A freezer for ancient worlds
The Verkhoyansk Mountain Range in the Sakha Republic of Siberia is one of the coldest places on Earth. Beneath its sparse tundra, the ground is permanently frozen solid in a deposit called permafrost, which in this region can be 100 to 600 meters thick. Much of this frozen earth is a specific type known as Yedoma, a sediment with ice and organic material from the Pleistocene epoch. Formed up to 1.8 million years ago, Yedoma contains between 50 and 90 percent ice by volume and holds the preserved remains of ancient plants and animals.
This permafrost acts as a stable, deep-freeze environment, preserving biological material with remarkable fidelity. As global temperatures rise, however, these ancient deposits are beginning to thaw. This thawing can cause the ground to collapse, creating massive geological features called thermokarst slumps. The largest of these, the Batagaika crater, is nearly 300 feet deep, covers over 200 acres, and is expanding by as much as 98 feet per year. While this rapid thaw releases trapped greenhouse gases like methane, it also exposes a perfectly preserved cross-section of the Pleistocene world, revealing everything from extinct megafauna to viable microorganisms.
Life revived from the ice
The organic material locked inside the Verkhoyansk permafrost is a library of dormant life. Scientists have successfully revived organisms that have been in a state of suspended animation for tens of thousands of years. In 2012, researchers regenerated a flowering plant, Silene stenophylla, from 32,000-year-old fruit tissue found in an ancient squirrel burrow buried 38 meters deep. These resurrected Ice Age plants grew, flowered, and produced their own viable seeds.
Even more complex organisms have been reawakened. Nematode roundworms have been brought back to life after being frozen for up to 46,000 years. After being thawed and placed in a petri dish with nutrients, the microscopic worms began to move and eat. Perhaps most strikingly, scientists have isolated and revived multiple ancient viruses. One amoeba-infecting virus, named Pandoravirus yedoma, was revived from a 48,500-year-old permafrost sample, making it the oldest virus to return to an infectious state. Another giant virus, Pithovirus sibericum, was found to be active after 30,000 years in the ice. These "zombie viruses" currently only infect single-celled organisms, but their existence shows what other ancient microbes might awaken as the permafrost thaws.