Aging often looks very different on different people. There are some 70-year-olds that exercise regularly, have no trouble going for a walk around the block, and remain mentally sharp. Others really struggle at 70, and aren’t able to maintain a quality of life they’ve had in the past.There’s a growing field of medicine dedicated to better understanding how we age. And this field is looking less at the number on one’s birth certificate than you might expect. Dr. Aditi Gurkar, assistant professor of medicine at the University of Pittsburgh’s Aging Institute, is one of the researchers working to better understand why two different people may age very differently.Earlier this year, Dr. Gurkar and her team published a study that identified certain metabolites that seem to be reliable markers to index biological age. Dr. Gurkar joins Ira to talk about this study and the implications of better understanding a person’s biological age.Transcripts for each segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.