Rewriting the Code of Life

For decades, altering the genetic code of a living organism was a slow, expensive, and unreliable task. That changed dramatically with the arrival of a tool known as CRISPR, which has transformed genetics into one of the most fast-moving fields in modern science. CRISPR is often described as a pair of molecular scissors. Guided by a small strand of genetic material, it can locate a precise sequence within an organism's DNA and cut it at exactly that point. Once the cut is made, scientists can disable a faulty gene or insert a corrected version in its place. Remarkably, the underlying mechanism was borrowed from bacteria, which use it as a defence against invading viruses. The potential applications are extraordinary. Researchers hope to cure inherited diseases, develop crops that resist drought, and eliminate pests that spread illness. Early trials have already restored sight and treated blood disorders that were once considered untreatable. Yet such power raises difficult ethical questions. Editing the genes of an embryo, for instance, would affect not only that individual but every future generation. Where should society draw the line between healing and enhancement? As the technology advances, scientists and the public alike must weigh its breathtaking promise against risks we do not yet fully understand.