Imagine Europe tens of thousands of years ago—thick forests filled with elephants, bison, aurochs, and small groups of humans armed with fire and spears.
A new study reveals that these early people, including both Neanderthals and Mesolithic hunter-gatherers, changed the landscape far more than scientists once thought.
Researchers from Aarhus University and several European institutions used advanced computer simulations to explore how climate, wild animals, fire, and humans shaped Europe’s vegetation during two warm periods in the distant past.
By comparing their results with ancient pollen samples, they discovered that people were already influencing forests and open lands long before agriculture was invented.
“The study paints a new picture of the past,” said Professor Jens-Christian Svenning, a biologist at Aarhus University and one of the study’s authors.
“Climate change, large herbivores, and natural fires couldn’t fully explain what we saw in the pollen data. When we added humans—their fires and hunting—the puzzle finally made sense.”
The team focused on two important time periods.
The first was the Last Interglacial period, around 125,000 to 116,000 years ago, when Neanderthals were the only humans in Europe.
The second was the Early Holocene, about 12,000 to 8,000 years ago, when our own species, Homo sapiens, lived as Mesolithic hunter-gatherers.
During the Last Interglacial, Europe was home to a rich mix of giant animals—elephants, rhinos, bison, aurochs, horses, and deer.
But by the Early Holocene, many of these giants had disappeared, or their numbers had greatly declined. This loss was part of a global trend that followed the spread of Homo sapiens, who hunted large animals wherever they went.
The simulations showed that Mesolithic hunter-gatherers could have influenced nearly half—up to 47%—of Europe’s plant distribution. Neanderthals had a smaller but still measurable effect, shaping about 6% of plant types and 14% of how open or closed the landscape was.
Their impact came from two main sources: the use of fire and the hunting of large animals. By burning trees and shrubs, humans opened up the landscape. By hunting big grazers like bison and elephants, they indirectly encouraged plant overgrowth, leading to denser vegetation in some areas.
“The Neanderthals were capable hunters who even took down giant elephants weighing up to 13 tons,” Svenning said. “Because there were fewer of them, they didn’t wipe out these animals completely. But Homo sapiens, who came later in much larger numbers, had a much stronger effect on both wildlife and the landscape.”
The findings challenge the long-held belief that Europe’s nature was pristine until farming began around 6,000 years ago. Instead, early humans were already shaping ecosystems long before they grew crops or raised livestock.
“The Neanderthals and Mesolithic hunter-gatherers were active co-creators of Europe’s ecosystems,” said lead author Anastasia Nikulina. “Our results show that humans’ influence on nature goes back much further than we used to think.”
The study, published in PLOS One, combined data from ecology, archaeology, geology, and pollen science. It also used a computer model that employed an artificial intelligence algorithm to test many possible scenarios and find the most likely ones.
“This is the first simulation that quantifies how Neanderthals and Mesolithic hunter-gatherers shaped Europe’s landscapes,” Nikulina said. “By combining thousands of years of data from across the continent, we can now see a much clearer picture of how humans, animals, and climate interacted.”
The researchers hope to apply similar methods to other parts of the world, such as the Americas and Australia—places that were never inhabited by earlier humans before Homo sapiens arrived. Comparing these regions could reveal how human arrival alone changed natural landscapes.
While large-scale computer models provide a broad overview, Svenning said that smaller, local studies will still be essential for understanding the details of how early people interacted with their environments.
“Even without farming, humans were already changing the world around them,” he said. “They were not just surviving in nature—they were shaping it.”
