Living plants have been generated from the fruit of a little arctic flower, the narrow-leafed campion, that died 32,000 years ago, a team of Russian scientists reports. The fruit was stored by an arctic ground squirrel in its burrow on the tundra of northeastern Siberia and lay permanently frozen until excavated by scientists a few years ago.
This would be the oldest plant by far that has ever been grown from ancient tissue. The present record is held by a date palm grown from a seed some 2,000 years old that was recovered from the ancient fortress of Masada in Israel.
Seeds and certain cells can last a long term under the right conditions, but many claims of extreme longevity have failed on closer examination, and biologists are likely to greet this claim, too, with reserve until it can be independently confirmed. Tales of wheat grown from seeds in the tombs of the pharaohs have long been discredited. Lupines were germinated from seeds in a 10,000-year-old lemming burrow found by a gold miner in the Yukon. But the seeds, later dated by the radiocarbon method, turned out to be modern contaminants.
Despite this unpromising background, the new claim is supported by a firm radiocarbon date. A similar avenue of inquiry into the deep past, the field of ancient DNA, was at first discredited after claims of retrieving dinosaur DNA proved erroneous, but with improved methods has produced spectacular results like the reconstitution of the Neanderthal genome.
The new report is by a team led by Svetlana Yashina and David Gilichinsky of the Russian Academy of Sciences research center at Pushchino, near Moscow, and appears in Tuesday’s issue of The Proceedings of the National Academy of Sciences of the United States of America.
“This is an amazing breakthrough,” said Grant Zazula of the Yukon Paleontology Program at Whitehorse in Yukon Territory, Canada. “I have no doubt in my mind that this is a legitimate claim.” It was Dr. Zazula who showed that the apparently ancient lupine seeds found by the Yukon gold miner were in fact modern.
But the Russians’ extraordinary report is likely to provoke calls for more proof. “It’s beyond the bounds of what we’d expect,” said Alastair Murdoch, an expert on seed viability at the University of Reading in England. When poppy seeds are kept at minus 7 degrees Celsius, the temperature the Russians reported for the campions, after only 160 years just 2 percent of the seeds will be able to germinate, Dr. Murdoch noted.
The Russian researchers excavated ancient squirrel burrows exposed on the bank of the lower Kolyma River, an area thronged with mammoth and woolly rhinoceroses during the last ice age. Soon after being dug, the burrows were sealed with windblown earth, buried under 125 feet of sediment and permanently frozen at minus 7 degrees Celsius.
Some of the storage chambers in the burrows contain more than 600,000 seeds and fruits. Many are from a species that most closely resembles a plant found today, the narrow-leafed campion (Silene stenophylla).
Working with a burrow from the site called Duvanny Yar, the Russian researchers tried to germinate the campion seeds, but failed. They then took cells from the placenta, the organ in the fruit that produces the seeds. They thawed out the cells and grew them in culture dishes into whole plants.
Many plants can be propagated from a single adult cell, and this cloning procedure worked with three of the placentas, the Russian researchers report. They grew 36 ancient plants, which appeared identical to the present day narrow-leafed campion until they flowered, when they produced narrower and more splayed-out petals. Seeds from the ancient plants germinated with 100 percent success, compared with 90 percent for seeds from living campions.
The Russian team says it obtained a radiocarbon date of 31,800 years from seeds attached to the same placenta from which the living plants were propagated.
The researchers suggest that special circumstances may have contributed to the remarkable longevity of the campion plant cells. Squirrels construct their larders next to permafrost to keep seeds cool during the arctic summers, so the fruits would have been chilled from the start. The fruit’s placenta contains high levels of sucrose and phenols, which are good antifreeze agents.
The Russians measured the ground radioactivity at the site, which can damage DNA, and say the amount of gamma radiation the campion fruit accumulated over 30,000 years is not much higher than that reported for a 1,300-year-old sacred lotus seed, from which a plant was successfully germinated.
The Russian article was edited by Buford Price of the University of California, Berkeley. Dr. Price, a physicist, chose two reviewers to help him. But neither he nor they are plant biologists. “I know nothing about plants,” he said. Ann Griswold, a spokeswoman for PNAS, as the journal is known, said the paper had been seen by an editorial board member who is a plant biologist.
Tragedy has now struck the Russian team. Dr. Gilichinksy, its leader, was hospitalized with an asthma attack and unable to respond to questions, his daughter Yana said on Friday. On Saturday, Dr. Price reported that Dr. Gilichinsky had died of a heart attack.
Eske Willerslev, an expert on ancient DNA at the University of Copenhagen, said the finding was “plausible in principle,” given the conditions in permafrost. But the claim depends on the radiocarbon date being correct: “It’s all resting on that — if there’s something wrong there it can all fall part.”
If the ancient campions are the ancestors of the living plants, this family relationship should be evident in their DNA. Dr. Willerslev said that the Russian researchers should analyze the DNA of their specimens and prove that this is the case. However, this is not easy to do with plants whose genetics are not well studied, Dr. Willerslev said.
If the claim is true, then scientists should be able to study evolution in real time by comparing the ancient and living campions. Possibly other ancient species can be resurrected from the permafrost, including plants that have long been extinct.
