They thought it might explain why their health had diverged. Instead, it stirred up feelings that weren’t so easily quantified.

© Vivian Dehning; photographs by Annie Flanagan for The New York Times

Scientists have sequenced his genome for the first time, hoping the world’s oldest land animal can offer clues into the genetics of longevity.

© Gianluigi Guerica/Agence France-Presse — Getty Images

Artificial intelligence was used to help develop a drug candidate, rentosertib, for a rare lung condition. Its maker says the drug also seems to reduce the biological hallmarks of age.

© Laurie Chen/Reuters