Don't get me wrong. In itself, learning to cooperate certainly conferred enormous advantages on humans. Evidence of effective cooperation, in strictly practical terms, among virtually all human groups abounds. Nevertheless, despite evidence that human singing may have originated in the highly cooperative, interactive vocalizations of certain apes and gibbons, it remains difficult to understand what there was, or is, about vocal cooperation per se that could have provided either primates or humans with a competitive edge. The hallmark of cooperation may be interaction, but what was there, specifically, about vocal (or even instrumental) music that would have made this highly distinctive type of behavior effective enough to be selected for according to the classic Darwinian model? While it's certainly possible that musical cooperation might have been helpful in encouraging humans to cooperate, it's not difficult to think of other, much simpler, types of cooperation that could have had the same effect.
Merker has suggested that rhythmic entrainment may have been "selected for as a means for signal competition in the context of mate selection during rhythmic chorusing," (Op. Cit., p. 8) but there is no evidence for such a function among either humans or apes. In a fascinating, but also rather fanciful, recent paper by Ellen Dissanayake, entitled If music is the food of love, what about survival and reproductive success?, the author concentrates on certain musical features of mother-infant interactions. Significantly, she points to "interactive behaviors" between mother and child that
take place . . . sequentially, in bouts of 1.5 to 3 seconds, on a time base, so that each partner in the dyad reacts and responds contingently to the other’s signals within one-half second or less, anticipating and participating in an ongoing, changing, cocreated engagement. I propose that the dyadic coordination developed in mother infant interaction is likely a precursor of human music in which individuals mutually coordinate their voices and body movement in temporally and dynamically structured sequences (my emphasis, p. 177).
Since, as we have learned, a very similar type of interaction, also "paced at roughly 2 Hz" (Merker, Op. Cit., p. 7), i.e., two times a second, is characteristic of Bonobos, Dissanayake's observations seem remarkably consistent with the notion of a possible link between human and Bonobo vocalizations, reflected in the structure of the mother-infant bond.
Dissanayake moves on from there to consider "A HYPOTHETICAL PROGRESSION FROM PROTO-MUSIC TO MUSIC" based on the invention of "ceremonial ritual":
Like music and the other arts, ritual ceremonies occur universally in human societies. Indeed, the arts and ritual tend to occur together. Although human ceremonies are not instinctive — and indeed are culturally highly varied and complex — I propose that they build upon the proto-musical capacities and sensitivities that developed during human evolution to create and reinforce the mother-infant bond. . . . Emancipated from their maternal-infant origins, the elements of what eventually became music were probably first developed and elaborated by individual cultures, ancestrally, in religious practices (ritual ceremonies), which served to unite groups temporally and hence emotionally, as their proto-musical sources did for mother-infant pairs (p. 178).
As I see it, this sort of thinking, however interesting, and indeed suggestive, becomes far too vague far too quickly. We are still left wondering what it is about either mother-infant interactions or ceremonial rituals that caused something so distinctive and complex as musical behavior to emerge.
(to be continued . . . )