Some of my earliest memories are of summers with my grandparents, in New Delhi. I spent long, scorching months drinking lassi, playing cricket, and helping my grandparents find ripe mangoes at roadside markets. Then I’d return to the U.S., my English rusty from disuse, and go months or years without seeing them. At some point, my India trips started to feel like snapshots of loss. My grandfathers died suddenly, probably of heart attacks. My Biji, my father’s mother, fell and broke her hip in her seventies, and she spent her last years moving back and forth between her bed and her couch. My Nani, my mother’s mother, developed excruciating arthritis in both knees; in order for her to leave her fifth-floor walkup, my uncle practically had to carry her down the stairs. I have always wondered whether their fading vitality—the way their worlds contracted and their possibilities vanished—was an inevitability of aging or something that could have been averted.
Many of us have come to expect that our bodies and minds will deteriorate in our final years—that we may die feeble, either dependent or alone. Paradoxically, this outcome is a kind of success. For most of history, humans didn’t live long enough to confront the ailments of old age. In 1900, a baby born in the U.S. could expect to live just forty-seven years, and one in five died before the age of ten. But twentieth-century victories against infectious diseases—in the form of sanitation, antibiotics, and vaccines—dramatically extended life spans, and today the average newborn lives to around seventy-seven. Lately, though, progress has slowed. In the past six decades, medicine has added about seven years to the average life span—less by saving young lives than by extending old ones, and often in states of ill health. In many cases, we’re