I'm sure you recall news and discussion - back in late 2005 - of the effects of the klotho gene on longevity in mice: "Those mice proved to have life spans 20 percent or more longer than mice with the ordinary version of the gene ... The upper bound of life span extension in the study was 30% or so, in the same ballpark as the results of calorie restriction." Scientists are presently working on following the biochemical paths to understand how it works: "Klotho gene mutation leads to a syndrome strangely resembling chronic kidney disease patients undergoing dialysis with multiple accelerated age-related disorders ... Conversely, mice overexpressing klotho show an extended existence and a slow aging process through a mechanism that may involve the induction of a state of insulin and oxidant stress resistance. Two molecules are produced by the klotho gene, a membrane bound form and a circulating form. However, their precise biological roles and molecular functions have been only partly deciphered."