The gifted musician Paul McCartney is also something of a founding father of mirror selfies, though he used an ex-girlfriend’s Pentax instead of a smart phone. This exhibition at Gagosian in London features 36 photographs that the 21-year-old McCartney took while on tour in 1963 and 1964. The subjects include his bandmates John Lennon, George Harrison, and Ringo Starr, foreign landscapes from Liverpool to Miami, and himself. “Most of them I don’t remember taking,” McCartney has said, “because it was a whirlwind.” —Carolina de Armas