A clone is a cell, group of cells, organ, or a whole organism produced by asexual reproduction whose genetic information is identical to the parent cell or organism. Recently, cloning has become an area of major study as recent developments in technology have brought about the possibility of cloning cells, organs and even whole organisms like animals and human beings. Recent technology has made it possible to isolate and make copies of individual genes that direct an organism's devleopment.
The first successful cloning of mammals was achieved in 1984 when scientists both in Switzerland and the United States successfully cloned mice. Twelve years later, a whole sheep was cloned. It was named "Dolly" and it lived 7 healthy years before it was put to death by lethal injection because of lung cancer and crippling arthritis. However, this cloned sheep aroused the interest of scientists worldwide. It also sparked controversy due to the ethical issues related to cloning. If a sheep identical to its mother could be created, why not a human being?
Science took a giant leap towards this possibility of human cloning in 1993 when the first human embryos were cloned. The embryos were fertilized in test tubes in a laboratory which could then be implanted into the wombs of women having difficulty becoming pregnant. However, none of these fertilized eggs successfully developed to a stage that was suitable for transplantation into a human uterus.
It is important to know however that there is not only one type of cloning. When the media report on cloning in the news, they are usually talking about only one type called reproductive cloning. There are different types of cloning however, and cloning technologies can be used for other purposes besides producing the genetic twin of another organism. On this website, three different types of cloning are discussed: