By subdividing their analysis by registered versus anonymous contributors, the researchers found that among those who contribute often, registered users are more reliable. And they discovered that among those who contribute only a little, the anonymous users are more reliable. The researchers were most surprised to find that the reliability of Good Samaritans' contributions were at least as high as that of the more reputable registered users' contributions. "This finding was both novel and unexpected," says Denise Anthony, associate professor of sociology. "In traditional laboratory studies of collective goods, we don't include Good Samaritans, those people who just happen to pass by and contribute, because those carefully designed studies don't allow for outside actors. It took a real-life situation for us to recognize and appreciate the contributions of Good Samaritans to web content."

None of us can know the answers for sure until our own time comes, but the few individuals who have their brush with death interrupted by a last-minute reprieve can offer some intriguing insights. Advances in medical science, too, have led to a better understanding of what goes on as the body gives up the ghost. Whether as a result of a heart attack, drowning or suffocation, for example, people ultimately die because their neurons are deprived of oxygen, leading to cessation of electrical activity in the brain — the modern definition of biological death. If the flow of freshly oxygenated blood to the brain is stopped, through whatever mechanism, people tend to have about 10 seconds before losing consciousness. They may take many more minutes to die, though, with the exact mode of death affecting the subtleties of the final experience. If you can take the grisly details, read on for a brief guide to the many and varied ways death can suddenly strike.