Nitzsche, Jones deserved a co-writing credit for "Under My Thumb", which Nitzsche recalled as being an unoriginal-sounding three-chord sequence until Jones discovered a Mexican marimba left behind from a previous session, and transformed the piece by providing its central riff. Wyman agreed, saying, "Well, without the marimba part, it's not really a song, is it?" During the recording sessions, Richards and Oldham dismissed Jones' interest in exotic instrumentation as an affectation. According to the music journalist Barbara Charone, writing in 1979, everyone connected with the Stones credited Jones for "literally transforming certain records with some odd magical instrument". While Nitzsche was shocked at how cruelly they treated Jones, he later said that Jones was sometimes absent or incapacitated by drugs. Hassinger recalled seeing Jones often "laying on the floor, stoned or on some trip" and unable to play, but that his bandmates would wait for him to leave rather than entering into an argument as other bands would. Because of Jones' distractions, Richards ended up playing most of the guitar parts for Aftermath, making it one of the first albums to have him do so. Richards later said he found the challenge musically rewarding but resented Jones for his unprofessional attitude when the band were under extreme pressure to record and maintain a hectic touring schedule. On some songs, Richards supported Wyman's bass lines with a fuzz bass part, which the music historians Philippe Margotin and Jean-Michel Guesdon suggest was influenced by Paul McCartney's use on the track "Think for Yourself" (from Rubber Soul). Aftermath was also the first Stones LP to be released with the majority of its tracks in true stereo, as opposed to electronically recreated stereo. Musical style According to the musicologist David Malvinni, Aftermath is the culmination of the Rolling Stones' stylistic development dating back to 1964, a synthesis of previously explored sounds from the blues, rock and roll, rhythm and blues, soul, folk rock and pop ballads. Margotin and Guesdon go further in saying the album shows the Stones to be free from influences that had overwhelmed their earlier music, specifically the band's Chicago blues roots. Instead, they say, the record features an original style of art rock that resulted from Jones' musical experimentation and draws not only on the blues and rock but also pop, R&B, country, Baroque, classical and world music. Musical tones and scales from English lute song and Middle Eastern music