rapamycin was first shown to extend lifespan in eukaryotes in 2006 by powers "et al." who showed a dose-responsive effect of rapamycin on lifespan extension in yeast cells. in a 2009 study, the lifespans of mice fed rapamycin were increased between 28 and 38% from the beginning of treatment, or 9 to 14% in total increased maximum lifespan. of particular note, the treatment began in mice aged 20 months, the equivalent of 60 human years. rapamycin has subsequently been shown to extend mouse lifespan in several separate experiments, and is now being tested for this purpose in nonhuman primates (the marmoset monkey).