Twenty to thirty millennia ago, ancient human hunters and scavengers targeted mostly female mammoths, analysis of DNA from hundreds of fossils has revealed. 聽
鈥淭he people weren鈥檛 just fooling around 鈥� they knew what they were doing,鈥� says at the Centre for Palaeogenetics in Stockholm, Sweden. 鈥淭hey probably had a structured way to interact with mammoths, one that we cannot really understand.鈥�
Many Palaeolithic archaeological sites include remains from dozens or even hundreds of woolly mammoths (Mammuthus primigenius), generally close to evidence of ancient human cooking. In some cases, scientists have found cut marks, unhealed bone fractures and embedded stone points in the mammoth bones.
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Researchers have debated how much those sites differ from other places mammoths have been discovered, where the position of bones, tusks and teeth suggests the animals died naturally, perhaps caught in sinkholes, landslides or tar pits.
鈥淚t鈥檚 been suggested in the past that these were natural accumulations of skeletons, and that people deliberately set up camp next to such accumulations in order to collect bones, ivory and maybe meat,鈥� says at the University of Bordeaux in France, who wasn鈥檛 involved in the research.
D铆ez del Molino and his colleagues sequenced specimens from 448 mammoths 鈥� mostly teeth 鈥� and analysed previously sequenced DNA data from another 73 mammoths found across Eurasia and North America to determine the genetic sex of 521 ancient animals. Combined, their dataset represented DNA from 100 mammoths at 11 human-related sites from 20,000 to 30,000 years ago, and 421 mammoths from natural accumulations, all across Eurasia and North America.
In the natural settings, male mammoths represented 67 per cent of the specimens. If they behaved like male elephants, they would have often roamed alone and more easily fallen into natural traps 鈥� a trend seen among male bison and brown bears, says D铆ez del Molino.
By contrast, 70 per cent of the mammoths in the human-related sites were female 鈥� suggesting people specifically targeted females. That might have been intentional, since females would have been smaller and, if accompanied by a calf, slower. But it is also possible that hunters were simply taking advantage of herds made up of adult females and their young, says , also at the Centre for Palaeogenetics.
鈥淓lephant herds move in a very predictable way, along seasonal routes, whereas males move more randomly,鈥� she says. 鈥淪o, if that鈥檚 true for mammoths, too, then these ice age sites might have been placed along mammoth migration routes. If the mammoth is really important to you 鈥� and they were 鈥� then maybe you鈥檇 want to make sure you鈥檙e somewhere where you鈥檙e sure mammoth herds will come through.鈥�
鈥淢y reaction to this paper is, 鈥榃ow! This is amazing!鈥欌�� says Pat Shipman, a retired anthropologist. 鈥淚t never occurred to me that female mammoths were preferentially targeted, but if their behaviour is similar to that of living elephants, this pattern makes perfect sense. Female elephants make up the majority of herds and are protective of their babies, so will shield the babies with their bodies, making mothers easier to kill.鈥�
鈥淚n several ways, female mammoths were the path of least resistance for Palaeolithic hunters,鈥� says at the University of Alaska Fairbanks.
Surprisingly, Moots, D铆ez del Molino and their colleagues also discovered one mammoth with XX/X0 mosaicism, a condition in which some cells have only one sex chromosome, which is the genetic basis of Turner鈥檚 syndrome in humans. It is the first ever discovery of a sex chromosome mutation in an extinct species. The condition has been detected in modern domestic animals, but not yet in elephants.
鈥淚 was amazed,鈥� says at the German Archaeological Institute in Berlin. 鈥淏ut of course, we鈥檙e all mammals. So why wouldn鈥檛 they have genetic mutations like we do?鈥�
While the findings are interesting, they paint a tragic picture, says Rowe. 鈥淭he elephant in the room, so to speak, is a new line of evidence that humans contributed to the extinction of mammoths,鈥� she says. 鈥淪adly, they probably didn鈥檛 realise they were contributing to the thinning of their own resources over time.鈥�
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