Let there be light
By John Travis
Many scientists suspect that ribonucleic acid, or RNA, preceded DNA and served as life’s first genetic material. Yet it’s never been clear how long strands of RNA, or DNA for that matter, could form in the harsh conditions of the primordial Earth, especially under the intense ultraviolet (UV) light that flooded the planet. Instead of being a barrier to RNA creation, however, UV light might actually have been a help, a new study suggests.
When the planet formed, there was no ozone layer, so the amount of UV light hitting the surface was about 100 times what it is today. Most origin-of-life researchers argue that such a bombardment would destroy fledgling organic molecules unless they were hidden underwater or otherwise protected.