From a distance it looked like snow: soft white clumps scattered along the slopes and shores of Wrangel Island. Even now, in late summer, it was not unusual to encounter ice in these remote Arctic waters, but snow at low elevations was surprising. As he got closer, ecologist Nikita Zimov became even less certain about the scene before him. The snow seemed to move. Gradually, each clump took on a more distinct shape. They had hummocked backs and thick legs, small black eyes and large round noses. They were, Nikita realized, polar bears. Numerous fully grown polar bears.

Nikita, who was 26 at the time, had traveled to the island on an old gray boat with his father, Sergey Zimov, a renowned Arctic ecologist, and two friends. With the exception of some moderately rough waves and a failed transformer, the first few days of the voyage were surprisingly uneventful. They took turns navigating and scanning for obstacles. They ate ham, eggs, ramen and borscht accompanied by generous pours of beer and vodka. When they weren’t working, they read, played cards, watched movies and slept.

On the fourth day, as they turned away from the coast to make a final dash through the open sea toward their destination, they encountered a massive ice floe. Circumventing it added another three days to the trip. They spent the nights anchored to inlets of ice, some­times sleeping alongside walruses with bristled lips and three-foot tusks that arced from their mouths like ivory sabers.

When the group finally arrived at Wrangel Island, they found a safe spot to dock far from the polar bears. Shipping crates, decaying boats and rusty oil barrels littered the shoreline. Nail-studded boards barri­caded the windows of the few small shacks and houses. The man the Zimovs had come to meet was in the next town over, but evening was rapidly approaching. After enjoying the island’s makeshift sauna, they retreated to their boat and slept until morning.

Lying 90 miles off the coast of Russia, Wrangel Island is a toupee-shaped blob of tundra almost as large as Yellowstone National Park. During the last glacial period, smothering ice sheets bypassed the island, which made it something of a refuge. Mammoths survived there for 6,000 years after all other members of their species had died out, by which point the pyramids of Giza had stood for nearly a millennium. Rus­sia has protected the island as a federal nature reserve since the 1970s.

Today, more than 400 plant species and subspecies take root in Wrangel’s soils. Horned puffins, Pacific loons and peregrine falcons routinely visit. Arctic foxes and wolves stalk lemmings and reindeer; herds of shaggy musk oxen roam the hills; gray whales and belugas shimmer off­shore. Most famously, Wrangel Island is thought to have the highest density of polar bear dens in the world, attracting groups of tourists every year. Other than that, essentially no one is allowed to stay on the island except to conduct scientific research.

Like many scientists, the Zimovs had come to Wrangel Island be­cause of its wildlife. The reserve’s director, Alexander Gruzdev, had promised to give them at least six baby musk oxen. The Zimovs planned to relocate the animals to Chersky, a tiny settlement on the Kolyma River in far northeast Russia, to take part in a daring and ambi­tious scientific project—one that, if their theories were correct, would transform vast tracts of the Arctic landscape and help stabilize Earth’s climate.

On the second morning after their arrival, they finally met up with Gruzdev. Shortly after introducing themselves and glimpsing the paddock hold­ing the musk oxen, they were interrupted by the sound of an imminent invasion. Three large black dinghies were speeding toward shore, each carrying about 20 elderly American tourists. Apparently, a cruise ship from Alaska had anchored nearby so that its passengers could see the polar bears and puffins up close. “You know, I felt like a great ex­plorer of the Arctic when we finally got to the island,” Nikita recalls. But the sight of so many senior citizens reaching the island with such ease, wobbling onto shore with digital cameras in hand, “nullified the experience.”

Gruzdev had previously agreed to help guide the tourists around the island, so he temporarily left the Zimovs to occupy themselves. The Zimovs were still hoping to load their living cargo onto their boat and leave fairly soon. The island had different plans. Later that day, when the Zimovs were resting and neither Gruzdev nor the rangers were in town, a polar bear bashed its way through the wood-and-chicken-wire paddock surrounding seven baby musk oxen. As the bear killed one musk ox, the other six fled—and, with them, the entire reason for the Zimovs’ perilous voyage. The only way to continue their experiment as planned was to somehow reclaim the animals that had escaped, which would likely entail a long and grueling search.

