For 20,000 years, the bones from dozens of mammoths have held together in a large structure constructed by ancient humans during the European Ice Age. Now, archaeologists digging below the Earth’s surface are illuminating the lifestyles of our ancient relatives during times of scarcity.

Kostenki 11 is a well-known archaeological site located about 500 kilometers (310 miles) south of Moscow. Here, archaeologists with the University of Exeter unveiled a 9-by-9-meter (30-foot) circular feature constructed almost entirely of large mammoth bones used to house ancient people during the last ice age, which began in northern Europe around 75,000 years ago and ended around 18,000 years ago. Climate reconstructions of the time suggest that summers in the region were short and cool while winters were long and cold, often seeing temperatures of -20°C (-4°F) and colder.

To combat the harsh environment, early humans constructed dwellings from bones sourced from animal graveyards. At the Kostenki 11 site, a total of 51 lower jaws and 64 individual skulls were used to line the walls of the structure and then scattered across the interior. Researchers also found bones from reindeer, horse, bear, wolf, and horses as well as red and arctic foxes. The research is published in the journal Antiquity. Within the structure were also the remains of charred wood and other soft, non-woody plants, which suggests that people were burning both wood and bones for fuel and foraging plants to use for poisons, medicines, string, and fabric. The additional discovery of more than 50 charred seeds suggests that the human inhabitants were likely cooking plants, meaning that they had learned to find edible plants even in the face of extreme scarcity. Nearby, hundreds of tiny stone and flint chips were found, which were likely used for hunting and butchering animals.

The mammoth bone structure was covered by less than a meter (1 foot) of sediment. Alex Pryor

Altogether, the site represents a “rare example of Palaeolithic hunter-gatherers living in a harsh environment” where survival was difficult and resources scarce. Many groups of ancient people left the region when temperatures plummeted, creating large bone structures along the way to warmer climates. But what might have set Kostenki 11 apart from other potential stops?

“One possibility is that the mammoths and humans could have come to the area on masse because it had a natural spring that would have provided unfrozen liquid water throughout the winter – rare in this period of extreme cold,” said study lead Dr Alexander Pryor in a statement.

There are around 70 known similar structures in Ukraine and the west Russian plane, but Kostenki 11 is likely one of the oldest features in the region.

"These finds shed new light on the purpose of these mysterious sites. Archaeology is showing us more about how our ancestors survived in this desperately cold and hostile environment at the climax of the last ice age,” said Pryor. “Most other places at similar latitudes in Europe had been abandoned by this time, but these groups had managed to adapt to find food, shelter and water."

Researchers also found bones from reindeer, horse, bear, wolf, and horses as well as red and arctic foxes. Alex Pryor