Extinct Giant Deer Survived Ice Age, Study Says
James Owen in London
for National Geographic News
|October 6, 2004|
Saber-toothed cats, mastodons, giant sloths, woolly rhinos, and many other big, shaggy mammals are widely thought to have died out around the end of the last ice age, some 10,500 years ago.
More recently, however, evidence has emerged that at least two of the spectacular megafauna of the Pleistocene era (1.6 million to 10,000 years ago) clung on until recent times.
In the 1990s mammoth remains found on an island north of Arctic Siberia revealed the animals still roamed a tiny corner of the planet just 3,600 years ago. Tantalizingly, this was almost a thousand years after the first pyramids were built in ancient Egypt.
Now a new study, published tomorrow in the science journal Nature, suggests that another striking mammal, the Irish elk, likewise lived way beyond the last ice age.
The Irish elk is also known as the giant deer (Megaloceros giganteus). Analysis of ancient bones and teeth by scientists based in Britain and Russia show the huge herbivore survived until about 5,000 B.C.more than three millennia later than previously believed.
The research team says this suggests additional factors, besides climate change, probably hastened the giant deer's eventual extinction. The factors could include hunting or habitat destruction by humans.
The Irish elk, so-called because its well-preserved remains are often found in lake sediments under peat bogs in Ireland, first appeared about 400,000 years ago in Europe and central Asia. It stood 7 feet (2.1 meters) at the shoulder. Adult males had massive antlers that spanned 12 feet (3.7 meters) and weighed up to 88 pounds (40 kilos).
Through a combination of radiocarbon dating of skeletal remains and the mapping of locations where the remains were unearthed, the team shows the Irish elk was widespread across Europe before the last "big freeze." The deer's range later contracted to the Ural Mountains, in modern-day Russia, which separate Europe from Asia.
Last Stand in Siberia
The giant deer made its last stand in western Siberia, some 3,000 years after the ice sheets receded, said the study's co-author, Adrian Lister, professor of palaeobiology at University College London, England.
"The eastern foothills of the Urals became very densely forested about 8,000 years ago, which could have pushed them on to the plain," he said. He added that pollen analysis indicates the region then became very dry in response to further climactic change, leading to the loss of important food plants. "In combination with human pressures, this could have finally snuffed them out," Lister said.
Hunting by humans has often been put forward as a contributory cause of extinctions of the Pleistocene megafauna. The team, though, said their new date for the Irish elk's extinction hints at an additional human-made problemhabitat destruction.
Lister said, "We haven't got just hunting 7,000 years agothis was also about the time the first neolithic people settled in the region. They were farmers who would have cleared the land."
The presence of humans may help explain why the Irish elk was unable to tough out the latest of many climatic fluctuationsperiods it had survived in the past.
Meanwhile, Lister cast doubt on another possible explanation for the deer's demisethe male's huge antlers.
Some scientists have suggested this exaggerated featurethe result of females preferring stags with the largest antlers, possibly because they advertised a male's fitnesscontributed to the mammal's downfall. They say such antlers would have been a serious inconvenience in the dense forests that spread northward after the last ice age.
But, Lister said, "That's a hard argument to make, because the deer previously survived perfectly well through wooded interglacials [warmer periods between ice ages]."
He added, however, that the animal may have also suffered from increased competition from other species such as moose, which spread rapidly once the climate warmed.
U.S. scientists from the University of Minnesota say the new study makes it clear that the reasons why so many Ice Age mammals went extinct are far more complex than previously realized.
Writing independently in tomorrow's Nature, biologists John Pastor and Ron Moen state: "The [Irish elk] finding lends weight to the idea that there is no one explanation for the so-called Pleistocene extinctions."
Alongside climate fluctuations and vegetation changes, they say, human activity, competing species, and other ecological pressures need to be taken into account for each animal.
Lister said, "Whereas people have been looking for single blanket explanation to account for all these species going extinct, we're saying you've got a range of species with different ecologies and adaptations."
So while the Irish elk preferred relatively temperate conditions and semi-woodland habitats, the woolly mammoth was adapted to cold temperatures and open tundra.
"Past climate changes would have impacted on those two species differently," Lister added.
And if the mammoth and Irish elk both survived, what of the other shaggy megafauna that supposedly perished during the last ice age? The woolly rhinos and cave bears of Europe and Asia, the saber-toothed cats, the mastodons and giant sloths of North and South Americacould some of these have made it through too?
"It's entirely possible," Lister said. "I think there are all sorts of surprises around the corner."
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