Investigators at the Stanford University School of Medicine and the Buck Institute for Research on Aging have built an inflammatory-aging clock that's more accurate than the number of candles on your birthday cake in predicting how strong your immune system is, how soon you'll become frail or whether you have unseen cardiovascular problems that could become clinical headaches a few years down the road. In the process, the scientists fingered a bloodborne substance whose abundance may accelerate cardiovascular aging. The story of the clock's creation will be published today (July 12, 2021) in Nature Aging. "Every year, the calendar tells us we're a year older," said David Furman, PhD, the study's senior author. "But not all humans age biologically at the same rate. You see this in the clinic -- some older people are extremely disease-prone, while others are the picture of health."