Dec. 21, 2010 at 5:18 PM ET
Scientists 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.
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).