On a Baltimore stage in May, Ann Wilson welcomed her audience. “We are Heart,” she said, introducing the chart-topping band. “We are Heart,” her sister Nancy echoed, a little quieter, nodding into the microphone.

Each woman’s body language responded to the other. “Still Heart!” Ann said in response to the cheers. “Yup,” Nancy nodded.

“Still Heart.” The introduction mattered. For a while it seemed the sisters might not share the stage again.

A rift had opened between them in 2016, when Ann’s then-new husband physically assaulted Nancy’s son. Heart did not tour for years. This year they were finally back, and while a cancer scare for Ann paused the tour, the tour resumes next year .

Heart’s endurance means something different than that of other rock stars still claiming the spotlight in their 70s. Ann and Nancy Wilson exemplify the complex power of sisterhood. When sisters collaborate toward revolution or success, their joined force comes with mutual caregiving and gratitude — to each other, yes, but also circumstance.

Even sisters who share a close bond have usually passed through periods of attenuation. This focus on shared credit subverts the typical American lionization of individual success. At the Democratic National Convention in August, Maya Harris talked about her sister, Kamala.

Their mother, Maya said, “raised us to believe that we could be, and do, anything. And we believed her.” The sisters were close growing up, and Maya chaired h.