Irradiated For Longevity
ScienceDaily reports on experiments suggesting that low levels of radiation exposure increase longevity - in small mammals at least. This isn't of immediate practical value, but it adds to the body of knowledge surrounding hormesis, or the "phenomenon in which low doses of an otherwise harmful agent can result in stimulatory or beneficial effects." This study does suggest an underlying biochemical mechanism: "a moderate increase in glucocorticoid levels, associated with low-level radiation, could be an important factor underlying the increase in longevity that has been observed in other shorter studies on small mammals exposed to low-level radiation."
Link: http://www.sciencedaily.com/releases/2005/01/050128222047.htm