Researchers in a warming Arctic are discovering organisms, frozen and presumed dead for millennia, that can bear life anew. These ice age zombies range from simple bacteria to multicellular animals, and their endurance is prompting scientists to revise their understanding of what it means to survive.
“You wouldn’t assume that anything buried for hundreds of years would be viable,” said La Farge, who researches mosses at the University of Alberta. In 2009, her team was scouring Teardrop’s margin to collect blackened plant matter spit out by the shrinking glacier. Their goal was to document the vegetation that long ago formed the base of the island’s ecosystem.
“The material had always been considered dead. But by seeing green tissue, “I thought, ‘Well, that’s pretty unusual,’ ” La Farge said about the centuries-old moss tufts she found.
She brought dozens of these curious samples back to Edmonton, lavishing them with nutrient-rich soils in a bright, warm laboratory. Almost a third of the samples burst forth with new shoots and leaves. “We were pretty blown away,” La Farge said. The moss showed few ill effects of its multi-centennial deep-freeze.
Tatiana Vishnivetskaya has studied ancient microbes long enough to make the extreme feel routine. A microbiologist at the University of Tennessee, Vishnivetskaya drills deep into the Siberian permafrost to map the web of single-celled organisms that flourished ice ages ago. She has coaxed million-year-old bacteria back to life on a petri dish. They look “very similar to bacteria you can find in cold environments (today),” she said.
But last year, Vishnivetskaya’s team announced an “accidental finding” – one with a brain and nervous system – that shattered scientists’ understanding of extreme endurance.
As usual, the researchers were seeking singled-celled organisms, the only life-forms thought to be viable after millennia locked in the permafrost. They placed the frozen material on petri dishes in their room-temperature lab and noticed something strange. Hulking among the puny bacteria and amoebae were long, segmented worms complete with a head at one end and anus at the other – nematodes.
“Of course we were surprised and very excited,” Vishnivetskaya said. Clocking in at a half-millimeter long, the nematodes that wriggled back to life were the most complex creatures Vishnivetskaya – or anyone else – had ever revived after a lengthy deep freeze.
She estimated one nematode to be 41,000 years old – by far the oldest living animal ever discovered.