Where people lived when ice covered Europe

27,000 years ago: lights from the Atlantic to the Don#

This is Europe before the deep cold. The lights run from Portugal to the Russian Plain: 122 places have a date within 500 years of this moment. People hunted reindeer, horse and mammoth on cold, open steppe, and their tools look alike from Spain to Russia.

Their genomes still show two populations. Those in France and Spain descended from the first modern humans of western Europe. Those from Moravia to southern Italy belonged to a different branch, related to the hunters of the Russian Plain.

The ice comes south#

Scroll, and six thousand years pass. The Scandinavian ice sheet joins the one over Britain and Ireland and, at its furthest, reaches the ground where Berlin now stands. The Alps disappear under an ice cap of their own.

On the margins mapped by geologists, the ice of northern Europe grows from 3.6 to 5.6 million km², about 10 times the area of France. Over the Gulf of Bothnia, one reconstruction puts it at roughly 2,700 metres thick.

The ice came from cool summers, not hard winters#

Pull back, and Europe’s ice turns out to be one sheet of several: a larger one covered Canada and the ground where Chicago now stands. This ice had been building for a long time. The last warm period ended about 115,000 years ago, and what the globe shows here is the peak of a long cold, not its start.

The pacing comes from the Earth’s own motion. The shape of its orbit, the tilt of its axis and the season in which the Earth passes closest to the Sun all drift, on cycles of about 100,000, 41,000 and 23,000 years; the Serbian mathematician Milutin Milanković worked out the sums in the first half of the last century. When the far north gets weak summer sunshine, the winter’s snow does not all melt, and year on year it piles up into ice. A 2009 study ties both the growth of the ice sheets and the start of their melting in the Northern Hemisphere to the summer sun of the north.

The orbit alone is not enough. White ice sends sunlight back into space, and the air lost carbon dioxide: bubbles trapped in Antarctic ice show about 190 parts per million, against about 280 before industry. A 2020 reconstruction puts the planet as a whole at about 6 °C colder than before industry.

Sea level falls by more than a hundred metres#

So much water was locked in the ice that the average level of the world’s oceans fell to about 134 metres below today’s. Off France, on this map, the sea is about 105 metres below its present level.

The paler ground was land then and is sea floor now; the dashed line is today’s coast. A river runs across the dry floor of the Channel. On the map Britain is joined to the continent, and the northern Adriatic is a plain that runs far beyond Venice.

North of the Alps, the lights go out#

North of the 50th parallel and west of the Oder, every date between 27,600 and 16,500 years ago was checked in the study that published it. Of 90 dates, 33 show that people were there. The others are animal bones with no tool marks, or measurements overturned by newer dating.

What is left: four places at 27,000 years ago and, through the coldest millennia, one light at a time, at most. At Wiesbaden-Igstadt, near the Rhine, dated reindeer and horse bones show that hunters came more than once in the depth of the cold. Otherwise the map between the two ice sheets stays dark.

Half of the lights are in France and Spain#

Of 288 places dated to the coldest four thousand years, 154 are in southern France, Spain and Portugal. Part of that gap is because more has been dug and dated here than anywhere else. The rest comes from the place: the limestone valleys of the Dordogne and the Cantabrian coast had caves, water and herds of reindeer, horse and ibex.

The people here knap flint points as thin as a leaf. The caves of the region, Lascaux and Altamira among them, hold paintings from several periods of the Ice Age.

Italy, the Danube, the Carpathians#

East of the Alps the lights are fewer. Grubgraben above the Austrian Danube, Ságvár near Lake Balaton, the terraces of the Bistrița in the Eastern Carpathians and Paglicci cave in southern Italy all have dates from these millennia.

Less has been excavated here than in the west, so the map shows fewer traces than there were.

On the Russian Plain, people stayed#

The east breaks the rule. Between the Dnieper and the Don, at the latitude of ice-covered Ireland, 23 places north of the 50th parallel have dates from the coldest millennia. Kostenki on the Don and Zaraysk, south of where Moscow now stands, are among them.

The mapped edge of the ice stops far to the north. Mammoths lived on the steppe, and people stayed with them. Later, at Mezhyrich, they built round houses out of mammoth bones.

Two populations went into the cold. Only one is found after it#

Ancient DNA shows who came through. A 2023 study of 356 hunter-gatherer genomes finds the western population in the depth of the cold, at Le Piage in France and La Riera in Spain, and then in its descendants afterwards.

The other population, the one known from Moravia and Italy, has not been found in any later genome analysed from those regions. In Italy, everyone analysed from after the cold belongs to a new group, which the study suggests came in from the Balkans.

The ice pulls back and the lights follow#

From 19,000 years ago the ice sheets shrink: of 5.6 million km², 2.5 million are left 15,000 years ago. The lights move north with the herds, along the Rhine, into the Paris Basin, into Poland.

North of the 50th parallel and west of the Oder, the number of dated places rises from one to 48 (dates after 16,500 years ago were not checked one by one). Their tools and their genomes tie these people to the south-western refuge.

Back in Britain, on foot#

About 15,000 years ago people reach Britain again. At Gough’s Cave, in south-west England, they left butchered horse bones and human skulls shaped into cups.

They needed no boats. The floors of the North Sea and the Channel were still dry land.

14,000 years ago, the heirs of the refuge are replaced#

Then the genomes change again. From at least 14,000 years ago, hunters from France to Poland mostly carry the ancestry of the group that appeared in Italy after the cold. In Spain the older population lasted longest, mixing with the newcomers step by step. The study describes an almost complete replacement and suggests, as a hypothesis, a link with the abrupt warming that began 14,700 years ago.

So the people who came out of the south-western refuge did repopulate the north, and within a few thousand years they were largely replaced by a second wave from the south. In western and central Europe the tools changed little. The population changed almost entirely.

The sea comes back#

The melting ice raises the oceans again. The plain between Britain, the Netherlands and Denmark, which geologists call Doggerland, narrows from one millennium to the next. About 9,000 years ago it breaks up into islands, and the last of them probably disappears some 7,000 years ago.

The lights stop 11,500 years ago because the database ends there, with the end of the Old Stone Age. The people stayed.

Are the Basques the heirs of the refuge?#

The Basque Country lies in the middle of the south-western refuge, and Basque is the only language in western Europe unrelated to the Indo-European family. That is where the idea came from that Basques descend directly from the hunters of the Ice Age.

Their genomes say otherwise. Like all Iberians, Basques descend mostly from farmers who came from Anatolia and from steppe herders, both long after the cold. A 2019 study describes them as a typical Iron Age population that the later mixing of the Iberian Peninsula barely touched.

The hunters’ legacy is there, but it is not specially theirs. A 2014 model puts it at about a third in Basques, much the same as in the French, and at nearly half in Estonians.

Britain: both waves, in two caves#

Britain holds the whole sequence in two caves. A person from Gough’s Cave in Somerset, from about 15,000 years ago, carried the ancestry of the people who came out of the south-western refuge. A person from Kendrick’s Cave in north Wales, from about 13,500 years ago, carried the ancestry of the second wave. That is the finding of a 2022 study of the two.

They lived differently, too. The Gough’s Cave people ate horse, red deer and, at times, each other, and made cups from skulls. The Kendrick’s Cave person ate food from the sea and from rivers, and the cave seems to have been a burial place.

Both groups walked in. Britain was still joined to the continent.