Two major topics for any subfield of evolutionary psychology are the adaptive function (if any) and phylogenetic history of the mechanism or behavior of interest including when music arose in human ancestry and from what ancestral traits it developed. Current debate addresses each of these.
One part of the adaptive function question is whether music constitutes an evolutionary adaptation or exaptation (i.e. by-product of evolution). Steven Pinker, in his book How the Mind Works, for example, argues that music is merely “auditory cheesecake”—it was evolutionarily adaptive to have a preference for fat and sugar but cheesecake did not play a role in that selection process. This view has been directly countered by numerous music researchers.
Adaptation, on the other hand, is highlighted in hypotheses such as the one by Edward Hagen and Gregory Bryant which posits that human music evolved from animal territorial signals, eventually becoming a method of signaling a group’s social cohesion to other groups for the purposes of making beneficial multi-group alliances.
The evolutionary switch to bipedalism may have influenced the origins of music. The background is that noise of locomotion and ventilation may mask critical auditory information. Human locomotion is likely to produce more predictable sounds than those of non-human primates. Predictable locomotion sounds may have improved our capacity of entrainment to external rhythms and to feel the beat in music. A sense of rhythm could aid the brain in distinguishing among sounds arising from discrete sources and also help individuals to synchronize their movements with one another. Synchronization of group movement may improve perception by providing periods of relative silence and by facilitating auditory processing. The adaptive value of such skills to early human ancestors may have been keener detection of prey or stalkers and enhanced communication. Thus, bipedal walking may have influenced the development of entrainment in humans and thereby the evolution of rhythmic abilities. Primitive hominids lived and moved around in small groups. The noise generated by the locomotion of two or more individuals can result in a complicated mix of footsteps, breathing, movements against vegetation, echoes, etc. The ability to perceive differences in pitch, rhythm, and harmonies, i.e. “musicality,” could help the brain to distinguish among sounds arising from discrete sources, and also help the individual to synchronize movements with the group. Endurance and an interest in listening might, for the same reasons, have been associated with survival advantages eventually resulting in adaptive selection for rhythmic and musical abilities and reinforcement of such abilities. Listening to music seems to stimulate release of dopamine. Rhythmic group locomotion combined with attentive listening in nature may have resulted in reinforcement through dopamine release. A primarily survival-based behavior may eventually have attained similarities to dance and music, due to such reinforcement mechanisms . Since music may facilitate social cohesion, improve group effort, reduce conflict, facilitate perceptual and motor skill development, and improve trans-generational communication, music-like behavior may at some stage have become incorporated into human culture.
Another proposed adaptive function is creating intra-group bonding. In this aspect it has been seen as complementary to language by creating strong positive emotions while not having a specific message people may disagree on. Music’s ability to cause entrainment (synchronization of behavior of different organisms by a regular beat) has also been pointed out. A different explanation is that signaling fitness and creativity by the producer or performer in order to attract mates. Still another is that music may have developed from human mother-infant auditory interactions (motherese) since humans have a very long period of infant and child development, infants can perceive musical features, and some infant-mother auditory interaction have resemblances to music.
Part of the problem in the debate is that music, like any complex cognitive function, is not a holistic entity but rather modular —perception and production of rhythm, melodies, harmony and other musical parameters may thus involve multiple cognitive functions with possibly quite distinct evolutionary histories.