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Dr. Alba Rey-Iglesia and her colleagues conducted a biomolecular analysis of the mammoth bone remains at Kostenki 11-Ia, providing fascinating insights into the enigmatic mammoth bone complexes built during the Ice Age. The study, in Quaternary Environments and Humans, hoped to provide new insights into the site's sex, age distribution, and paleoenvironment.

Circular mammoth bone structures have been recovered across western Russia and the Ukraine. Most have been dated to around ~26,000–14,000 cal BP (calibrated years before present) and are usually found along the Desna/Dnpr river systems.

"The circular mammoth bone structures are from the height of the last Ice Age, a period of intense cold, and are widely considered to have been dwellings for shelter during long, full glacial winter seasons or possibly year-round," explains Dr. Lorenzen, one of the study's researchers.

"They may also have been used for ceremonial purposes. The structures are almost always surrounded by a series of large pits that were perhaps used for storage of food or bone fuel or perhaps rubbish disposal."

However, precisely what they looked like is yet unknown. "The weird thing is that when you see the site and the thousands of bones, it's not easy to picture how they might have been erected in any way, as they are heavy," says Dr. Lorenzen. "The way I've seen them depicted (at the Natural History Museum in Vienna) is as a tent-like structure. But as only the bones are left, no one knows."

Kostenki 11 (Anasovka 2) is an Upper Paleolithic (~35,000–10,000 ya) site near the Kostenki and Borshchevo villages in Russia. The site consists of five layers, which have been radiocarbon dated to between ~40,000 and ~24,000 years BP.

Kostenki 11 was first discovered in 1951. Since then, three mammoth bone complexes have been discovered, and the main building of the Kostenki Museum-Preserve has been erected around the first complex.

The third complex, called Kostenki 11-Ia, is the biggest of the complexes, measuring in at ~ 12 x 10m, and is comprised of at least three peripheral pits. Within the complex are ~2,982 individual mammoth bones, collectively making up at least 64 individuals.

Previous radiocarbon dates indicate the site was likely built around 24,000–25,000 ya. Making Kostenki 11-Ia one of the oldest circular mammoth-bone structures in the eastern European Plain.

All of Kostenki's mammoth bones belong to one of the most well-known mammoth species, the woolly mammoth (Mammuthus primigenius). Due to their rich fossil record and the preservation of several specimens in permafrost, they're among the well-studied Eurasian mammoth species.

It has been hypothesized that these mammals likely had a matriarchal social structure in which an adult female would lead a group of other females and their young. Meanwhile, adult males would leave these groups upon maturing and live alone or form temporary bachelor groups.

The biomolecular work at Kostenki-Ia involved analyzing 39 specimens from the bone complex, combining both morphological and genetic methods to determine sex ratios and familial relationships.

The results indicate that the majority of mammoths (57% were female, while males made up the other 43%. The over-representation of females, compared to other mammoth bone assemblages, and the inclusion of juvenile remains led the researchers to believe that Ice Age humans were primarily targeting mammoth herds or at least scavenging from herd bone-beds rather than trapping solitary male individuals.

The mitochondrial DNA provided additional insights. "The fact that we find multiple mitochondrial lineages present in the individuals—mitochondria are passed on from mother to child, and so they would share the same sequence/lineage—shows that the mammoths are from several herds, and not just one.

"We would expect the same mitochondrial DNA sequence to be present within a herd, as herds comprise mothers and offspring from within the same family."

Finally, one of the more unexpected finds came from the radiocarbon dates. "Several findings were surprising. One was the inclusion of the two older bones," explains Dr. Lorenzen.

Of the nine radiocarbon dates taken, two were several hundred years older. These dates came from a female and a male mammoth and were dated to around 25,662–24,802 and 25,798–25,140 cal BP, respectively.

"The fossil scavenging behavior that we infer from the two much older dates has, to our knowledge, not been reported anywhere else." Lorenzen elaborates on the significance of the finding, saying, "Our findings appear to show the bones were harvested from elsewhere—as in the mammoths did not die on site—and perhaps older (as in long-dead) mammoths were harvested in addition to newly-dead mammoths.

"We don't have evidence to say whether the humans directly hunted the mammoths, and we infer they were likely found in natural bone beds and transported to the site. But perhaps mammoths may have died across many hundreds of years in the bone beds, and thus both old and new were used."

The findings at Kostenki 11-Ia highlight the adaptability and resourcefulness of Upper Paleolithic humans and provide new insights into the sex distributions and age range of mammoth bone used to construct these enigmatic bone complexes.

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