Scientists have explored cloning technology for several reasons. Some use cloned animals to study and fight deadly diseases.
Many people, however, strongly oppose cloning animals, no matter what the benefits. In their view, cloning is messing with nature and should be against the law.
What other animals have been cloned?
Many animals have now been cloned, including:
Some cows produce much more milk than others. By cloning these cows, farmers could make milk more quickly and cheaply.
Scientists use special mice to study diseases like cancer. Cloning them could help scientists research how diseases progress.
To develop new medicines for humans, scientists use animals that are as identical as possible. Cloned monkeys could help improve the development of these medicines.
Why clone a sheep?
There's no sheep shortage, but scientists are able to create sheep whose milk contains medicine. If scientists can then clone these special sheep, it may be possible to produce more medicine at a faster rate.
Can cloning bring back extinct dinosaurs?
Cloning anything is tricky. You need very special conditions, and most importantly, you need DNA. In the movie Jurassic Park, a scientist brings extinct dinosaurs back to life by cloning DNA found in ancient dinosaur blood. T. rex, one of the last large dinosaurs to roam the Earth, lived 65 million years ago. We've never found well-preserved DNA this old. And we probably never will.
Photos: Dr. Ian Wilmut and Dolly; Dolly and her birth mother, courtesy of the Roslin Institute; Illustrations: Clay Meyer