Now in his early 40s, Nikita Zimov is tall and lean with glacier-blue eyes and a boyish mop of brown hair. His sentences tend to swell and swerve like rivers. And he frequently deploys deadpan humor. (“Of course you need to avoid all icebergs,” he told me when recollecting the trip to Wrangel Island. “Or else you can become Titanic number two or three. Smaller scale, but still very sad.”) Sergey, who is approaching 70, is a bearish man with long grizzled hair and a bushy beard. His forehead is creased and his lower eyelids pouchy. He speaks slowly and ponderously in broken English, often slipping into bouts of scientific soliloquy. Together, the Zimovs and their spouses, Galina and Anastasia, run the Northeast Science Station in Chersky, one of the largest and most important centers of science in the Arctic.

Sergey Zimov first traveled to the high Arctic in the 1970s to study its paleogeography—its an­cient landscapes. As he worked, he became fascinated by the unexpected abundance of bones. When Sergey surveyed his research site, he rarely saw wildlife. Yet, wherever he dug, he found the bones of long-dead ani­mals and bygone species. The ground was a graveyard full of mammoths with spiraling tusks, humpbacked bison, maneless cave lions, elk with 80-pound antlers and an extinct species of rhinoceros nicknamed “the Siberian unicorn” for the single giant horn on the top of its head.

Becoming Earth: How Our Planet Came to Life

A vivid account of a major shift in how we understand Earth, from an exceptionally talented new voice.

Geologists call the period of Earth’s history spanning from approx­imately 2.6 million years ago to 12,000 years ago the Pleisto­cene. For the last 100,000 years of that epoch, extensive grasslands ringed the northerly latitudes of the globe. Known as the mammoth steppe, they made up one of the largest and most productive ecosystems that has ever existed. The mammoth steppe supported incredible numbers of giant herbivores and hulking predators. When the Pleistocene ended, the grasslands and nearly all their colossal inhabitants disappeared. One question haunted Sergey in particular: What happened?

To Sergey, the prevailing explanation—climate change—did not make sense. Gargantuan mammals had survived hundreds of millions of years of repeated glaciations and thaws. Why would they suddenly ex­pire during this one episode of warming in this long-running pattern? Sergey favored a different cause: humans. Humans were gnats in a world of titans, but their ingenuity and manual dexter­ity, combined with strategic cooperation, eventually made them super-predators. As humans ascended, Sergey reasoned, the planet’s giants dwindled. Geoscientist Paul Martin and climatologist Mikhail Budyko had al­ready published similar ideas in the late 1960s, inciting a debate that continues to this day. In the past decade, however, the argument that humans hunted Pleistocene megafauna into extinction has gained con­siderable support from new archaeological and fossil evidence.

Sergey’s most important insight was that such a widespread extinc­tion would inevitably have serious ecological repercus­sions for the planet as a whole. He and other scientists have proposed that certain grasses negotiated a symbiosis with large herbivores. The grasses of­fered grazers endless fields of tender green leaves that quickly regenerated when shorn. In exchange, megafauna trampled, ate and otherwise deterred the grasses’ main botanical competitors, such as shrubs and trees, and fertilized the fields with their copious dung. Together, the theory goes, grasses and megafauna maintained the mammoth steppe eco­system.

In turn, Sergey reasoned, the mammoth steppe would have influenced the planet’s climate. In the Pleistocene, as today, thick layers of frozen soil known as permafrost lay beneath the Arctic’s surface, concealing a vast reservoir of carbon. If the temperature rose high enough, the permafrost began to thaw, allowing microbes to break down its organic matter and potentially releasing potent greenhouse gases such as carbon dioxide and methane in suffi­cient quantities to warm the planet.

But the steppe itself could counteract such warming. Because grasses were typically paler than trees and many other plants, they bounced more light back into space, cooling Earth. Grasses also captured enormous amounts of carbon from the atmosphere and stored it in deep, diffuse roots. In winter, large herbivores stripped away heat-trapping layers of snow through the simple act of walking on the ground with their considerable heft as well as by digging through the snow to forage. In doing so, they exposed the permafrost to frigid winter tem­peratures, ensuring that it remained frozen. When humans killed off most of the world’s megafauna, they did much more than reduce Earth’s biodiversity—they also impaired its ability to regulate global climate.

