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Subscribe to RSSScientists have long debated whether climate change or human hunters doomed woolly mammoths to extinction about 10,000 years ago. A new study suggests that delayed weaning due to the prolonged winter darkness north of the Arctic Circle may also be to blame.
The finding, based on an analysis of woolly mammoth teeth from Old Crow in the Yukon, shows that woolly mammoths didn't begin eating plants and other solid foods before the age of 2 and, in some cases, 3. This is much later than customary for modern-day elephants in Africa, according to Jessica Metcalfe, a doctoral student in earth sciences at the University of Western Ontario.
"In modern Africa, lions can hunt baby elephants but not adults. They can’t kill adults. But they can kill babies, and by and large, they tend to be successful when they hunt at night because they have adapted night vision,” Metcalfe explained in a media statement. "In Old Crow, where you have long, long hours of darkness, the infants are going to be more vulnerable, so the mothers nursed longer to keep them close."
She believes this prolonged weaning may have added to the pressures that doomed the woolly mammoths to extinction.
"Today, a leading cause of infant elephant deaths in Myanmar is insufficient maternal milk production," she said. "Woolly mammoths may have been more vulnerable to the effects of climate change and human hunting than modern elephants not only because of their harsher environment, but also because of the metabolic demands of lactation and prolonged nursing, especially during the longer winter months."
Metcalfe, who explains her tooth analysis research in the video above, published the findings in the journal Palaeogeography, Palaeoclimatology, Palaeoecology. Check out the stories below for more information on the woolly mammoth.
- Mammoth DNA could spark resurrection
- Woolly mammoth hair yields fantastic DNA
- Humans drove mammoths to their doom
- Climate change wiped out mammoths
John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).
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Mammoths lived in Asia, Europe, and in N America and at least as far south as what is now Virginia. This story by John Roach is too limited in scope because it only studies mammoths above the arctic circle.
If I'm not mistaken, as the glaciers retreated, mammoths -- cold-loving animals -- followed them north. I recall reading that the last mammoths to survive were a miniaturized subspecies trapped on an arctic island.
Where humans couldn't get at them.
The mammoths near the arctic circle were among the last to go extinct, the Comumbian and other species having vanished a few thousand years earlier. I think Ms Metcalfe is only suggesting that the long nursing times might just be a contributing factor. Another recent study suggests that Mammoths had little genetic diversity (one male fathering many offspring) which also may have played a part. Still, since mammoths were among the last of the ice age megafauna to go extinct, maybe retreating to the arctic circle (and remote islands) may have actually bought it some time.
BBC earth series has documented a lion pack succesfully bringing down, killing and eating a bull elephant. it is specialized behavior in lions, but it is possible.
I'm not sure that prolonged darkness necessarily leads to more nursing. Couldn't we see if that's true with a modern day Arctic mammal like a walrus or something. Also, during those long, cold winter nights I would imagine that most large predators would be in hibernation.