Can Humans Be Cloned?
In 1997 a sheep named Dolly made headlines around the world.What was special about Dolly?She
was the first mammal successfully cloned from an adult cell,taken from a ewe's mammary gland.Thus Dolly became a younger"twin"to the sheep from which the cell was taken.Before Dolly,
scientists had for decades cloned animals from embryonic cells.Few thought that it was possible to reprogram a cell from an adult mammal to generate another animal in its exact genetic image.Cloning from an adult cell makes it possible to see in advance what the offspring will be like.
The aim of the scientists who cloned Dolly was to improve farm animals as a valuable source for producing pharmaceuticals secreted in their milk.The report of the scientists' success first appeared in February 1997,in the scientific
magazine Nature,under the title"Viable Offspring Derived From Fetal and Adult Mammalian Cells."The media quickly seized on the report and its implications.Two weeks later the cover of Time magazine featured a photograph of Dolly along with the headline"Will There Ever Be Another You?"That same week,Newsweek magazine ran a cover series entitled"Can We Clone Humans?"
Since Dolly,scientists have cloned dozens of individual animals—all from adult cells.Can the same technology be used to clone adult humans?Yes,say some biologists.Has it been done?Not yet.Ian Wilmut,theBritish scientist who led the team that cloned Dolly,points out that cloning is presently"a very inefficient procedure,"producing a death rate among fetuses that is about ten times higher than in natural reproduction.
Some wonder,'What if someone were to perfect the technique and cloned say,multiple Hitlers?'In an effort to allay such fears,Wilmut points out that while a cloned child would be a genetically identical twin of the person from whom it was cloned,a cloned human would be influenced by its environment and would develop a distinct personality just as natural twins do.