Entrainment in the biomusicological sense refers to the synchronization of organisms to an external perceived rhythm such as humanmusic and dance. Humans are the only species for which all individuals experience entrainment, although there are documented examples of entrained nonhuman individuals.
Beat induction is the process in which a regularisochronous pulse is activated while one listens to music. It was thought that the cognitive mechanism that allows us to infer a beat from a sound pattern, and to synchronize or dance to it, was uniquely human. No primate tested so far—with exception of the human species—can dance or collaboratively clap to the beat of the music. Humans know when to start, when to stop, when to speed up or to slow down, in synchronizing with their fellow dancers or musicians. Although primates do not appear to display beat induction, some parrots do. The most famous example, Snowball was shown to display genuine dance, including changing his movements to a change in tempo Beat induction can be seen as a fundamental cognitive skill that allows for music. We can hear a pulse in a rhythmic pattern while it might not even be explicitly in there: The pulse is being induced while listening—like a perspective can be induced by looking at an arrangement of objects in a picture. Neuroscientist Ani Patel proposes beat induction—referring to it as "beat-based rhythm processing"—as a key area in music-language research, suggesting beat induction "a fundamental aspect of music cognition that is not a byproduct of cognitive mechanisms that also serve other, more clearly adaptive, domains ".
Evolutionary function
recently suggested that the human ability to be entrained was developed by the forces of natural selection as an important part of achieving the specific altered state of consciousness, battle trance. Achieving this state, in which humans lose their individuality, do not feel fear and pain, are united in a shared collective identity, and act in the bestinterests of the group, was crucial for the physical survival of our ancestors against the big African predators, after hominids descended from the safer trees to the dangerous ground and became terrestrial.