The complex ecological bonds between grazers, grasslands and cli­mate emerge from one of the most important transformative processes in the Earth system: co-evolution, the reciprocal evolution of two or more entities. Although co-evolution usually refers to interacting species, such as flowering plants and pollinators, it can also occur between other entities. Memes, technologies and cultures can co­-evolve, for instance. Life and its environment evolve together, too. Dar­winian evolution by natural selection happens through changes to the genetic composition of populations whose members vary in their traits. Those individuals best able to survive and reproduce in their particular environment leave behind the most offspring and pass on the genes cod­ing for the very traits that made them so successful. Generation by gen­eration, those genes and traits become more common in the overall population. Thus, species adapt to their environments.

But their physical environments do not remain fixed during this process, nor are they sub­ject to purely geological change. As living creatures evolve, they alter their surroundings extensively. Some of those changes persist and inevi­tably influence any evolution that follows. In this way, life becomes an agent in its own evolution. Natural selec­tion is embedded within, and influenced by, the reciprocal transforma­tion of organisms and their domains. Life and environment continuously shape one another and Earth as a whole.

By the time Sergey had put together many of the pieces of his the­ory, it was the late 1980s and he was running the Northeast Science Station. Nikita was still a toddler. When Sergey looked at the land surrounding the station, he saw a frozen desert. Most of the Arctic had essentially become “weeds covering the ceme­tery of mammoth steppe,” Sergey told me.

Wherever fire or human activity dis­turbed the soil and displaced the moss, however, grass flourished. What if, Sergey wondered, it were possible to recreate the mammoth steppe? What would happen if he brought herbivores back to the Arctic? It would be a perfect way to test his theory.

Sergey proposed his idea to some of the leading Russian scientists at the time. Impressed, they agreed to a small field experiment with Yakutian horses. Within months, grass began to grow. Levels of nitrogen and phosphorus increased ten­fold. Then, in 1991, the Soviet Union collapsed and the government support for Sergey’s newest study evaporated.

Sergey persisted. He realized that if enough permafrost thawed due to global warming, the released carbon di­oxide and methane could trigger runaway global warming. (Some scientists have since challenged this idea.) The resurrection of the mammoth steppe could thwart this awful fate.

In convincing other scientists of the connection between his re­search and climate change, Sergey endowed his project with re­newed urgency and importance. In the late 1990s, the Russian government gave him a little over 35,000 acres of protected tundra and bo­real forest surrounding the Chersky research station to use for his ex­periment. He formally designated the area Pleistocene Park, a winking reference to a certain science fiction franchise based on the premise of reviving dinosaurs. He suddenly had more than enough land for his ambitious project. Now he just needed some animals.

Nikita Zimov was running across the chapped terrain of Wrangel Island, wrapped in curtains of fog, when he thought he heard a polar bear. Dread pressed in on him from all sides. Silently, he cursed his foolishness.

After losing the baby musk oxen, the Zimovs, their companions and Gruzdev had boarded ATVs and begun a search. At some point, Nikita, proud of his youth and fitness, had decided to run alongside the vehicles. Now, he was lost, alone and, in his own typically under­stated words, “a bit worried.” When he had agreed to help his father with Pleistocene Park after graduating from college, this was not what he had envisioned. He kept running through the fog until, by chance, he found one of his friends and hastily climbed aboard their ATV .

Whenever the Zimovs and their search party located a herd of musk oxen, they surrounded them with a circle of ATVs so that Gruzdev could shoot a tranquil­izer dart at one of the calves. A few minutes later, after the calf col­lapsed, the search party would slowly push the herd away. Catching even a single animal in this manner was extremely challenging. Harsh conditions slowed them down and reduced visibility. The tranquilizers were sometimes too weak to render a calf fully unconscious. And it could take five or six hours just to find a herd.

After eight days of roaming the tundra, they finally recaptured six baby musk oxen. There was just one step left before they could call their expedition a success: They needed to return safely to Chersky. Only this time, they had to make the trip with a new group of large, hungry, nervous passengers who had never before left home and knew nothing of the sea.

Excerpted from Becoming Earth: How Our Planet Came to Life by Ferris Jabr. Published by Random House. Copyright © 2024. All rights reserved.

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