How to edit a human

By Tom Whipple

This story begins nearly four billion years ago, when the Earth was just another rock in just another solar system. In a pool of sludge on that rock, something astonishing happened. A long stringy molecule found a way to copy itself. Similar molecules would later carry the code that would enable life forms to grow, digest, run, breathe, read, launch rockets to the Moon. But for now, that molecule only knew how to do a single, important thing – to reproduce. This was the moment that life emerged.

Since then, as each living organism has multiplied, the codes of life have altered by the tiniest increments generation after generation, stretching across time. Most of these mutations have had little impact. Very, very occasionally, they have been extraordinarily useful. The sum of millions of minuscule modifications over billions of generations has given some organisms the ability to survive in water, land, ice or the desert. They have helped them to beat disease, to be stronger, faster, fly.