Oldest Circular Structure Discovered – and It’s Made of Mammoth Bones

Mysterious bone circle built 25,000 years ago from the remains of at least 60 mammoths seems to have been too big – and smelly – to be a dwelling, archaeologists posit

Ruth Schuster
Ruth Schuster
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25,000-year-old mammoth bone structure,  Kostenki, Russia: 12.5 meters in diameter
25,000-year-old mammoth bone structure, Kostenki, Russia: 12.5 meters in diameterCredit: A.E. Dudin
Ruth Schuster
Ruth Schuster

While glaciers rolled over Eurasia as the Ice Age reached its peak, prehistoric persons in what is today Eastern Europe eschewed fleeing south, possibly because it didn’t occur to them, and built structures against the desperately cold winds from the material they had at hand: mammoth bones.

Now archaeologists are reporting the discovery of the oldest and biggest of the roughly 70 circular structures made of woolly mammoth bones that’s ever found in Eastern Europe. Measuring over 12.5 meters in diameter and dating to about 25,000 years ago, this third such structure, unearthed in Kostenki, Russia, is so huge that no less than 60 mammoths were used to build it, an international team of archaeologists report in the journal Antiquity on Monday.

“Mammoth bones are very heavy and building the circular structure represents a huge investment of time and energy by the humans that built this,” lead author Dr. Alexander Pryor of the University of Exeter tells Haaretz.

The other two bone circles found at Kostenki, which is about 500 kilometers south of Moscow, were also large, as the genre goes; one was nine meters in diameter. The massive structures provide yet more possible evidence that prehistoric hunter-gatherer groups were capable of impressively monumental, labor-intensive projects.

The smallest of the bone buildings unearthed elsewhere in Eastern Europe were about four meters in diameter, Pryor says.

The remains of the largest of the bone circles, described in the new article, were found in 2014 and excavated over three years by a team of experts from the University of Exeter, University of Cambridge, Kostenki State Museum Preserve, University of Colorado Boulder and the University of Southampton, which is now publicizing the results of its analysis.

Aerial view of the new mammoth-bone structure at Kostenki, taken using a drone during excavations in 2015
Aerial view of the new mammoth-bone structure at Kostenki, taken using a drone during excavations in 2015 Credit: Photograph by A. Yu. Pustovalov & A.M. Rodionov, image prepared by A.J.E. Pryor

At 25,000 years of age, the newly found structure is apparently about 1,000 years older than similar mammoth-bone circles found by archaeologists in Eastern Europe. Pryor does point out, however, that the dating on the other two discovered at Kostenki has not been nailed down yet, and there is another one dating back more than 44,000 years in Molodova, Ukraine, believed to have been made by Neanderthals.

Just to be clear, Ice Age Europeans were not the ones to invent non-cave shelters: The first such dwellings began to appear in Europe around 400,000 years ago.

There's nothing like home 

So why were the Paleolithic persons going to all this trouble? Were these bone circles homes, or did they serve some other purpose?

Archaeologists believe that the mammoth-bone structures were built during a period beginning about 25,000 years ago (or 44,000 years ago if we count the Neanderthals) and ending about 12,000 years ago; the mammoth went extinct in that vast region about 10,000 years ago.

The team did not find evidence of intense habitation in the new structure, though there were traces of fire and food. Maybe, rather like in our day, they carried out rituals involving eating at special sites.

Baby mammoth found frozen in Siberia, 2014, Natural History Museum, London
Baby mammoth found frozen in Siberia, 2014, Natural History Museum, LondonCredit: Matt Dunham / AP

In fact all the bone shelters found had a hearth at the center, or even more than one – except the one at the latest dig. The archaeologists did detect scattered, burnt sediments throughout, but nothing that could be called a single “fireplace,” Pryor tells Haaretz.

Still, among those charred particles they found the first evidence of wood being burned inside a structure made of bone – along with remains of bones that apparently had been burned as well, he says.

While bone was definitely used as a fuel, there is virtually no evidence of burning wood at the other sites.

“This has led to the widespread perception previously that the climate was too cold for trees and bone was used as a replacement fuel because there was no other choice,” Pryor notes.

Indeed, one imagines Eastern Europe at the height of the Ice Age being nothing but ice as far as the eye can see, with the odd prehistoric group clad in furs hunting down a shrieking mammoth. But the mammoth was a herbivore and had to eat too, as did other prehistoric animals; evidently, as Pryor points out, some trees were clearly surviving too – if barely.

