Ponce de Leon famously scoured Florida searching for the fountain of youth, but he was just one of hundreds throughout history looking for magical waters to create enduring youth. Apparently all these explorers were looking in the wrong place.
Eternal youth doesn't come from water, but instead it's in the dirt—specifically the soil of Easter Island. About 40 years ago, researchers found a compound in the dirt, known as rapamycin, which has been used as an immunosuppressant for transplant patients. In a paper in Nature titled "Rapamycin fed late in life extends lifespan in genetically heterogeneous mice," researchers theorized that rapamycin could increase humans' lives by a few years. During this study, the scientists gave the rapamycin to mice, starting when they were 20 months old (the equivalent of a 60-year-old human). They felt the mice might be too old for the drug to affect lifespan. But they were surprised to learn it increased the lifespan of the rodents by 28 to 38 percent. It also works as an appetite suppressant—doctors who study aging agree that decreased calorie intake and genetic manipulation increases lifespan.
Rapamycin works on the cellular protein mTOR, which controls cells' metabolisms and responses to stress. The downside is that it lowers immune function, meaning users would be more likely to die from opportunistic infections such as flu or staph infection. Experts say that people shouldn't clamor for the drug (or eat the soil on Easter Island) yet because it would likely do more damage than good. [Photo courtesy of Flickr User badthing1.]