so lacking in oxygen, and with so little food. The discovery suggests that nematodes, which are already known to live around deep-ocean hydrothermal vents in temperatures as high as 180 degrees Fahrenheit, probably also live below the ocean floor and should be pursued there. Living below ground and below the ocean floor would give the minuscule worms an advantage when it comes to the catastrophes and mass extinctions that have struck Earth several times; it would be their refuge.

  Borgonie was relieved his physically-punishing and time-consuming nematode bet had paid off. When future scientists start digging in earnest on Mars, he now had to believe, similar surprises could easily await them.

  It turns out that extremophiles—mostly denizens of the bacteria and related archaea kingdoms—are everywhere on Earth. They have been found around scalding Pacific Ocean hydrothermal vents called “black smokers”—where “hyperthermophiles” live under pressure four hundred times greater than the Earth’s surface atmosphere and temperatures at the vent mouths can reach 750 degrees Fahrenheit. Yellowstone National Park has also yielded organisms growing and reproducing in water hotter than 180 degrees Fahrenheit. The Rio Tinto in Spain flows red and is highly acidic (with a pH of about 2) yet it is home to not only extreme bacteria, but also to other highly unusual and more complex organisms. The uplands of the river have been mined for five thousand years, but the tailings created are not generally considered the cause of the extreme acidity; rather, it is the extremophiles in the river feeding on the iron and sulfide minerals in the riverbed that produce, and thrive in, the resulting acid bath. Researchers already know that microbes live in clouds and are sending balloons up to the stratosphere (one hundred thousand feet up) and finding living organisms there, too. Indian scientists launched a helium-filled balloon in 2009 and found microbes alive between 12 and 25 miles up into the stratosphere, where usually fatal ultraviolet radiation is strong. The implications for extraterrestrial life are pretty clear: Life, if given an environment even the slightest bit friendly, will find a way to adapt and survive.

  In 1998, even before many of the most dramatic extremophile finds were made, a prominent University of Georgia microbiologist named William “Barny” Whitman asserted in the Proceedings of the National Academy of Sciences that half or more of the biomass on Earth, the intact cells of creatures, plants, and single-cell organisms, lives thirty feet or more below the surface of the land and four inches or more below the bottom of the oceans. Since then, experts have debated the details of the estimate by Whitman and his colleagues, but have accepted the conclusion that of the life on Earth—the cells that make up all the insects, trees, mice, birds, fish, bacteria, and us—about half consists of those invisible to the eye, single-cell organisms that live below the ocean and below the ground.

  Their conclusion, so at odds with how most of us understand the planet on which we live, will perhaps make this additional insight into the extremophile world more palatable: Researchers are also finding microbial life in the ice of the world’s thickest and coldest glaciers, in the so-called cryosphere.

  The presence of organisms near the top of a glacier, where sunlight can warm and liquefy the ice, seems to make sense, as does microbial life along the glacier’s ever-moving bottom, where the Earth’s geothermal warmth and the glacier’s friction create a somewhat watery environment. But recent discoveries have included the presence of organisms, or organism remains, at almost any de
pth measurable. While the research isn’t conclusive, it certainly appears that some are not in a dormant or spore phase, but rather are actively metabolizing chemical impurities in the ice, using them as an energy source to maintain the disequilibrium needed for life and to repair their DNA, and to consequently live for impossibly long periods of time. This most extreme of ecosystems is apparently made possible by an unusual but universal property of glacial and sea ice: Those seemingly solid blocks actually contain a maze of minuscule veins that can include liquid water in ice to very low temperatures. This can happen because the physics of ice crystallization pushes all extraneous salts, minerals, and organisms into these microscopic pathways, creating environments where a microbe would have the nutrients and the unfrozen water needed to live. Some of the pioneering work in this field is being done in the unlikely and balmy setting of Baton Rouge, Louisiana.

  On the day I visited Louisiana State University and its glacial life program, it was in the seventies outside. Students were mostly wearing shorts and T-shirts, and the world was green and soft. In the cold room where program director Brent Christner and his students do their work, the temperature was a steady 23 degrees Fahrenheit. We had on parkas and lots of polar fleece. Working in the icy cold has left at least one of the grad students perpetually chilled and wearing a down parka as he walks around campus.

  The two-hundred-square-foot cold room is for studying the ice and houses a workstation with high-precision air quality control, a light box, a band saw, a subzero growth incubator, and an air vent—under which the “windchill factor” drops even further. But the real treasure trove is through another thick, tightly latched door into a –20-degrees storeroom filled with ice cores and ice blocks from around the world, and especially from Antarctica. Wrapped in heavy-duty plastic bags and stored in see-through container boxes from Home Depot, the ice looks as lifeless and exciting as cement. But Christner knows better; years of work have shown that they contain microorganisms barely eking out a living, yet apparently metabolizing, using energy, maintaining their DNA and splitting—all at a, well, glacial pace. Christner is confident this is correct because he has observed microbes that have been frozen in ice for many thousands of years start wiggling when warmed up a bit in the lab. Working with Mark Skidmore of Montana State University, Christner and his team, the Interdisciplinary Collaboration Investigating Biological Activity in a Subglacial Environment (ICIBASE), are finding recently unimaginable activity at the icy boundaries of life.