At one point after the last ice age, parts of the North Sea were dry land, and you could walk from mainland Europe into what is now Britain. A new study suggests that route was not a barren plain, but a temperate landscape with oaks, elms, and hazels growing more than 16,000 years ago. The evidence comes from ancient DNA preserved in seafloor sediments.
That matters because Doggerland, the now-submerged landmass that once connected Great Britain to mainland Europe, has often been treated like a simple “land bridge” in the story of early migration.
By pulling genetic clues out of marine mud, researchers argue it was also a refuge for plants and animals, and likely people too. They also report signs that some parts may have stayed above water longer than many timelines assumed.
A forest hidden under the North Sea
The research team found genetic traces of temperate trees in sediments dating back beyond 16,000 years, earlier than many pollen records on land would lead you to expect. Lime tree DNA also appears about 2,000 years earlier than records from mainland Britain, hinting that Doggerland may have sheltered warmth-loving species during colder times.
In a further surprise, the sediment carried DNA from Pterocarya, a walnut relative thought to have disappeared from northwestern Europe around 400,000 years ago.
Professor Robin Allaby of the University of Warwick said the team “unexpectedly found trees thousands of years earlier than anyone expected.” He added that the data point to the North Sea fully forming later than previously thought.
How scientists read DNA from mud
So what is sedimentary ancient DNA, often shortened to sedaDNA? It is a method that pulls tiny genetic fragments from layers of silt and sand, then matches those fragments to known plants and animals. Think of it as a time capsule, except the “capsule” is mud.
In this study, the team analyzed sedaDNA from 252 sediment samples taken from 41 marine cores along a prehistoric river system they call the Southern River. The river itself was about 19 miles long, with an estuary where fresh water met the sea and where resources may have clustered in ways that drew wildlife and people.
Not all mud is equally trustworthy, and the authors leaned into that reality. Their model suggests silty and fine sand deposits can contain DNA signals that are 95 to 98% local, while coarse sands and gravels can be 60 to 70% mixed signals from reworked sediments. In plain terms, some layers tell a clean story and others are a jumble.
Sequential maps illustrate the gradual flooding of Doggerland, the lost land that once connected Europe and Britain.
Microrefugia and the mystery of fast-returning forests
For decades, scientists have debated how trees moved back into northern Europe so quickly after the last ice age. Seeds do not travel fast on their own, so how did forests rebound at the pace the evidence seems to show?
One answer is “microrefugia,” small pockets of livable habitat that protect plants through harsh climate swings. The Doggerland findings support that idea, suggesting some temperate species survived farther north than classic refuges in southern Europe, then spread from nearby once conditions eased. It is survival by hiding in the right places.
A landscape that could feed people and animals
Doggerland did not just host trees, at least not if the ecosystem worked the way modern forests do. The University of Warwick notes that woodland habitats would have supported forest animals such as wild boar, well before the rise of the Maglemosian culture around 10,300 years ago. A place like that is more pantry than passageway.
The paper also points to archaeological hints that fit that picture, including a worked stone tool recovered from an area near the Southern River’s estuary. It is not proof of a bustling settlement, but it does suggest people were present in or near this drowned landscape during the early Holocene.
Allaby put the human side plainly, saying the findings are “the best evidence that Doggerland’s wooded environment could have supported early Mesolithic communities.” In other words, this was not just a corridor you hurried across – it may have been a place you stayed.
When the water rose and the “lost world” broke apart
The story ends the way many coastal stories end, with water creeping in. Doggerland was gradually submerged as seas rose after the last ice age, turning a connected plain into islands and low-lying coastlines, then into the North Sea we know today.
The analysis suggests that parts of Doggerland endured dramatic shocks along the way, including the Storegga tsunami about 8,150 years ago. The researchers also report evidence that some areas may have remained above water until roughly 7,000 years ago, which hints at a slower final disappearance than the popular image of a sudden drowning.
There is an uncomfortable modern echo here, even if the timelines are different. When sea level shifts, landscapes fragment, and the plants and animals living there have to either adapt, move, or disappear.
What Doggerland adds to today’s environmental conversations
It is easy to think of ancient DNA as an archaeology tool, useful mainly for museum debates. In practical terms, it is also becoming a way to track how ecosystems respond to climate swings and disturbance, especially in places where traditional fossils and pollen records are incomplete. That is a big deal for researchers trying to map resilience.
The Doggerland results underline a point that ecologists often stress, which is that small habitats can matter a lot. A sheltered valley, a south-facing slope, or a wetland edge can function like a life raft for species when the larger region becomes hostile, and the evidence suggests Doggerland played that role in deep time.
The study was published in Proceedings of the National Academy of Sciences.