Japanese researchers have announced their intention to bring the long extinct woolly mammoth back to life. Using a cloning technique, the Kyoto University team plans to used preserved tissue obtained from a Russian laboratory to create an embryo. Their plan is to remove nuclei from an elephant ovum and replace them with woolly mammoth nuclei. If all goes according to plan, the woolly mammoth will be incubated in the elephant's uterus. The researchers say it will take about five years before they are ready to create their mammoth baby.

What is most unusual about this cloning procedure is its attempt to bring back to life a mammal that died out 65 million years ago.

Discovery.com discussed some of the controversial aspects of cloning a long extinct breed like the woolly mammoth. Temperament and diet are two concerns as are its potential need for internal bio-organisms that may have gone extinct themselves.

The success of any cloning endeavor is far from certain. For every animal successfully cloned there are myriad failures. According to Reproduction, the success rate for nuclear transfers in mammals is less than 0.1 to 5 percent. The practical effect of that statistic? It requires 20 to 1,000 nuclear transfers to create one viable offspring.