A new way to measure how humans age suggests that Latino Americans withstand life’s wear and tear better than non-Latino whites - and that they may have their Native American ancestors to thank for their longer lives. The findings offer some insight into a long-standing demographic mystery: Despite having higher rates of inflammation and such chronic diseases as obesity and diabetes, Latinos in the United States have a longer average lifespan than do non-Latino whites. The research also helps answer questions about why some people die young while others live to old age, and what chronic diseases have to do with aging. To get a handle on some of these thorny issues, UCLA bioinformatician Steve Horvath and his colleagues have been trying to devise a biological clock that measures age more comprehensively than simply counting up birthdays.