A post at Fight Aging! will give you the background on new and interesting research into longevity, metabolism and the Sir2 gene in yeast, but you'll find more at the Guardian: "When you do this genetic manipulation, you can get some of the longest lifespans [in yeast] ever described. We have good reason to believe this genetic effect is conserved in other organisms. We're working with mice and human cells now and are already starting to see the same response. ... When you start increasing lifespan by five or six times, it means you're really playing with the life and death programmes of organisms. We're telling the organisms to go into a completely different mode of slow ageing. What they're doing is saying 'I cannot afford to age. I still have to generate offspring, but I don't have enough food to do it now.'"