2-Million-Year-Old DNA Could Aid the Fight Against Climate Change – DISCOVER Magazine
According to a paper published in Nature, researchers recently found fragments of Ice Age DNA in sediment samples taken from northern Greenland. Tracing back to two million years ago, these fragments are a million years older than any others on record, and they expose an ancient ecosystem capable of enduring extreme climate conditions.
“A new chapter spanning one million extra years of history has finally been opened,” says Eske Willerslev, a paper author and a director of the Lundbeck Foundation GeoGenetics Centre at the University of Copenhagen, according to a press release.
In fact, the researchers assert that these fragments — in addition to explaining ancient environments — could play a part in forecasting the future of modern climate change. More than that, they add that the DNA could also contribute to making today’s most threatened species more resilient to the increasingly severe climate conditions to come.
DNA in the Dirt
In recent years, the DNA stuck in ancient sediments has arisen as an important source of information about ecosystems from thousands of years ago. That said, scientists still struggle to extract and analyze DNA from sediments over a million years old, even when it was preserved under the best conditions (those that are cold and dry).
Now, innovative techniques for removing and assessing ancient DNA have helped researchers study two-million-year-old fragments from the Kap København formation in the northernmost portion of Greenland. One million years older than the world’s next oldest DNA (which was sampled from a wooly mammoth skeleton from Ice Age Siberia), these particular fragments have ushered in a new era in the study of past ecosystems.
“DNA can degrade quickly, but we’ve shown that under the right circumstances, we can now go back further in time than anyone could have dared imagine,” Willerslev states. “For the first time, we can look directly at the DNA of a past ecosystem that far back.”
Ultimately, the researcher’s analysis painted a picture of an ecosystem filled with a diversity of different bushes, birds, mammals and microorganisms, all of which could survive severe climate conditions. In fact, the temperatures in Greenland two million years ago were somewhat volatile, vacillating between around 18 and 31 degrees Fahrenheit warmer than they are currently.
“The Kap København ecosystem, which has no present-day equivalent, existed at considerably higher temperatures than we have today,” says Mikkel W. Pedersen, another study author and geologist at the Lundbeck Foundation GeoGenetics Centre, in a press release. “The climate seems to have been similar to the climate we expect on our planet in the future due to global warming.”
This similarity between past and predicted temperatures in Greenland, the researchers say, means that their research could illuminate the consequences of climate change on modern-day environments, particularly in terms of biodiversity.
“The data suggests that more species can evolve and adapt to wildly varying temperatures than previously thought,” Pedersen states. “But, crucially, these results show they need time to do this. The speed of today’s global warming means organisms and species do not have that time, so the climate emergency remains a huge threat to biodiversity.”
Moreover, the researchers advance that they may be able to transfer the survival strategies and skills ingrained in the two-million-year-old DNA to some of today’s at-risk species, and plants in particular, to protect them against perpetually increasing temperatures.
“It is possible that genetic engineering could mimic the strategy developed by plants and trees two million years ago to survive in a climate characterized by rising temperatures and prevent the extinction of some species,” says Kurt H. Kjær, another study author and geologist at the Lundbeck Foundation GeoGenetics Centre, in a press release. “This is one of the reasons this scientific advance is so significant, because it could reveal how to attempt to counteract the devastating impact of global warming.”
The Dirty Details
To arrive at their results, the researchers recovered 41 separate samples of clay and quartz from the over 320-foot-thick formation, which sits in the shallows of a fjord.
“The ancient DNA samples were found buried deep in sediment that had built-up over 20,000 years,” Kjær states. “The sediment was eventually preserved in ice or permafrost and, crucially, not disturbed by humans for two million years.”
After finding out that there were, in fact, fragments of DNA trapped in the clay and quartz samples, the researchers removed the many fragments and studied them. Comparing them all to the DNA of modern species, the researchers found that a diversity of different microorganisms, plants and animals dotted the ancient environment, including birch trees, reindeer and hares. Even elephant-like mastodons trampled through Greenland two million years ago, they found, before eventually becoming extinct.
Showing striking similarities to the DNA of several modern species, some of the fragments provided a peek at the unfamiliar ancestors of today’s most familiar microorganisms, plants and animals. Yet other fragments posed much more of a challenge to interpret and understand, originating from species that have been long forgotten by today’s system of classification. An in-depth illustration of the interactions between these organisms, whether familiar or not, will be presented in future research, the authors say.
“It wasn’t until a new generation of DNA extraction and sequencing equipment was developed that we’ve been able to locate and identify extremely small and damaged fragments of DNA in the sediment samples,” Kjær concludes in a press release. “It meant we were finally able to map a two-million-year-old ecosystem.”