Two fertility scientists have announced plans to create the first human clone within two years, despite new evidence that cloning can produce monstrous results.
Scientists say that creating healthy copies through cloning is harder than they had expected. Clones often have severe problems, such as developmental delays, heart defects and malfunctioning immune systems. In one example that sounds like science fiction, some cloned mice that had seemed normal suddenly grew grotesquely fat as young adults.
It?s not that one particular thing goes wrong, researchers say. Rather, the cloning process seems to create random errors that can produce a number of unpredictable problems, at any time in life. Fewer than 3% of cloning efforts succeed.