Leonard Guarente was 38 and already a tenured professor at Massachusetts Institute of Engineering when he made a decision to devote himself to one of the most alluring problems in biology: the best way to slow down growing old. More than a few decades afterwards, the seventy two-year-old Guarente is https://www.wsj.com/health/wellness/longevity-antiaging-leonard-guarente-business-f55643f4?mod=health_lead_story