Ice Age Hunters May Have Favored Female Woolly Mammoths
For decades, archaeologists have argued over a basic question about some of the Ice Age’s largest bone piles: did they build up from animals that simply died where they fell, or did prehistoric humans create them through hunting and butchery? A sweeping new genetic study points firmly toward human hands, and adds an unexpected twist. The mammoths people left behind were overwhelmingly female.
A Striking Genetic Divide
An international team of researchers analyzed genome data from 521 woolly mammoths across Eurasia and North America, generating new genetic sequences for 448 of them, making it one of the largest mammoth DNA studies completed to date. The findings were published in the journal Current Biology.
The team determined the genetic sex of each mammoth and compared two very different types of sites: natural bone deposits, such as sinkholes and landslides where animals died without human involvement, and archaeological accumulation sites tied to Ice Age human activity, including the well known site of Kraków Spadzista in southern Poland. The contrast was stark. Mammoths recovered from natural settings were mostly male, at roughly 66 percent male to 34 percent female. At sites linked to human activity, the pattern flipped entirely, with about 70 percent of the remains belonging to females and only 30 percent to males.
“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 for Palaeogenetics in Stockholm and co-senior author of the study. “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.”
Why Solitary Males Left More Natural Remains
The male-skewed pattern at natural sites fits with existing ideas about mammoth behavior. Solitary bulls, wandering largely on their own, were more likely to die in natural hazards such as sinkholes or landslides, conditions that also happened to favor long-term preservation of their bones.
“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,” said Jarosław Wilczyński, an archaeologist at the Institute of Systematics and Evolution of Animals of the Polish Academy of Sciences.
Why Females, Specifically?
The more puzzling question is why human activity so consistently involved female mammoths. One tempting explanation is size. Female mammoths were generally smaller than fully grown males, which might have made them easier to bring down. Researchers caution that the real answer is likely more complicated than that.
“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,” said Hannah M. Moots, a postdoctoral researcher at the Centre for Palaeogenetics and lead author of the study. “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. 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.”
Modern elephants offer a useful comparison. Female elephants travel in tight family groups led by older matriarchs, while adult males tend to live more solitary, wide ranging lives. If woolly mammoths followed a similar social structure, female herds moving along predictable seasonal routes would have been easier for hunter-gatherers to locate and track than scattered, unpredictable males.
What Mammoths Meant to Ice Age Life
The stakes of understanding these interactions go well beyond hunting statistics. Mammoths supplied nearly every resource Ice Age communities needed. Meat and fat provided food, hides offered shelter and clothing, bones were used to build dwellings, and ivory became tools, ornaments, and art. The eleven bone accumulation sites included in the study span roughly 30,000 to 20,000 years ago across Eurasia, capturing a long stretch of this relationship between humans and one of the largest animals to roam the Late Pleistocene.
“This research demonstrates the power of ancient DNA studies to answer long-standing archaeological questions,” said Love Dalén, professor in evolutionary genomics at Stockholm University and co-senior author of the study. “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.”
An Unexpected Genetic Discovery
Amid the broader dataset, researchers also identified one mammoth from Wrangel Island whose sex chromosomes did not fit the usual XX or XY pattern. Instead, this individual showed a condition known as X0/XX mosaicism, carrying a single X chromosome in some cells and two in others. In humans, the equivalent condition is known as Turner syndrome. It marks the first time this particular chromosome pattern has been documented in an extinct species.