The Ice Age conjures images of vast frozen landscapes, but it wasn’t always this frigid. At some points during this era, warmer ice-free periods allowed life to thrive.
Now, scientists have discovered two million-year-old DNA from one such period in Greenland, and they believe their ancient findings could serve as a “road map” for our future. It’s the oldest DNA discovered to date, beating the previous record by a million years.
The DNA discovery is sixteen years in the making for the researchers. They published their work Wednesday in the journal Nature.
“It’s just an unbelievable feeling,” Eske Willerslev, one of the leading researchers on the study, told reporters during a press conference. Willerslev is a professor of ecology and evolution at the University of Cambridge and director of the University of Copenhagen's Center of Excellence GeoGenetics.
How they made the finding — Typically, to understand how life flourished in the past, researchers uncovered and analyzed fossils. But fossils are incredibly rare and difficult to find, limiting our understanding of the past.
The ancient world found hidden in the DNA is one that is very different from our own but could become more imaginable as global warming continues.
So, the research team behind the Nature paper turned their attention to extracting DNA from the environment. This genetic material, known as environmental DNA or eDNA, comes from organisms from the past that shed DNA to their surroundings, such as in terrestrial areas or bodies of water. Researchers today can extract and sequence it to understand our ancient environment better.
“Every single cell in the body contains DNA. So we are walking around on DNA from the present,” Willerslev said in a video summary of the report.
The scientific team began their research sixteen years ago in the Kap København Formation — presently a barren Arctic desert in North Greenland. But it wasn’t until a few years ago that they were able to improve their DNA extraction technology enough to remove the genetic information from mineral deposits in a shallow bay in the region.
“The ancient DNA samples were found buried deep in sediment that had built up over 20,000 years. The sediment was eventually preserved in ice or permafrost and, crucially, not disturbed by humans for two million years,” Kurt Kjær, a professor at the University of Copenhagen’s GeoGenetics Center, said in a press release.
After extracting the DNA, the researchers compared the fragments to existing genetic databases on plant and animal wildlife. It was a small DNA sampling — less than a millimeter in length — but it contained volumes of information about the ancient world.
What they found — The researchers were surprised to learn just how long DNA can remain intact. The team aged the newly discovered DNA to be about two million years old. Willerslev previously thought DNA could only survive for a million years, but his own research proved him wrong.
“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 said.
When they analyzed this ancient DNA, they found it contained genetic evidence of a multitude of plants and animals. The team identified 102 genera — scientific classes — of plants like the Arctic plant Dryas integrifolia and trees like cedar and poplar, which we would find today farther south in Canada’s boreal forests.
They also uncovered nine broad categories of animals, including expected species like geese and hares but also unexpected ones like reindeer and horseshoe crabs, which typically reside much farther south in waters warmer than those found in Greenland.
“...we can now go back further in time than anyone could have dared imagine”
“This is an ecosystem with no modern analog. It’s a mix between temperate and Arctic species. You don’t see that today,” Willerslev said
The DNA revealed the presence of ancient mastodons — elephant-like creatures that were slightly smaller than wooly mammoths — which surprised and thrilled researchers, who hadn’t speculated they would find evidence of such large animals.
“My mind was blown,” Willerslev said.
Why it matters — The ancient world found hidden in the DNA is one that is very different from our own but could become more imaginable as global warming continues.
The scientists found both Arctic and temperate species living together in the Kap København Formation, an ecosystem that simply does not exist in our modern world. Researchers say these animals that typically thrive in warmer climates could have survived in the climate of ancient Greenland, which was an average of 11 to 19 degrees Celsius above current temperatures.
The adaptability of the animal and plant life was “much higher than we imagined,” Willerslev said, adding that their findings demonstrate “how nature can respond to increasing temperatures.”
If ancient Greenland really is a warning of our climate future, then scientists say we should act on the knowledge gained from studying this ancient DNA. Willerslev believes the DNA could serve as a road map to edit the “genetic makeup of plants and animals to become more resilient to climate change” potentially thwarting mass extinctions.
What’s next — The researchers were able to unlock DNA in the cold far reaches of Greenland, where climate conditions favor the preservation of DNA. Next summer, they plan to head to Canada to conduct similar DNA extraction in an equally chilly environment.
They also want to expand their research to warmer climates — a potential challenge since DNA is preserved best in colder climates. But since the scientists were able to extract DNA from clay and quartz for the first time in Greenland, they hope to do the same on the opposite end of the globe. Expanding their research to Africa — where humans originated — could shed light on the beginning of humanity.
“If we can begin to explore ancient DNA in clay grains from Africa, we may be able to gather ground-breaking information about the origin of many different species —perhaps even new knowledge about the first humans and their ancestors,” Willerslev said.
