An obscure biological trait seems to predict how long mammals—including humans—can live
Biology runs on all sorts of different clocks. While humans tend to stick around into their 70s, 80s, and even 90s, other mammals don’t live nearly as long. Lifespan doesn’t seem to be correlated with size or location on the evolutionary tree. Rhinos, 20 to 30 times our size, typically last into their 40s; chimpanzees,…