Lost world revealed by human, Neanderthal relics washed up on North Sea beaches

MONSTER, THE NETHERLANDS—On a clear, windy autumn afternoon last October, Willy van Wingerden spent a few free hours before work walking by the sea not far from the Dutch town of Monster. Here, in 2013, the cheerful nurse found her first woolly mammoth tooth. She has since plucked more than 500 ancient artifacts from the broad, windswept beach known as the Zandmotor, or “sand engine.” She has found Neanderthal tools made of river cobbles, bone fishhooks, and human remains thousands of years old. Once, she plucked a tar-covered Neanderthal tool from the water’s edge, earning a co-author credit in the Proceedings of the National Academy of Sciences (PNAS) a few months ago.

“Sun, wind, rain, snow—I’m here 5 or 6 days a week,” she says. “I find something every day, almost.”

Van Wingerden’s favorite beachcombing spot is no ordinary stretch of sand. Nearly half a kilometer wide, the beach is made of material dredged from the sea bottom 13 kilometers offshore and dumped on the existing beach in 2012. It’s a €70 million experimental coastal protection measure, its sands designed to spread over time to shield the Dutch coast from sea-level rise. And the endeavor has made 21 million cubic meters of Stone Age soil accessible to archaeologists.

That soil preserves traces of a lost world. During the last ice age, sea levels were 70 meters lower, and what is now the North Sea between Great Britain and the Netherlands was a rich lowland, home to modern humans, Neanderthals, and even earlier hominins. It all disappeared when glaciers melted and sea level rose about 8500 years ago.

That vast continental shelf has been a blank spot on the map of prehistoric Europe because archaeologists can’t mount traditional excavations underwater. Now, thanks to the Zandmotor and construction work on a harbor extension in nearby Rotterdam, van Wingerden and a dedicated cadre of amateur beachcombers are amassing an impressive collection of artifacts from that vanished landscape. Scientists on both sides of the North Sea are applying precise new methods to date the artifacts and sequence any genetic traces, as well as mapping the sea floor and analyzing sediment cores. The effort is bringing to light the landscape and prehistory of a lost homeland of ancient Europeans.

The finds show that the region was an inviting place in the few thousand years before it vanished, with forests and river valleys rich in game. “It’s not a blank area, it’s not a land bridge, it’s probably one of the best areas for hunter-gatherers in Europe,” says Vincent Gaffney, an archaeologist at the University of Bradford.

The dark, cold waters that now hide the region add to its allure because they preserve organic material for DNA analysis and radiocarbon dating better than on land. And the techniques now being tested to explore the area could aid research on submerged landscapes elsewhere, such as Beringia, the vanished land between Asia and North America inhabited by the first Americans. “It really is a pioneer field and will make a huge difference to our understanding of prehistory,” retired University of York archaeologist Geoff Bailey says.

Clad in a bright yellow windbreaker and blue rubber boots, van Wingerden kept her eyes on the sand as she crunched across razor clamshells and bits of driftwood. To the south, the cranes of Rotterdam harbor—Europe’s largest port—were just visible on the horizon. To the north, oversize kites bobbed in the sky, pulling kitesurfers along far below. “Sometimes things are on dry sand; sometimes they’re near the water,” van Wingerden said of her finds. “There’s really no logic to it.”

Fifty thousand years ago, the landscape looked different. Doggerland—which University of Exeter archaeologist Bryony Coles named in the 1990s after the Dogger Banks, a productive North Sea fishing spot—extended from Amsterdam up to Scotland and southern Norway. The region once encompassed at least 180,000 square kilometers of dry land, four times the size of the Netherlands today (see map, below). But until the Zandmotor was built in 2011, archaeologists had glimpsed only the outlines of Doggerland. Fishermen had dragged up isolated bones, tusks, and stone tools.

In calmer seas, archaeologists might have dived to the sea floor for follow-up searches. But the rough, cold, murky waters of the North Sea, crisscrossed with busy shipping lanes, ruled that out.