What’s happening in Siberia’s thawing permafrost and Greenland’s melting glaciers sounds borderline supernatural. Ancient viruses, bacteria, plants, and even animals have been cryogenically frozen there for millennia—and now, they are waking up.
Cryofreezing is best known for its appearances in science fiction, but self-styled “resurrection ecologists” are now showing the world just how real it is. In 2012, scientists germinated flowers from a handful of 32,000 year old seeds excavated from the Siberian tundra. Last year, researchers hatched 700-year old eggs from the bottom of a Minnesota lake, while another team resuscitated an Antarctic moss that had been frozen since the time of King Arthur. Bacteria, however, are the uncontested masters of cryogenics—one bug, at least, was alive and kicking after 8 million years of suspended animation.
Fear not—while awakening a million-year old plague sounds like a great scifi plot, most of these critters are totally harmless. But they’re fascinating for another reason: They’re a window into Earth’s past; one that may offer clues to how species will cope with change in the future. Here’s what the emerging field of resurrection ecology—which is as badass as it sounds—may allow scientists to do.
Evolutionary biologists are accustomed to thinking about deep time—events that occurred millions, even billions of years in Earth’s past. Using fossils, rocks and chemical signatures, scientists have built beautifully detailed theories about what our ancient world looked like. Still, if there’s one thing any dino researcher would kill for, it’d be the chance to see one of her long-lost subjects in the flesh.
For the first time now, biologists can do just that—study live organisms that hail from a different era. Sure, bacteria and mosses are a far cry from a T-rex, but being able to poke and prod any creature that crawled about a million years ago is still astounding. As scientists described in the 2013 resurrection ecology manifesto, cryogenically frozen specimens are like an “evolutionary time machine.” They offer researchers a new way to study the past, but also, the chance to observe evolution in real time.
What would it mean to see evolution in action? Going back to dinosaurs for a moment, imagine you’re a paleontologist studying the evolution of feathers. It’d sure be nice if you could clone some dinos, rear them in your Jurassic Park-sized lab, expose them to a range of different environmental conditions—evolutionary biologists call these “selective pressures”—and re-create the “scenario” that caused plumage to evolve. Clearly, this particular experiment is preposterous and will never happen.
But with microbes, which multiply in minutes and pack by the billions into a petri dish, researchers can now do something similar. Imagine you’re a microbiologist studying an striking, pink bacterium that lives in the Canadian Arctic. You collect some permafrost samples from your study site, bring them back to the lab, and are astounded to unearth another colorful bug— only this one’s blue, and it’s been frozen for 3,000 years. You sequence the two critters’ DNA and find out that they’re close genetic cousins. What’s more, you’re able to pin down a single gene responsible for the unusual coloration. Somewhere along the line, it seems, changes in this color gene switched the critters from blue to pink.
Now you’re ready to simulate evolution. You take your pink and blue bugs, and you grow them in the lab under a host of conditions—varying things like temperature, salinity, and pH. After months of hard work, you’re amazed to discover that one of the blue colonies has turned pink. Sure enough, the genetic switch that controls the bug’s color has changed, as well. Congratulations: You’ve just recreated evolution, and you’ve done it in months rather than millennia.
Bear in mind that this is oversimplifying how evolution works. But this simple example illustrates the essential promise that resurrection ecology holds. Scientists can now study how ancient genes behave in a modern environment, and perhaps run experiments that recreate evolution itself.
Another fascinating application of resurrection ecology may be to help endangered species by giving them a genetic “boost.” When a population dwindles, it loses something even more precious than numbers—genetic diversity. Diversity strengthens populations by giving them the tools to cope with new threats, such as climate change or emerging disease. Species that experience this sort of genetic “bottleneck” are often left vulnerable to extinction.
Conservation geneticists are now using the principle that diversity brings strength to try and fortify highly endangered species. Researchers at the non-profit Revive and Restore, for instance, are using cryo-preserved tissue samples to pilot-test genetic rescue techniques on the black footed ferret, a species that escaped extinction by a hair’s breadth but was left genetically impoverished.
The black footed ferret is a special case, because scientists are lucky to have well-preserved tissue samples that harbor some of the animal’s lost genetic diversity. As written about last fall, scientists are just now developing a global network of cryobanks that’ll serve as a genetic repository for thousands more species in the future. But for some organisms, a cryobank may already exist in nature.
In 2012, scientists resurrected permafrost-entombed tissues of Silene stenophylla, a tiny, flowering plant of the Siberian arctic. Within the genetic code of these Ice Age flowers, the researchers found traits that no longer exist in the plant’s modern counterpart, including different flower morphologies and sexual characteristics. This study sparked excitement that, in the future, resurrection of ancient life may offer us a way to reintroduce lost diversity.
One of the strangest and most profound ideas that’s emerged in resurrection ecology. Earth’s climate, as we know, swings hot and cold through natural geologic cycles. During ice ages, the planet’s reservoir of frozen seeds, eggs, plants and microbes build up, but when the Earth warms, so, too, do these cryobanks. The reintroduction of “lost” genes may not be human invention at all, but rather, a natural process that’s been occurring since life first emerged on this rock.