In this Science Daily release, an unexpected result in worm life span studies is being spun as evidence for oxidative stress not to be important in aging. I believe this is overreaching - it looks much more like a case of one (unexpected) effect that increases life span outweighing the expected effect that decreases life span. These things are never straightforward, however: "For more than 40 years, the prevailing explanation of why we get old has been tied to what is called oxidative stress. This theory postulates that when molecules like free radicals, oxygen ions and peroxides build up in cells, they overwhelm the cells' ability to repair the damage they cause, and the cells age. ... Collectively, these molecules are known as reactive oxygen species, or ROS for short. ... They progressively disabled five genes responsible for producing a group of proteins called superoxide dismutases (SODs), which detoxify one of the main ROS. Earlier studies seemed to show that decreased SOD production shortened an organism's lifespan, but [researchers] did not observe this. In fact, they found quite the opposite. ... It seems that reducing mitochondrial activity by damaging it with ROS will actually make worms live longer."