How to Edit a Human

Tom Whipple in More Intelligent Life:

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. Across the aeons of biological time, this process has led one particular organism – us – to grow large brains, develop opposable thumbs and communicate complex ideas. We’ve mastered fire, tools, technology. In the great span of evolution, this transformation happened a mere split second ago. Degree by degree we continue to change.

Six years ago a group of those highly evolved organisms worked out how to shrink evolutionary time. Scientists in laboratories on either side of the Atlantic discovered a way to manipulate the blind stumblings of random mutations. Through meticulous trial after trial and not a little fortune, they found a way to edit the code of life – to tweak the information that makes our eyes blue, muscles strong or IQs high. Humans had advanced so far that we were finally able to control our own evolution.

Jennifer Doudna, one of those scientists, was not the first to edit genes or genetically modify an organism. But the tool that her team discovered made a previously painstaking and expensive process simpler and usable by almost anyone. Entire PhDs were once spent changing a single gene to make one mutant mouse for research. The eureka moment came in 2012. Doudna remembers the instant when she realised what she had found. She was in her office high above San Francisco bay and her postgraduate student, Martin Jinek, was at the whiteboard. “It was a beautiful California day. I was looking across and seeing the Golden Gate Bridge,” says Doudna, gesturing towards the window: “The sun was streaming in, Martin was writing at the whiteboard.” Stroke by stroke he began sketching a simplified version of a previously obscure molecular mechanism that bacteria use to fight infection. The device had an ungainly name, CRISPR-Cas9. But realisation now dawned that its function was supremely elegant: it chopped up the DNA of invading viruses. What made that discovery important was that the tool could also be programmed to cut up DNA of any kind. Doudna’s team had worked out how to edit the genome of every living thing – even humans.

More here.