Ancient DNA Reveals Prehistoric Forest Beneath North Sea Was Major Ice Age Refuge

Beneath the surface of the North Sea, a long-hidden prehistoric forest has been found, revealing many new possibilities for the environment and climate of ancient Europe. By using sediment collected from ancient sites to collect and analyse ancient DNA (sedaDNA), researchers have shown that there were lush, living forests made up of oak, elm and hazel in a sunken landscape now known as Doggerland, thousands of years before scientists had previously thought possible.

This research suggests that Doggerland was a significant refuge for plants, animals and even early humans during the last Ice Age, and that some parts of this lost environment remained above water longer than researchers anticipated, thus providing more information about how the ecology of the area evolved in the past before all of this eventually became submerged under higher ocean levels.

In a new study in the Proceedings of the National Academy of Sciences (PNAS), researchers have developed an alternative chronology of the forests of northern Europe. Researchers analysed 252 sediment samples collected from 41 marine cores and found DNA of temperate tree species that existed at least 16,000 years ago. In a particularly surprising finding, the researchers also recovered DNA from Pterocarya (the walnut family) species that were thought to have been extirpated from the region 400,000 years ago - indicating that isolated 'microrefugia' permitted some species to persist much longer than had previously been determined.

Doggerland, once thought to merely be an ephemeral landmass, seems likely to instead represent a permanent centre of development that was also a very fertile area. According to the PNAS research findings, the existence of Tilia (lime) trees 2,000 years before the date these trees were first recorded as existing in mainland Britain indicates that locally mild climatic conditions supported more complex ecosystems than previously reported. Researchers believe these wooded areas could have provided early Mesolithic human populations with both food and shelter, and could explain the lack of early human archaeological material in Britain today due to continued submergence beneath the North Sea.

The existence of resilient ecosystems in Europe calls into question the accepted view of forest regrowth throughout Europe following the last Glaciation event. New data from the University of Warwick shows that Doggerland survived significant environmental perturbations (such as the Storegga tsunami (8,150 years ago) and some parts were still habitable as recently as 7,000 years ago. The application of sedaDNA methodology to the discovery of marine sediment cores offers unprecedented detail about the past compared to traditional pollen studies and provides a context for future excavation efforts to identify specific locations of human habitation on these submerged landscapes.