In 2014, Joon Yun, founder of the Palo Alto Institute in California, announced the $1 million Palo Alto Longevity Prize. Its goal: to "hack the code" of aging.

The first half will go to the first group to restore homeostatic capacity—the body's ability to stabilize after experiencing stress. "Until midlife, it is so pervasively effective that we don't realize we have homeostatic capacity until we start losing it," Yun says.

The hitch is, no one knows how to measure it, and so the prize will use proxies such as heart-rate variability, and award whichever team can get an aging animal's heart pumping like it's young again. The other half of the prize will go to the first group that's able to extend the life of a mammal by 50 percent.