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The defining moment of James Jamerson's career was his collaboration on Marvin Gaye's iconic track, "What's Going On." His groundbreaking bassline, characterized by its smooth, melodic flow, intricate syncopations, and subtle fills, earned critical acclaim and set a new standard for bass playing in soul music. Jamerson's masterful performance not only elevated the song but also solidified his reputation as one of the most influential bassists in music history.