Editing Humanity's Future

To alter the human genome seems a dramatic act, one that places a solemn responsibility on those who would commit it. The genome of our species is, after all, an intimate part of who we are, the core of our biology, a repository of the many millions of years of evolution that have yielded the powerful, perverse creature that is a human being. And yet we do something rather like this when we choose a mate. The raw material for evolution, the stuff with which natural selection can play, is genomic variation, and a main source of this variation is…