“The technology [to explore the sea floor] wasn’t available, nobody knew what might have survived sea-level rise, and it all seemed hopelessly expensive and useless,” Bailey says. Archaeologists were also reluctant to be seen chasing after “lost continents,” he adds, lest they be associated with fringe theories such as Atlantis.

That’s changing fast, thanks in part to beachcombers like van Wingerden. In his office at the National Museum of Antiquities, archaeologist Luc Amkreutz opens his email and scrolls through messages, some just hours old. “This morning a fisherman sent in photos of an elk antler with a shaft hole,” he says, opening an attachment. “It just goes on and on.”

A vanished landscape Over the millennia, Doggerland has been an icy wasteland, verdant valleys and forests, and now the bottom of the cold North Sea. Various kinds of humans have adapted to all these changes, with Homo antecessor, Neanderthals, and H. sapiens likely making use of the land’s bounty at different times.

version="1.0" encoding="utf-8"? UNITED KINGDOM IRELAND GERMANY DENMARK NORWAY SWEDEN North Sea North Atlantic Ocean English Channel Liverpool Cardiff Manchester Birmingham Aberdeen Newcastle Glasgow Edinburgh Shetland islands Orkney islands Hebrides islands Isle of Man Belfast Dublin Cork Galway London Oslo Paris Dogger Bank German Bight Jutland Bank Viking Bank Skagerrak Brussels Hamburg Dortmund Bremen Essen Amsterdam 10,000 Coastlines (years before present) 9000 8000 7000 0 0 200 Km BELGIUM Lines based on current research and data Extrapolation based on bathymetry Original location of artifacts Area in detail 1 2 4 3 5 N o r w e g i a n T r e n c h NETHERLANDS FRANCE Km 1. Large flint core ax, 9000 to 6000 B.C.E. Found in a fisher’s net in the 1980s, this ax was shaped and used by Mesolithic European hunter-gatherers. 2. Barbed bone points, 9000 to 6000 B.C.E. Found in sand and gravel recovered from the Dutch coast, these points likely helped humans bag fish and birds in Doggerland’s rich wetlands. 3. Neanderthal flake with birch tar grip About 50,000 years ago, a Neanderthal used a complex process to make birch tar glue and affix it to the point. 4. Perforated antler ax, 9000 to 6000 B.C.E. This shaft for an ax, crafted by early European hunter- gatherers, dates to the final millennia before Doggerland sank below the North Sea. 5. Neandertal hand ax Found in sediments dredged off the Dutch coast south of Rotterdam, this stone tool may be 250,000 years old. Part of a Neanderthal bone was also found nearby. Approximate extent of ice during the last ice age (70,000 to 20,000 years before present)

Using email and a WhatsApp group with the straightforward name “Stone Age Finds,” Amkreutz and Marcel Niekus, an independent archaeologist, keep in constant contact with amateurs scouring beaches all along the Dutch coast. The archaeologists help identify prehistoric artifacts from photos and get access to dozens of specimens in exchange. “We’re easy to approach, and people can bring us finds,” Amkreutz says.

Other researchers are reaping similar bonanzas. In late 2018, Leiden University Medical Center archaeogeneticist Eveline Altena was part of a research group that invited van Wingerden and other amateurs to an open house, asking them to bring human bones for identification. The response was overwhelming: In a single day, beachcombers brought more than 50 human skeletal fragments, many suitable for dating and DNA analysis. “Now, we’re getting new fragments on a weekly basis,” she says. “I can’t keep up anymore.”

In 2015, van Wingerden found a flint flake with a gob of tar stuck to one end to form a simple handle. Niekus and Amkreutz recognized it as a Neanderthal hand tool at least 50,000 years old. Chemical analysis helped show how Neanderthals used complex methods to process birch bark into tar, as a team including Niekus, Amkreutz, and van Wingerden reported in PNAS.

