Elon Musk has a talent for making enormous ideas sound like casual errands. Launch a rocket, build a robot, fix traffic, fix the internet… fix aging. Yes, aging. In a post on X in 2023, the Tesla CEO zeroed in on something that's both obvious and deeply weird once you notice it: our bodies age with almost spooky coordination. "The precision of our biological clock across trillions of cells is incredible," he wrote, adding that you never see someone with "an old left arm, but a young right arm."