During the coldest part of the last ice age, ice sheets and glaciers expanded widely and sea level dropped far below modern levels. Across much of northern and central Europe, conditions were too cold and dry for regular human settlement. These pressures set the stage for populations to persist mainly in milder southern regions (refugia) and later expand outward as climates improved.
As ice covered the north, groups survived in "refugia"—areas where climate and resources stayed relatively less severe. For Europe, this idea is most often linked to southern zones such as Iberia, Italy, and the Balkans, which could support people, plants, and animals through the worst cold. These refugia later became important sources for repopulating newly habitable regions.
After the LGM peak, temperatures gradually rose and ice sheets began to retreat, though the climate remained harsh. This slow shift increased the amount of usable land along the southern edges of the ice and opened travel corridors in some regions. Human groups could start exploring beyond long-occupied refugial zones as ecosystems slowly expanded northward.
Ancient DNA studies indicate that Late Glacial Europeans drew ancestry from more than one long-separated source population. Research finds that some Late Glacial groups in southern Europe show mixtures of lineages often labeled "Goyet Q2" and "Villabruna," suggesting both isolation in refugia and later contact as conditions improved. This helps explain how postglacial recolonization combined movement with population mixing.
By the later ice age, Magdalenian hunter-gatherers were widespread in western Europe and are often associated with northward and eastward expansion during improving conditions. Their tool traditions and long-distance connections helped people use a broader range of landscapes, including areas closer to the former ice margins. This marks an important cultural phase in the repopulation story of post-LGM Europe.
Around 14,700 years before present, the climate warmed rapidly in the Northern Hemisphere during the Bølling–Allerød interstadial. Ice sheets retreated faster, and habitats like open woodlands and productive river valleys expanded. This created new opportunities for people to move into areas that had previously been too cold or unstable to use regularly.
A short cold phase known as the Older Dryas occurred between warmer parts of the Bølling–Allerød. Even brief cooling could shrink forests, reduce key resources, and make higher-latitude living riskier. These climate swings meant recolonization was not a smooth march north, but a stop-and-go process.
During the Allerød, a warmer and wetter phase within the Bølling–Allerød period, environments across much of Europe became more productive. Expanding birch and pine woodland and richer animal communities supported wider and more stable land use. In many regions, this is when Late Upper Paleolithic groups intensified travel and settlement across newly habitable zones.
Around 12,900–11,700 years before present, the Younger Dryas brought a sharp return to colder conditions in the North Atlantic region. In Europe, this likely reduced forest cover in many areas and shifted animal and plant distributions. Human groups that had expanded north had to adapt by changing mobility patterns, hunting targets, and the places they used most intensively.
The Ahrensburgian culture is dated to the Younger Dryas and is associated with mobile hunting in cold, open landscapes of north-central Europe. Reindeer were a major prey species, fitting a tundra-like environment. This shows that even during renewed cold, people maintained (or re-established) northern lifeways rather than abandoning the region entirely.
In the warmer Late Glacial, Hamburgian groups spread across the North European Plain in areas near the retreating ice. They are commonly interpreted as specialized reindeer hunters tracking herds across open landscapes. Their presence signals a clearer human return to northern regions as climates temporarily improved.
At about 11,700 years before present, the Younger Dryas ended and the Holocene began, bringing warmer and generally more stable conditions. Forests expanded widely, and northern landscapes became more predictable for long-term use. This climatic shift marks a clear closing outcome of the postglacial recolonization phase: Europe’s repopulation could consolidate and set the stage for later Mesolithic lifeways.
Last Glacial Maximum refugia and postglacial recolonization of Europe (c. 26,500–10,000 BP)