Archaeologists can’t know exactly where on the sea floor an artifact found on the beach originated, so the context they prize is missing. But because coastal reclamation efforts such as the Zandmotor dredge from specific locations, archaeologists know the artifacts’ sources to within a few kilometers. “There are complete cemeteries being sucked up and sprayed on beaches,” Amkreutz says. “Even though these finds aren’t in their original find spot, they can say something about a huge area.”

Those findings suggest several phases of occupation. Tools and other relics 800,000 years old or more harken back to when this part of Europe was likely occupied by Homo antecessor, an early human thought by many researchers to be an evolutionary dead end. One set of footprints, found in a layer of compressed sand on a beach in the United Kingdom and dated by its geological context, recorded children and adults apparently migrating across a mudflat.

Long cold spells then covered parts of the region in ice. About 100,000 years ago, small, hardy bands of Neanderthals arrived on the trail of megafauna such as mammoths and woolly rhinoceros. Hundreds of tools and a lone skull fragment offer evidence of a population living on the fringes of habitable Europe, resourceful enough to eke out a living in small groups under what Amkreutz calls “extreme” conditions on the edge of glaciers.

Neanderthals died out about 45,000 years ago—about when anatomically modern humans entered Europe. A few flint tools, found among stones dredged from the sea floor to create artificial sea walls for the Rotterdam harbor, suggest H. sapiens may have been active in Doggerland even as early as 40,000 years ago, when it was still an icy steppe. (More conclusive tools have turned up in the United Kingdom and Belgium, on each side of Doggerland.) About 20,000 years ago, a severe cold spell made the entire region too cold to be habitable.

But the end of the last ice age, about 15,000 years ago, brought a brief idyll: Pollen samples, DNA evidence, and fossilized wood fragments recovered from the sea floor suggest a fertile landscape of forests and rivers, with plentiful birds, fish, and mammals. Human remains and finely worked stone, bone, and antler tools suggest modern humans made the most of the area, occupying it even as rising waves transformed large parts into a coastal wetland.

The seafloor bones are filling in the picture of Europe’s genetic past. Studies of ancient and modern DNA indicate that certain groups of hunter-gatherers entered northern Europe from the south and east perhaps about 14,000 years ago, after much of the ice had melted; modern European populations still carry their genetic legacy.

The trove of human bones that amateurs turned over to Altena for sampling promises to add to the picture. Of the bones amassed in June 2019, 90 were well-preserved enough for radiocarbon dating and DNA analysis. Altena and researchers from the Max Planck Institute for the Science of Human History (SHH) in Jena, Germany, identified teeth and bones between 8000 and 10,000 years old, when modern human hunter-gatherers occupied Doggerland. They have started to extract DNA, and so far have recovered it from more than five individuals. “In some ways the context is limited, but we can still do so much more than anyone ever expected,” Altena says.

Drawn from the outer limits of hunter-gatherer expansion in the fringes of Europe at that time, those samples “are fascinating,” says Cosimo Posth, an SHH geneticist. He notes that the DNA could illuminate how these early populations mixed with others in Europe.

Most Doggerland finds have been accidental. A long-term goal is to learn enough about the past landscape so researchers can go to sea and look for sites instead of waiting for evidence to wash ashore. “Until you have reliable maps, you can’t do much,” Gaffney says. “We’re dealing with a completely unexplored country we can’t visit.”

More than 10 years ago, Gaffney set out to do the next-best thing, persuading oil, gas, and wind power companies to pass on data gathered in seismic surveys done to plan offshore oil and gas wells. Initial maps were coarse, but over the past several years, Gaffney and colleagues used €2.5 million in funding from the European Research Council to deploy side-scan sonar and other undersea imaging technologies to make their own maps, in what they call the Europe’s Lost Frontiers project. Maps in hand, the researchers looked for ancient areas suited to human habitation.

