In a paper, published in “Science” in May 2005, 25 scientists, led by Woo Suk Hwang of Seoul National University, confirmed that they were able to clone dozens of blastocysts (the clusters of tiny cells that develop into embryos). Blastocysts contain stem cells that can be used to generate replacement tissues and, perhaps, one day, whole organs. The fact that cloned cells are identical to the original cell guarantees that they will not be rejected by the immune system of the recipient.
There are two types of cloning. One involves harvesting stem cells from embryos (“therapeutic cloning”). Stem cells are the biological equivalent of a template or a blueprint. They can develop into any kind of mature functional cell and thus help cure many degenerative and auto-immune diseases.
The other kind of cloning, known as “nuclear transfer”, is much decried in popular culture – and elsewhere – as the harbinger of a Brave, New World. A nucleus from any cell of a donor is embedded in an (either mouse or human) egg whose own nucleus has been removed. The egg can then be coaxed into growing specific kinds of tissues (e.g.,...