I've mentioned hormesis and longevity once or twice: a little stress on a biological organism tends to harden it up and make it live a little longer. This Biogerontology paper provides an example of the process in worms: "Mild hormetic heat treatments early in life can significantly increase the lifespan of the nematode C. elegans. We have examined the effects of heat treatments at different ages and show that treatments early in life cause the largest increases in lifespan. We also find that repeated mild heat treatments throughout life have a larger effect on lifespan compared to a single mild heat treatment early in life. We hypothesize that the magnitude of the hormetic effect is related to the levels of heat shock protein expression." This sort of longevity research is akin to metabolic investigations - interesting, probably somewhat useful, but ultimately nowhere near as helpful as other, more direct avenues of anti-aging research.