This is a book about the importance of music in human evolution and its continued relevance to modern-day human society-how, from the very beginning of our species, musical communication has been a key component of prosocial, cooperative behaviors, acting as a counterweight to the other, newly evolved human communication system-language. It is about why music continues to be an essential part of human cognitive well-being in the twenty-first century. Early chapters review the amusia and neuroimaging literature to describe music processing in the brain, contrasting this with how the brain processes language. The time-course and possible drivers of human evolution, in particular the evolution of the human brain and its unique cognitive abilities, are discussed, with proposals as to why humans evolved two distinct communication systems from a presumed precursor, including hypotheses concerning the possible evolutionary benefits to the species of cooperative music-making (and dance). Two chapters then focus on a review of the neuroimaging literature and the links between music, altruism, and social cooperation. Areas of the brain that are active when performing mutually cooperative tasks are also active when listening to familiar and emotionally rewarding music, music that reinforces empathy and the sharing of affective states. Levels of the hormone oxytocin, known to enhance trust and prosociality, are also increased during group music-making. It is proposed that music played a key role in fostering trust and cultural cohesion in evolving modern humans. Finally, it is argued that music should form an essential part of education and should be more widely used as a therapeutic tool in clinical practice and rehabilitation.