Sequence and rewind: Scientists are racing to clone the extinct woolly mammoth and other prehistoric beasts, perhaps one day creating a real life 'prehistoric zoo'.

Credit: AFP

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It may seem like science fiction, but it's not. Not even ten years after the first mammal was cloned, scientists are racing to clone the first extinct species.

February 2007 marks 10 years since Scottish scientists announced they had successfully cloned Dolly the sheep. It was a huge accomplishment, and the culmination of decades of research. Now she sits at the top of a long list of clones including cats, pigs, cows, a dog, monkeys, horses and goats.

Perhaps, though, the most significant addition to this ever-growing list was Noah the gaur. The gaur is an endangered, large, dark-coloured ox with a humplike ridge on its back and white or yellow stockings on all four legs - and its numbers are steadily declining.

Noah became the first member of an endangered species to be successfully cloned when he was born in 2001. He was brought to term by a surrogate mother - Bessie, a domestic cow. Unfortunately, Noah died after only two days due to an infection reportedly unrelated to cloning.

The U.S. biotechnology company that cloned Noah, Advanced Cell Technologies (ACT), proclaimed their work as altruistic. "We don't see this as a profit centre for the company," according to Michael West, President of ACT. "Our thought is simply that the human species has casually used technology to despoil the planet, the least we can do is use the technologies we work with every day to make a small contribution to save innocent and endangered species."

Born along with Noah was an intriguing new method of maintaining biodiversity. Approximately 100 species continue to go extinct each day, and governments and conservation groups are fighting to protect the animals endemic to their lands.

The San Diego Zoo, in the U.S., hosts a frozen repository of tissue from 675 endangered species. Twenty-five years ago the Frozen Zoo was filled only with sperm and ovaries. Now it also holds cell-lines and tissue samples from any part of the body.

Using skin cells from the Frozen Zoo, ACT cloned another endangered species in 2003. Two bantengs - another Southeast Asian ox - were created using the same basic method as for Dolly the sheep. The company took DNA from banteng skin cells and put it in the egg of a domestic cow that had already had its DNA removed. What was unique with the banteng was that a member of a different species provided the egg.

Nature has its own frozen zoo. Unlike the youthful San Diego Zoo, in existence for only 25 years, the vast wastelands of Siberia have held animals trapped in permafrost for as long as 200,000 years. This repository hasn't escaped the attention of ambitious scientists.

In 2002 Akira Iritani, from Kinki University in Japan, announced plans for his team to create 'Pleistocene Park' - a home for resurrected woolly mammoths, extinct for approximately 3,500 years. Later additions would include the woolly rhinoceros, which hasn't roamed the Earth for more than 10,000 years.

It is a race against time, partly because climate change is melting the permafrost in Siberia, uncovering ancient animal remains at an increasing rate. Once uncovered, the specimens begin to rot, degrading DNA that may have remained intact for eons.

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