Free The World in Six Songs: How the Musical Brain Created Human Nature by Daniel J. Levitin Page A

crucial use of music was for easing tensions within the larger social groups that were forming—group cohesion. Here, music can be traced back even before the emergence of our own species, Homo sapiens sapiens, to tens of thousands of years before with a common ancestor, Homo erectus . Around the time that Homo became bipedal and erect, they left the relatively safe cover of tree living to live on the savannah; the principal advantage was a greatly increased supply of food as Homo became hunters, but there were disadvantages as well to be weighed. As Mithen notes:
    Away from the cover of trees, safety can only be found in numbers. . . . There is, however, a cost: social tensions leading to conflicts can arise when large numbers have to live continuously in close proximity to one another.
     
    Easing these social tensions was not trivial. Among nonhuman primates, this is generally accomplished by grooming one another (picking nits and cleaning the hair of a friend); in fact, the closeness of a relationship between two primates can often be determined simply by the amount of time one spends grooming the other. But with the increased size of living groups—which was necessary for mutual protection—physical grooming of all one’s friends and allies becomes impossible. The Oxford anthropologist Robin Dunbar proposed the vocal grooming hypothesis as the origin of vocal communication—the idea that hominids developed vocal communication (music or language) in order to indicate their cooperation and alliance with larger numbers of group members at once.
    All over the world and in disparate cultures, human singing is present in two broad styles or forms: strict synchrony and alternation. In strict synchrony, the singers lock their vocalizations in with one another, such as we do in songs like “Happy Birthday” or most national anthems. This requires the ability to anticipate what is coming next in the song (combining cognitive operations of memory in the hippocampus and prediction in the frontal lobes), and then to create what neuroscientists call a motor action plan —a specific set of instructions sent to the motor cortex to enable one to sing, drum, or otherwise move the body in time with what others are doing. Part of the evidence that prediction processes are involved when we synchronize our singing, hand clapping, or other musical gestures to those of a group is in the small, microtiming errors people make in trying to synchronize: Far more often than not, they are early in matching others’ musical behavior. This tells us that they’re not waiting to hear the next beat before they try to play it; rather, they’re anticipating when it will come and preparing a response before it happens. The coordination of activity in these three brain regions (hippocampus, motor cortex, and predictive centers in frontal lobes) would be dependent on the larger prefrontal cortex (than other hominids) that humans evolved.
    Alternation occurs when some members of the group deliberately don’t synchronize with others, singing either in a round (as when children sing “Row Row Row Your Boat” and some start at a different time than others) or when singing a “call and response” pattern such as in the children’s campfire song “Sippin’ Cider Through a Straw.” Call and response is often found in American gospel music, and is based on an ancient African tradition. Indeed, in sub-Saharan African cultures in particular, this style is considered emblematic of a democratic participation in the music. Call and response is also found in traditional Indian classical music (where it is called jugalbandi or sawaal-javaab in North Indian classical music), in Latin American music (where it is called coropregon) , and in European classical music ( antiphony). Alternation in particular requires perspective taking (the first of the three components of the musical brain), and can be seen as an exercise for or predecessor to other more