On trial.

As researchers uncover basic mechanisms that underlie aging, they hope that lessons learned from mice, worms, flies, and other lab denizens will apply to people. Making that leap requires a new set of scientific approaches, from observational studies to the most rigorous of tests, the double-blind, randomized, placebo-controlled clinical trial. Navigating this unique scientific terrain presents new obstacles for basic-science researchers but can provide the ultimate payoff.