This article is out of date; lots of progress has been made since then. The NIH-sponsored Intervention Testing Program showed conclusively and multiple times that rapamycin is able to extend the lifespan of mice about 10%; and more recently the lifespan of macaques was also shown to be extended. It works by fooling your cells into thinking there's no nutrition available, by inhibiting the "MTOR" receptor. It's well known that "dietary restriction" extends lifespan in most life forms. The doses needed are lower than the usual FDA-approved use of rapa for preventing rejection of transplanted kidneys, and bio-hackers have not encountered lots of side effects. Probably the best hope for increasing health-span, which matters more than life span. Since it's in the public domain, there's not much hope for getting large studies done to prove efficacy, but the "Pearl" study recently showed a good safety profile. Also, the Dog Aging project is in progress, enroll to increase the lifespan of your dog (or not, it's double-blind).