A Venn diagram illustrating the hazards of synthetic biology. The green circle contains systems able to evolve. Those outside the circle cannot, and present no more hazard than a toxic chemical. The blue circle contains systems that are self-sustaining. Those inside the circle “live” without continuing human intervention; those outside require continuous feeding, and are no more hazardous than a pathogen that dies when released from a laboratory. Systems within the red circle use standard terran molecular biology; those outside do not. The greatest chance for hazard comes from a system that is self-sustaining, uses standard biochemistry, and is capable of evolving, the intersection between the three circles.