|CLONING A MAMMOTH|
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CLONING A MAMMOTH
BY JIM WILSON
After dinosaurs, woolly mammoths are probably the best known extinct animals. We're familiar with these curved-tusk beasts because our cave-dwelling ancestors liked drawing them on their walls. We also have enough bits and pieces to prevent our imaginations from running amok. And soon we could have even more. If an ambitious effort to recover genetic material from a frozen Siberian mammoth fulfills its backers' wildest dreams, a living, breathing and perhaps even breeding woolly mammoth could be the star attraction at your favorite zoo.
Three years ago, French explorer Bernard Buigues spotted what turned out to be a mammoth tusk poking up from the frozen soil along the Bolchaya Balakhnya River in Siberia. He named it Jarkov after the family whose 9-year-old had found it several months earlier. When its teeth were carbon dated they were found to be connected to a 47-year-old animal that had died 20,000 years before.
Last fall, a multinational team of jackhammer-toting scientists led by Buigues successfully chiseled out a 23,000-pound block of permafrost containing the mammoth. With the help of a Russian heavy-lift helicopter, they moved it to an ice cave where it remains preserved.
If the mammoth meat--a term scientists would never use--is as fresh as hoped, it may be possible to extract enough undamaged genetic material to
create a living relative of an animal that has been extinct for 10,000 years.
Cursory genetic examinations suggest the Jarkov mammoth is male. "There's a chance we could get a sample of frozen sperm," says Northern Arizona University paleontologist Larry Agenbroad, a scientist working on the expedition.
Like the sperm of any other warmblooded male, mammoth sperm contains only half the genes needed to create an offspring. This is not a problem. DNA analysis performed on Baby Dima, a mammoth found in 1977, suggests that the Jarkov mammoth might be sufficiently close to the Asian elephant for recovered sperm to fertilize an elephant egg. The offspring of this more or less standard artificial fertilization procedure wouldn't be a mammoth. However, over time selective breeding could wring out all the "elephant" traits, producing a mammoth.
If sperm is unavailable, the explorers would attempt to bring back cells with healthy DNA. Using the technique Ian Wilmut, of Scotland's Roslin Institute, developed to create Dolly the woolly sheep, it should be possible to produce Milly the woolly mammoth.
Genetic engineers believe that the cloning side of the operation, while difficult, would not be impossible. Since Dolly was introduced to a global television audience a few years ago, genetic engineers around the world have been making steady progress toward perfecting the art of cloning replicas of adult animals. Drug companies are driving this research. Their plan is to genetically modify one animal to produce, say, a cancer-fighting drug in its milk. Then, they hope to use cloning to produce an entire herd of genetically identical "twins" (see "Natural Born Factories," March 1998, page 66).
Despite progress since then (mice and possibly goats have been cloned), not everyone is confident ancient DNA could be used to create a new mammoth. "While we can now retrieve snippets of any gene, that does not mean we can put together the genome into organized chromosomes in a nuclear membrane with all the functional apparatus needed for life," cautions Alex D. Greenwood, a researcher at the American Museum of Natural History in New York City. He recently led the team that recovered DNA from animals dead for nearly 33,000 years. Greenwood points out that the warming which revealed the mammoth may have caused serious tissue decay.
Even if scientists fail to inseminate an elephant with mammoth sperm or clone a woolly mammoth from recovered DNA, the Jarkov carcass appears to be so
well preserved that there is a considerable amount of knowledge to be gained from a careful examination. Its blood would help pin the tail on the mammoth's family tree. Even without DNA analysis, looking at the structure of a dried splotch of blood can identify the species. Police forensic labs do this sort of work all the time when, for example, they need to determine if a blood smear on the fender of a car is evidence of a crime, or unintentional four-wheel deer hunting. It was just this sort of analysis that told scientists that Baby Dima was more closely related to Asian than to African elephants.
Perhaps the most important question is why woolly mammoths suddenly became extinct 10,000 years ago. There are two schools of thought. For years, mammoths were believed to have been simply hunted to extinction, like passenger pigeons and--but for a last-minute pang of conservationist conscience--the bison. A newer theory proposes that mammoths were struck down by some sort of virus. The hair on this mammoth might help settle this question. Hair is nature's own fly strip. It collects small amounts of almost everything in the air. The pollen on the hair would tell today's scientists if there were any microscopic critters or viruses that caused this mighty creature to disappear from the face of the Earth in the blink of an eye. If the virus theory is indeed correct, it might be useful for us to know how, and more importantly why, it eradicated a fellow warmblooded animal.