“The growth ring widths in the charcoal we recovered are mostly very narrow, suggesting that trees were clinging on at the edge of their tolerance limits. Summers would have been cool and relatively short while winters were long and bitterly cold,” he explains. “The climate was also very arid, so trees would have clung on in sheltered parts of the landscape, perhaps in river valleys, away from the wind and where more moisture was available.”

plan of the third mammoth-bone structure as it
appeared at the end of the 2015 excavation season
Plan of the giant mammoth-bone structure as it appeared at the end of the 2015 excavation seasonCredit: E.M. Ikonnikova & A.E. Dudin

Arguing in favor of Paleolithic settlement, some of the roughly 70 bone circles found to date are isolated but other sites have up to six of them – although work is still being done to check if they were occupied simultaneously. In any case, the discovery of sites with multiple structures of this kind and their abundance of features suggests that they were actually permanent Ice Age settlements, some experts argue: They were proto-villages, typically built in proximity to rivers.

Arguing against such Paleolithic settlement, other evidence suggests seasonal usage of the circular or oval bone structures. Also these “proto-villages” with multiple structures seem to have been rather short term, occupied for a decade or two, not more. Analysis of one such site, Mezhirich in Ukraine, led the team at the time to postulate repeat seasonal occupation, but not permanent settlement.

As for the latest discovery, Pryor doesn’t think the structure served as a home. What it was is another question.

Ice Age ritual hall?

The smallest of huts at other sites were about four meters in diameter, but, “this structure is enormous, almost 13 meters in diameter and it is difficult to imagine how an area this large could have been roofed,” he says, though elaborating that they don’t know, for example, if the structures were conical, with chinks filled in with mud. If they were like teepees, they might not have needed roofing.

And then there’s the smell. “Some of the bones that make up the ring were found in articulation – for example, groups of vertebrae – indicating that at least some of the bones still had cartilage and fat attached when they were added to the pile. This would have been smelly, and would have attracted scavengers, including wolves and foxes, which is not great if this was a dwelling,” Pryor remarks.

Charred materials from Kostenki 11: A) charcoal fragment that is a single growth ring wide; B) most charcoal showed consistently narrow growth rings. In this fragment, average ring width was 0.13mm; C) charcoal fragment with tight ring curvature deriving from the centre of the stem. Based on ring curvature, the stem was at least 6mm in diameter; D) examples of seeds (currently unidentified); E–F) scanning electron microscope images of charcoal fragments lacking
cellular structure, tentatively identified as crushed soft plant tissue (photographs by A.J.E. Pryor).
Charred materials from mammoth-bone structure: A, B, C - charcoal; D, unidentified seeds; E, F, microscope images tentatively identified as tuberCredit: A.J.E. Pryor

Moreover, the latest one evidenced few signs of habitation – for instance, substantially fewer stone tools than were found in other bone circles of a similar age elsewhere.

“This suggests the intensity of activity at the site was lower than might be expected from a dwelling and was a real surprise given the time and effort invested by the people that built the site,” Pryor says.

So, could it have been a sort of prehistoric hall for rituals? Arguably even when worshipping their deity or conducting a ceremony, with winter weather averaging some minus-20 degrees Celsius before the wind factor, a fire would have been handy, so the charcoal isn’t necessarily indicative that a structure served for habitation. The truth is there’s no reason to think these mysterious edifices were events halls except that, as Pryor notes, it’s hard to come up with another practical explanation of why they would work so hard for a place that they didn’t live in.

Unless ... could at least the biggest of these structures been Paleolithic refrigerators? Clearly, by the agricultural age people had discovered storage, based on silos discovered in Israel that go back over 7,000 years. A seperate study suggested that precious marrow was "stored" in elephant bones 400,000 years ago.

Possibly the ancient denizens of the ice were using the robust bone structures as a place to store food too, saving meat and possibly other things too for a snowy day, the archaeologists suggest.

“My position is that some of the smaller structures were very likely houses. But I don’t think the new structure at Kostenki can be for the above-mentioned reasons,” Pryor says. “At Kostenki our research team has now started a second phase of research that will try to shed further light on the activities carried out there, particularly focusing on the role of food storage at the site. If at least some of these mammoths were hunted, this is going to generate a lot of food from each kill. Therefore, preserving and storing that food could be a really significant part of what humans were doing there."

Ash layer in the mammoth-bone 'house'
Ash layer in the mammoth-bone 'house'Credit: A.J.E. Pryor

Finally, where would small groups of hunter-gatherers have come up with such a wealth of mammoth bones? How many could they hunt and eat? Pryor suggests that maybe they scavenged bones from a kind of mammoth graveyard: The most recently found structure was composed of the bones of dozens of them.

“This is a huge number to kill,” Pryor points out. And maybe they did, he says: but it’s worth considering other options too.