Ancient DNA shows Ice Age humans targeted female mammoths

By Stephen Beech

Cavemen targeted female mammoths, suggests new research.

Analysis of ancient DNA reveals Ice Age humans preferred to hunt females of the now-extinct giant mammals.

A study of DNA from more than 500 mammoth bones showed that early hunters selectively targeted female woolly mammoths.

The findings of the study, published in the journal Current Biology, show that in contrast to the sex ratio among naturally occurring woolly mammoth remains, large bone accumulations associated with ancient human activity are dominated by females.

Co-senior author David Díez del Molino, of the Centre for Palaeogenetics in Stockholm, Sweden, said: "Whether these massive mammoth bone accumulations were formed naturally or by human hunting has been debated for decades.

"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."

The international research team analyzed genome data from 521 woolly mammoths across Eurasia and North America, including 448 individuals sequenced for the first time.

Genetic sex inference revealed a "striking" contrast depending on where the remains were found.

Mammoth remains recovered from dispersed, natural settings were mostly male (66%), consistent with the idea that solitary males were more likely to die in natural traps, such as sinkholes or landslides, thereby increasing the chance of long-term bone preservation.

In contrast, mammoths from accumulation sites were predominantly female (70%).

The findings raised questions about how Ice Age hunter-gatherers interacted with mammoths.

Jarosław Wilczyński, from the Institute of Systematics and Evolution of Animals at the Polish Academy of Sciences, said: "We know that Upper Paleolithic hunter-gatherers sometimes hunted mammoths directly, as evidenced by projectile points embedded in mammoth bones, and they may also have scavenged material from carcasses."

Study lead author Hannah Moots, also of the Centre for Palaeogenetics, 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.

"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 Paleolithic hunter-gatherers may simply have encountered them more frequently, whether for hunting or scavenging."

The researchers explained that mammoths were a vital resource for Ice Age human populations, providing meat, fat, hide and bones for building structures, and ivory for tools, art, and ornaments.

The mammoth bone accumulations included in the study span 11 key Ice Age archaeological sites across Eurasia, dating to around 20,000 to 30,000 years ago.

By combining 100 individuals from the human-associated site accumulations with 421 mammoths from natural depositional settings, the team analyzed a large dataset of woolly mammoths.

The unprecedented scale provides a rare look at how ancient humans and woolly mammoths interacted.

Study co-senior author Love Dalén, of Stockholm University, said: "This research demonstrates the power of ancient DNA studies to answer long-standing archaeological questions."

He added: "By scaling up sample sizes, ancient DNA can go beyond evolutionary history to teach us about animal behavior and human culture tens of thousands of years ago."

The research team identified one mammoth from Wrangel Island in Russia that was neither XX (biologically female) nor XY (biologically male).

Instead, it had a different sex chromosome combination known as X0/XX mosaicism, where the individual has a single copy of the X chromosome in some cells, and two in others.

In humans, it is known as Turner Syndrome.

It is the first time that the sex chromosome combination has been documented in an extinct species.