There’s an old saying that there are no poisons per se–only toxic doses. Many things that are toxic in large quantities can be harmless, even beneficial, in small ones (which is why the Delaney Clause–the federal mandate requiring products to be banned if they cause cancer in lab mice in any quantities, is absurd). Now, we have another example of it, that may have staggering scientific consequences.

Ultra-violet light is often used to kill micro-organisms, so as a major component of sunlight, it’s always been seen as an impediment to the development of life on a young earth. But now researchers have found that it may, under some circumstances, actually contribute to building organic links, and may have contributed to the early development of replicating systems.