Solving old embryo debates—and starting new ones.

If you can make the seventh and eighth cells become one thing or the other—a baby if placed in Petri Dish A, a bunch of stem cells if placed in Petri Dish B—why can't you do the same to the first cell? Some pro-lifers see this as the next breakthrough. They report that "scientists are already discussing a modified version [of ANT] in which adding the nucleus to the egg would result in a single stem cell, not an embryo." Meanwhile, researchers are studying how to reprogram an adult cell backward—making it capable, like an ES cell, of producing many kinds of tissues instead of just one. Take this technology back far enough, and you'll reprogram the cell all the way to totipotency. Take it forward, and you'll turn a would-be embryo into a skin cell. The stem-cell war will be dead. So will the biological sanctity of human life.