Final answer:
The "New" Miles Davis Quintet's turn to original music in 1965, with significant contributions from Wayne Shorter and Herbie Hancock, marked an important evolutionary step in improvisational jazz that reflected the transformative cultural movements of the Harlem Renaissance.
Step-by-step explanation:
In 1965, the "New" Miles Davis Quintet began exploring more original music, with contributions from members Wayne Shorter and Herbie Hancock. This signified a pivotal shift towards a new direction in improvisational jazz sounds, integral to jazz history and the evolution of the genre. Their music reflected the broader cultural movement typified by the contributions of African American artists during the Harlem Renaissance period, who sought to express their unique experiences and cultural heritage.
The renaissance of jazz during the 1920s in places like Harlem was a rejection of European classical mimicry. Instead, it embraced new forms like the blues, changing the musical landscape in America, with figures like W. C. Handy playing a critical role in shaping the music known as the blues. This era saw a rise in African American jazz bands, such as King and Carter Jazzing Orchestra, enjoying immense popularity among diverse audiences and contributing significantly to the jazz culture.
The improvisation and innovative sounds that characterized the music of the Miles Davis Quintet bear the influence of the eras that preceded them, including the transformation in cultural expression sparked during the Harlem Renaissance and the energy of jazz musicians who infused their work with elements of life in black enclaves such as New Orleans. The Quintet's expansion into original compositions continued this tradition of innovation and cultural expression.