Cloning a human

People have been cloning animals but now people?!?!?!?!?!?!?!?!?!

Ever since the birth of Dolly the sheep in 1996, human cloning for reproductive purposes has seemed inevitable. Even with practiced efforts, 25 percent of cloned animals have overt problems such as death and birth defects. The possibility of human cloning may not be restricted to Homo sapiens.

How it will be done

Scientists generate clones by replacing the nucleus of an egg cell with that from another individual. They have cloned human embryos, but none has yet successfully grown past the early stage where they are solid balls of cells known as morulas--the act of transferring the nucleus may disrupt the ability of chromosomes to align properly during cell division. "Whenever you clone a new species, there's a learning curve, and with human it's a serious challenge getting enough good-quality egg cells to learn with," says Robert Lanza of Advanced Cell Technology in Worcester, Mass., who made headlines in 2001 for first cloning human embryos. Especially tricky steps include discovering the correct timing and mix of chemicals to properly reprogram the cell.