A self-taught musician, McCartney is proficient on bass, guitar, keyboards, and drums. He is known for his melodic approach to bass-playing (mainly playing with a plectrum), his versatile and wide tenor vocal range (spanning over four octaves), and his eclecticism (exploring styles ranging from pre-rock and roll pop to classical and electronica). McCartney began his career as a member of the Quarrymen in 1957, which evolved into the Beatles in 1960. Starting with the 1967 album Sgt. Pepper's Lonely Hearts Club Band, he gradually became the Beatles' de facto leader, providing the creative impetus for most of their music and film projects. Of his Beatles songs, more than 2,200 artists have covered "Yesterday" (1965), making it one of the most covered songs in popular music history.