(CN) – Travelers from a different time built perplexing bone circles in the plains of what is now Russia. The exact purpose of these sites remains a mystery, but researchers know they were used as temporary camps for humans trying to survive the harsh landscape of the last ice age.
About 20,000 years ago, these hunter-gatherers living in the harsh climate arranged mammoth bones into camp sites. For the first time, archaeologists have found burnt wood and charred seeds likely used for cooking.
The discovery and characteristics of these bone circles are the subject of a study published on Monday in the journal Antiquity.
The bones were pulled from nearby animal graveyards. Reindeer, horse, bear, wolf, red fox and arctic fox bones were also discovered in small quantities at the Kostenki 11 site, about 310 miles south of Moscow, but the sites were dominated by mammoth skulls and bones.
Archaeologists found 51 lower jaws and 64 individual mammoth skulls in the construction of the 30-square-foot circles.
The last ice age, referred to as the Pleistocene Epoch, chilled the planet from about 2.6 million years ago up until about 11,700 years ago.
The study authors say the bone circle sites and the remnants left behind are more than 20,000 years old, meaning these hunter-gatherers were moving about the region as the climate was at its coldest, with temperatures dropping to minus 68 degrees or colder.
Study authors say they found non-woody plant remains and charred wood at the sites, which means wood along with bones were burned for fuel and the communities who lived on the plains learned how to forage for edible plants during the ice age.
Plant life or vegetation in general was scarce during this epoch due to the cold.
Other uses for plants included crafting poisons, medicines, string and fabric. Archaeologists say charred seeds could have meant plants were grown locally or possibly used for cooking.
Researchers also found tiny stone and flint chips just a few millimeters in size, remnants of stone nodules shaped into sharp tools with distinctive shapes that could be used for butchering animals and scraping hides.
Archaeology postdoctoral fellow Alexander Pryor from the University of Southampton said these Paleolithic hunter-gatherers may have come to these regions of the world along with mammoths because they could find a natural spring that would not have frozen over during the extreme cold.
“These finds shed new light on the purpose of these mysterious sites,” Pryor said in a statement. “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. 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.”
Previous attempts to decipher the mammoth bone circles included a theory that the sites were used as dwellings for many months at a time. But the new study indicates the intensity of activity at the site was less than would be expected from a long-term base camp site.
An email to the study authors for comment was not immediately answered.
Research was also conducted by academics from the University of Exeter, University of Cambridge, Kostenki State Museum Preserve and the University of Colorado Boulder.