Finding an evolutionary explanation for the origins of music serves as a rich test of broader ideas on the emergence of mind and the evolution of mental processes. Charles Darwin and Herbert Spencer both offered evolutionary explanations for the origins of music, indicating the importance of the question for these two leading nineteenth-century students of “descent with modification.” Their discussion unfolded between the publication of Spencer’s “The origin and function of music” in 1857 and Darwin’s commentaries on music in The Descent of  Man in 1871 with an addendum Spencer offered to his original article in light of Darwin’s views. They had conflicting views on the lines of causation, asked differing questions, and had fundamentally different approaches. Their exchange laid the foundation for the discussion among contemporary adaptationists and nonadaptationists and contributed to the thinking of those who argue for Mixed Origins of Music or that it is a Transformative Technology of Mind.