What’s the story with . . . the woolly mammoth?
JENNIFER CUNNINGHAM July 14 2007 (1)Nothing is more certain than that our comfortable certainties about the past are not set in stone. A baby mammoth discovered perfectly preserved in the permafrost of north-west Siberia has raised the prospect of the creatures, which disappeared 12,000 years ago at the end of the last ice age, being reintroduced by cloning DNA from the female calf.
The six-month-old specimen of mammuthus primigenius was discovered by a reindeer herder, Yuri Khudi, in May on the Yamal peninsula and has been named Lyuba after his wife. Lyuba is the biggest thing in palaeontology for years and caused a buzz at last month's international mammoth conference in Yakutsk in north-east Russia, an area so rich in mammoth finds that it boasts a permafrost museum.
The new find, described by Alexei Tikhonov of the Zoological Institute at the Russian Academy of Sciences in St Petersburg, "as the world's most valuable discovery", because of its state of preservation, has prompted speculation that its hair could provide DNA. That in turn could lead to a mammoth being cloned by fusing the nucleus of a mammoth cell with a modern elephant egg cell stripped of its own DNA.
advertisementDr Ian Barnes, of Royal Holloway, University of London, has said that he believes the discovery of Lyuba could make it possible to clone a mammoth in his lifetime.
The prospect of beasts 9ft tall and weighing three tons walking the earth once more - 10,000 years after their most recent ancestors - is highly controversial, not least because their natural habitat of low-quality grass disappeared as a result of global warming.
Whether that was the fatal blow for the mammoth, the earliest fossils of which date from five million years ago, is one of the hot topics exercising the palaeontologists and palaeobiologists. Opinion tends to divide between scientists and archaeologists. Scientists have traditionally favoured the "overkill theory" which explains the extinction of the mammoths by the arrival of human hunters: the animals, unfamiliar with the danger, failed to defend themselves or escape. Archaeologists, however, think that global warming at the end of the Pleistocene era is the more likely cause, because of the lack of archaeological evidence that humans were killing large numbers of mammoths and horses.
Last year a report in Nature by palaeoecologist R Dale Guthrie of the University of Alaska at Fairbanks suggested that the climatic thaw that allowed humans to cross the land bridge from Asia also caused a radical change to vegetation in the arid Alaska-Yukon region, resulting in rich grass and trees that mammoths (and indigenous horses, sabre-toothed cats, mastodons and giant sloths) could not eat.
Guthrie acknowledges that it is complex, because the arrival of humans and the climate changes were happening simultaneously. However, it becomes even more complex. Last month, a new theory that inbreeding caused the extinction of the mammoth emerged from new genetic analysis carried out by palaeontologists in London on DNA samples from bone, tooth and ivory specimens from Alaska and Siberia. The animals had migrated over the land bridge connecting Siberia and Alaska in what is now the Bering Strait, but with rising sea levels the two groups were isolated and became genetically distinct. By the time the landbridge reappeared 100,000 years ago, the Siberian lineage had died out, reducing the viability of the remaining population.
Then there's the comet theory. Research as yet unpublished claims to have found that multiple fragments of a comet which exploded over Canada nearly 13,000 years ago ignited wildfires across North America which would have killed anything in their path and destroyed food for survivors.
Allen West, the retired geophysicist who is a leader of the research team, says the comet theory is not incompatible with the others: "It seems like there was a perfect storm going on - of overkill, the comet, climate change, possibly disease. I don't think this theory negates any of the other theories. It's just one more of a mix of things that was absolutely lethal to these animals."
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