At the end of the last ice age, about 10,000 years ago, woolly mammoths dwindled to extinction as warming weather diminished their food sources, most scientists believe.
There are believed to be ten million mammoths buried in permanently frozen soil in Siberia. Because of the sparse human population in the region, though, only about a hundred specimens have been discovered, including two dozen complete skeletons. Only a handful of complete carcasses have been found.
In 2002 hunters stumbled across the mammoth now on display in Japan. After a period of relatively warm weather, the head of the beast had been left protruding through the snow and ice cover.
The scientists with the Mammoth Creation Project are hoping to find a mammoth that is sufficiently well preserved in the ice to enable them to extract sperm DNA from the frozen remains.
They will then inject the sperm DNA into a female elephant, the mammoth's modern-day counterpart. By repeating the procedure with offspring, scientists say, they could produce a creature that is 88 percent mammoth within 50 years.
"This is possible with modern technology we already have," said Akira Iritani, who is chairman of the genetic engineering department at Kinki University in Japan and a member of the Mammoth Creation Project.
In 1986 Iritani's lab successfully fertilized rabbit eggs artificially, employing a technique now used in humans. In 1990 his colleague Goto, the Mammoth Creation Project head scientist, pioneered a breeding plan to save a native Japanese cow species by injecting dead sperm cells into mature eggs.
The current challenge, however, is finding viable woolly mammoth DNA. The DNA in mammoth remains found to date has been unusable, damaged by time and climate changes.
"From a geologist's point of view, the preservation of viable sperm is very unlikely, and this is so far confirmed by the poor condition of cells in the mammoth carcasses," said Sher, the Russian paleontologist.
Current Siberian permafrost temperatures are 10 to 18 degrees Fahrenheit (minus 12 to 8 degrees Celsius), which may not be cold enough for DNA survival.
Sperm is not the only possible DNA source, and mammoth-elephant crossbreeding isn't the only potential way to resurrect the woolly mammoth.
An alternative method would be to clone a mammoth from DNA found in mammoth muscles or skin. To do this, however, scientists would need preserved cells with some unbroken strands of DNA.
"There is no evidence this exists, and even if it did, it is very unlikely to be preserved without significant errors having accumulatedprobably leading to birth defects," said Lister, the London paleontologist.
The Japanese scientists, however, are not deterred.
Iritani is planning a summer expedition to Siberia to search for more carcasses.
His team has already picked out a home for living mammoths in northern Siberia. The preserve, dubbed Pleistocene Park, could feature not only mammoths, but also extinct species of deer, woolly rhinoceroses, and even saber-toothed cats, he said.
"This is an extension of my work for the past 20 years in trying to save endangered species," Iritani said.
Other scientists are less enthusiastic about the project.
"Even if the cloning experiment is successful, they are not reconstructing the past but rather creating a new mammoth-like creature," said Anatoly Lozhkin, an Ice Age expert at the Northeast Interdisciplinary Scientific Research Institute in Magadan, Russia.
"Scientists are always able to learn from every experiment, but I am not sure that cloning a mammoth will help us significantly move forward our understanding of the animal or the conditions under which it lived," Lozhkin said.
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