French geriatrician Bruno Vellas argues that a 70-year-old today has an intrinsic capacity similar to that of a 60-year-old two decades ago. He wants biological age measured early, so doctors can intervene before health problems take hold. Health systems, in his view, should move away from treating diseases one at a time and toward preserving key physical and mental functions. That shift, he believes, is what keeps older people independent for longer.