You probably think of the Ice Age as a time of endless cold, towering glaciers, and shaggy mammoths. In many ways, you’d be right. But if you dug a little deeper into the frozen soil of Eastern Europe, you’d find something that tells a different story.

Our ancestors, it turns out, were skilled fire benders. That is, they had mastered fire to a remarkable extent.

A new study published in Geoarchaeology reveals that Ice Age humans crafted hearths in the frozen steppe of Ukraine with such finesse that they achieved temperatures over 600°C. These were deliberate, strategic, and essential strategies.

A fiery mystery

For years, archaeologists puzzled over a strange gap in the Ice Age record. We know Homo sapiens used fire in Europe before and after the Last Glacial Maximum (LGM) — the most frigid part of the Ice Age, between 26,500 and 19,000 years ago. But during that frozen core of time? Almost no fireplaces have been found. It was as if the cold had extinguished all traces of fire.

“We know that fire was widespread before and after this period, but there is little evidence from the height of the Ice Age,” says William Murphree, lead author of the study and geoarchaeologist at the University of Algarve.

The recent excavation at Korman’ 9, a prehistoric site along Ukraine’s Dniester River, is helping to solve that mystery. Researchers uncovered three hearths buried beneath nearly 2.5 meters of loess — ancient windblown silt. Thanks to cutting-edge techniques like micromorphology and color analysis, the team was able to peek into the past with unprecedented clarity.

These weren’t simple campfires. The three hearths varied in size, depth, and thermal power. One hearth, nicknamed CF1, was a flat, open structure, with layers of red, black, and brown sediment stacked like a smoky layer cake. Using digital imaging and sediment analysis, researchers found that the soil beneath CF1 had been heated to at least 600°C — and perhaps even much higher during the original burn.

This wouldn’t have been easy, and it meant that people carefully mastered the art of making fire.

“People perfectly controlled the fire and knew how to use it in different ways, depending on the purpose of the fire,” says Philip R. Nigst, archaeologist at the University of Vienna. Some hearths were built bigger and hotter, perhaps for cooking or tool-making. Others may have been seasonal, tailored for migration cycles.

Even the fuel was selective. Charcoal analysis revealed spruce wood as the dominant fuel source, a logical choice in Ice Age forests. But some bones showed signs of charring at over 600°C. People may have been using bones and fat as a fuel, to get the fire to burn even stronger.

“Some of the animal bones found at the site were burnt in a fire with a temperature of over 650 degrees Celsius. We are currently investigating whether they were used as fuel or just accidentally burned,” explains Marjolein D. Bosch, one of the authors and an zooarchaeologist at the University of Vienna, the Austrian Academy of Sciences and the Natural History Museum Vienna.

A very important ability

Fire isn’t just a convenience. For these early Homo sapiens, it was an essential technology, and one that apparently they wielded with increasing skill.

You might picture making a fire as a “rub sticks make flame” type of activity. But imagine building and maintaining a fire in sub-zero winds, day in day out, with minimal fuel, and when your life depends on it every single day. This required knowledge, planning, and adaptability. Fire allowed humans to cook starchy roots, soften meat, and drive away predators. But it also helped in making tools and in heat-treating stones. Some archaeologists even speculate that fire shaped how humans organized their camps, forming social centers around the hearth.

The hearths at Korman’ 9 prove that Ice Age humans were still building and controlling fire at high temperatures even during the coldest part of the Ice Age, but they may have left traces that were more easily removed.

Solifluction — the slow creep of soil in freeze-thaw cycles — likely erased much of the archaeological record. Delicate ash layers could have been swept away by wind, washed away by meltwater, or mixed by burrowing animals.

“Was most of the evidence destroyed by the ice-age-typical, alternating freezing and thawing of the soil?” asks Murphree. “Or did people not find enough fuel during the Last Glacial Maximum? Did they not use fire, but instead relied on other technological solutions?” adds Nigst.

This study doesn’t solve the mystery. But it shows that early humans were proficient at making strong fires, even in adverse conditions. If there was a way to make fire, they would have made it.