More than a decade of work paid off last year when Gaffney and Belgian researchers headed to the Brown Banks, about 50 kilometers off the U.K. coast. Mapping had suggested that between 7000 and 13,000 years ago, the spot was an elevated area 30 kilometers long, overlooking a river.

Researchers aboard the Belgian research vessel Belgica took core samples, scooped up sediment, and made “grabs” with a metal claw. Among the finds were traces of a fossilized forest 32 meters beneath the waves, including tree roots, terrestrial snail shells, and peat—plus a small flint flake and part of a broken flint hammerstone shaped by hunter-gatherers. “We went to the place where we thought [human artifacts] would be and recovered them,” Gaffney says. “That’s a first.”

Putting those maps together with the sheer number of samples emerging from the North Sea, researchers are beginning to answer a question particularly relevant to humanity’s future: What do people do when sea levels rise?

About 8500 years ago, a massive freshwater lake in North America called Lake Agassiz, formed by melting glaciers, drained suddenly into the sea. What had been gradual sea-level rise accelerated, and seas rose a few meters within decades. Doggerland transformed from a temperate, forested plain into an estuarial wetland dotted by drier highlands. Core samples collected along river valleys by the Lost Frontiers team traced the flooding, amounting to a “transect through time,” Gaffney says.

To explore the impact on people, Amkreutz analyzed dozens of human bones dragged up by fishing boats as well as finds plucked off the Zandmotor and other Dutch beaches. He traced the bones to 18 offshore sites around the prehistoric Rhine River estuary and dated them with radiocarbon to a precision of about 100 years; all were about 8500 years old.

He and Niekus then used chemical signatures from collagen preserved in dozens of the bones to analyze what people in Mesolithic Doggerland were eating before and during that transition. As the landscape changed, the diet of its residents did, too, shifting from land animals to freshwater fish. “It shows their flexibility in the face of climate change,” Amkreutz says. “They didn’t leave as sea levels rose; they changed their diet.”

Eventually, that, too, came to an end. On the basis of sediments and computer models, researchers think a tsunami originating off modern-day Norway around 6150 B.C.E. devastated Doggerland with waves at least 10 meters high. Soon the landscape vanished as global sea levels continued to rise.

At his lab at the University of Warwick, Robin Allaby is tracing the changes by searching 60 of the core samples collected by Gaffney and his team for what’s called environmental DNA, shed into water and soil by ancient species. The team scoops up and analyzes all the DNA in a sample, using next-generation sequencing methods that capture millions of DNA fragments, and compares it with libraries of known genomes. “The surprising thing is just how much DNA is still down there,” Allaby says. The results chronicle changes in Doggerland’s ecosystems as seas rose.

In the older, earlier layers, “We can see quite a broad range of DNA that’s clearly terrestrial,” he says. Allaby has picked out terrestrial species, including bears, boars, birds, spiders, and mosquitoes. He has identified plant species, too, including hazel and linden trees and meadow grasses. “It’s obviously a lowland, very fertile and probably more attractive than the British uplands and adjacent Europe,” he says.

Higher up, in the younger core samples, the DNA tells a tale of inexorable transformation. “We can see the rise of an estuarine environment and a slow switch to marine taxa,” Allaby says, as bears and boars give way to sea grasses and fish.

Researchers say the techniques being pioneered or perfected in the North Sea could be applied to far-flung hot spots of human migration, including Beringia and the waters that surround the archipelagos of Oceania. “There are big questions about human dispersal and development which can only be answered by looking at submerged landscapes,” Bailey says. “These same landscapes were probably good places to provide stepping stones into new territory.”

At the end of van Wingerden’s afternoon walk, all she had to show for 2 hours of searching were a few pieces of animal bone and a wide smile. But the next day, her luck turned. Tucked in among a pile of seashells, she found a carefully worked tool with characteristic Neanderthal handiwork, dating back at least 45,000 years: one more piece of a lost landscape, rediscovered.