Genetic sexing of 521 mammoths found that about 70 percent of individuals at human-associated sites were female, compared with 34 percent at natural sites, pointing to people as the builders of vast bone accumulations.
Across Central and Eastern Europe, archaeologists have found extraordinary concentrations of mammoth bones at sites used by Ice Age people. Some contain the remains of dozens of animals. In places, the bones were even arranged into circular structures that may have served as dwellings. For decades, researchers have argued over how these accumulations formed.
A study published in Current Biology offers a new kind of evidence. By determining the genetic sex of hundreds of mammoths, an international team led by researchers at the Centre for Palaeogenetics in Stockholm found that human-associated sites contained far more females than would be expected from natural deaths.
“Whether these massive mammoth bone accumulations were formed naturally or by human hunting has been debated for decades,” said David Díez-del-Molino, a researcher at the centre. “By comparing the genetic sex ratios of hundreds of mammoths from natural settings with those found in these archaeological contexts, we can now infer that human activity was the primary driver behind these bone accumulations.”
Sexing mammoths by their DNA
Determining the sex of a mammoth from its bones alone is often impossible, particularly when skeletons are incomplete or the animal was young. Ancient DNA offers a solution. In mammals, females carry two X chromosomes and males carry one X and one Y, so the relative amounts of DNA from different chromosomes reveal an individual’s sex.
The team analyzed DNA from 521 woolly mammoths, 448 of them newly sequenced for the study. The sample included 100 individuals from 11 Ice Age sites in Eurasia associated with humans, dating from about 30,000 to 20,000 years ago, and 421 individuals from natural settings, such as permafrost deposits where animals died without human involvement.
The contrast was stark. At the natural sites, 34 percent of the mammoths were female, a male bias that matches earlier genetic studies. Researchers have suggested that male mammoths, like male elephants today, often lived alone or in small groups and took more risks, making them more likely to die in places such as bogs or rivers where their remains were preserved. At the human-associated sites, about 70 percent of the mammoths were female.
The question of how such sites formed has long divided specialists. Some have argued that Ice Age people could not regularly have killed animals as large as adult mammoths and must have relied mostly on collecting bones and tusks from carcasses or natural death sites. Others point to evidence of hunting, including weapon damage on bones, and to the scale of some sites as signs of deliberate, organized effort.
Hunting, scavenging or both
The finding does not say exactly how people obtained the animals. Jarosław Wilczyński, of the Institute of Systematics and Evolution of Animals at the Polish Academy of Sciences, noted that the evidence points to several possibilities.
“We know that Upper Palaeolithic hunter-gatherers sometimes hunted mammoths directly, as evidenced by projectile points embedded in mammoth bones, and they may also have scavenged material from carcasses,” he said. “While it is tempting to assume that hunters would have targeted females because they were smaller than adult males, the reality may have been more complex.”
Female mammoths would not necessarily have been easy prey. The study’s lead author, Hannah Moots, pointed to the social behavior of living elephants, in which females and their young travel in family groups led by an older matriarch.
“If mammoths behaved like modern elephants, females living in matriarchal herds may have had group defences that would have made encounters with herds equally or even more risky,” Moots said. “Another possibility is that female-led herds moved across the landscape in more predictable ways than solitary males, meaning Upper Palaeolithic hunter-gatherers may simply have encountered them more frequently, whether for hunting or scavenging.”
A rare genetic condition
The large data set also turned up a surprise. One mammoth from Wrangel Island, off the coast of northeastern Siberia, showed a mix of cells with one X chromosome and cells with two. This kind of chromosomal mosaicism resembles Turner syndrome in humans, a condition in which some or all cells are missing one copy of the X chromosome.
According to the researchers, it is the first such case identified in an extinct species. Wrangel Island was the last refuge of woolly mammoths, which survived there until about 4,000 years ago, long after they had vanished from the mainland.
The power of scale
The study shows how large ancient-DNA data sets can address questions that are hard to answer from bones and artifacts alone. Archaeologists have used tool marks, bone breakage patterns and the ages of animals to try to understand how mammoth sites formed, but these approaches have often produced ambiguous results.
“This research demonstrates the power of ancient DNA studies to answer long-standing archaeological questions,” said Love Dalén, a professor at the Centre for Palaeogenetics. “By scaling up sample sizes, ancient DNA can go beyond evolutionary history to teach us about animal behaviour and human culture tens of thousands of years ago.”
The findings have limits. The sex ratios show that human sites contained an unusual proportion of females but not whether people killed the animals, collected bones from animals that died naturally, or both. The 11 human-associated sites also span thousands of years and a wide area, and practices may have differed among them.
The study, supported by the European Research Council, the Swedish Research Council and the Knut and Alice Wallenberg Foundation, adds a new dimension to one of the most enduring relationships in prehistory. Mammoths provided Ice Age people with meat, fat, hides and bones for fuel and building. The new results suggest that, whatever methods they used, those people were drawn above all to the females.
Notes
- “Palaeogenomic sex inference of mammoth remains sheds light on the anthropogenic nature of bone accumulations.” Current Biology, 2026. DOI: 10.1016/j.cub.2026.07.023.
- Stockholm University. “Ancient DNA reveals Ice Age humans preferred female mammoths.” EurekAlert!, 30 July 2026. https://www.eurekalert.org/news-releases/1137453.
Love Dalen