Percussionist/ethnomusicologist Bill Summers played a key role in shaping Herbie Hancock’s 1973 groundbreaking and platinum-selling Head Hunters record. Here, he reveals how “Watermelon Man” came about.

“I found a job in 1968 at a race track so I could still play music at night. There was a guy who worked shining shoes. Employees could not bet on races, so this guy was like a bookie. One day I bet a daily double. Both horses won, I ...