Wednesday, May 30, 2007

18. The Bottleneck Continued

To better understand the bottleneck theory, let’s take a closer look at the set of evolutionary maps first presented in section 12. The map at the upper left, labeled “Out of Africa,” represents the earliest stages of the “Out of Africa” migration, which, according to most proponents of this model, proceeded eastward along the south Asiatic coast, all the way from Yemen, along the coasts of India, Southeast Asia and Indonesia (all one landmass at that time) to the Sahul (New Guinea and Australia, then one single landmass) and northward along the East Asiatic coast.

Musically, we see style families A1 through A5 represented in Africa. All appear to have been present among the original “Out of Africa” band, so the red arrows we see progressing along the Asiatic coast are intended to represent all five versions of P/B style. (Note the offshoot in northern India, labeled A3 & 4 – we’ll deal with that presently.) This map represents the situation after our migration “wave” reached the southeast coast of Asia, prior to the bottleneck event. Various colonies would presumably have been left all along the Asiatic coast.

Proceeding to the next map, labeled “Bottleneck Event,” we see a hypothetical “Tsunami” represented, which could have had a devastating effect on all the colonies along the coast of the Indian Ocean. Since the migrants may well have had a coastal culture, “beachcombing” for shellfish and other ocean-based food sources, a tsunami might well have destroyed entire populations. It’s also possible that the eruption of Mt. Toba was the cause of the bottleneck. In any case, a great deal of evidence, both genetic and musical, points to a major bottleneck of some sort, caused, in all likelihood, by some enormous natural disaster.

It’s important to note that any human colonies located beyond the Indian Ocean, on the east coast of Indonesia, the Sahul or the Asiatic mainland would not have been affected by either an Indian Ocean tsunami or the Toba explosion. (Since the prevailing winds would have been westerly, the ash from Toba would not have affected most areas to its east.) And it is indeed in these areas that we find, even today, most of the remnants of P/B styles A1 through A5, as indicated on the phylogenetic tree.

As for the rest, the people who’d been living along the Indian Ocean coast? Could they have survived? And if so, what would their lives have been like? We have no way of knowing, of course, but from the evidence we now have, both genetic and musical, the ensuing population bottleneck might well have been responsible for most of the diversity, genetic, phenotypic, cultural, and musical, that we see today.

Moving to the next map, “Postbottleneck Founder Effects,” we see the distribution of style families B1, B2 and B3, in their early stages, all presumably rooted in major changes, biological, environmental, social and cultural, that could have left their mark on whatever individuals would have survived. The discontinuities we have been discussing in the musical styles of so many indigenous peoples today could thus be explained by the cultural discontinuities produced by this one single major disaster.

B1 is represented in red, like the A superfamily, because, of all the post-bottleneck styles, it is still identifiable as African. This is what I have called “canonic-echoic” style, a form of canonically overlapping imitation very possibly derived from A4, “Canonic Interlock,” as indicated by the scored line linking A4 to B1. The styles can be quite similar, as is evident when we examine the list of individual traits (haplotypes) in each. The major difference is the presence of LC, for “loosely coordinated,” in B1. We find LC only very rarely in subsaharan Africa, where almost all forms of music are very tightly coordinated indeed. There are in fact no real traces of B1 anywhere in Africa, strongly suggesting that it must be a post-bottleneck derivative.

We have already discussed B2, “Breathless Solo,” at some length. What the map implies is that this style could have had its origin on the Indian subcontinent, rather than its current home, northern Eurasia, as a result of the same bottleneck event we’ve been discussing. Could it be the result of some later event, possibly some other disaster, or the effects of the ice age? Possibly, but it would have had to be rooted very early on in human history to have made its way into the many different, remote, places where it’s found today. And we must remember that Paleolithic Europe was dominated by a very similar, reindeer oriented culture, as far south as Spain, so groups such as the Saami, of northern Scandinavia, could be marginalized descendents of originally mainstream Paleolithic Europeans, the westernmost wing of bottleneck survivors who moved off in all directions from an Indian homeland. If their “breathless” singing style originated after one such wave had headed north to Siberia, then it would be difficult to explain how the same style could have made its way to Spain prior to moving north to Scandinavia, where the reindeer people would have been forced north during the Neolithic. Sorry about that long and confusing and admittedly speculative sentence, but it does tell you something about the scale of my thinking on this topic, which is wide ranging indeed.

While B2 seems in many ways almost the opposite of any of the African A styles, there are some very interesting points in common, as indicated by the scored line linking B2 with A2. The two styles are both characterized by yodel (especially in the well known Saami “joik” songs, but also reflected in the heavy glottalization found throughout this style area), continuous vocalizing (albeit interrupted by gasps for breath in B2), wide intervals, and an emphasis on “nonsense” vocables. It is thus possible to see how B2 might have emerged directly from P/B, but in a post-disaster setting where communal life might have broken down and individuals could have been forced into isolation for long periods.

I tend to see B2 as the root of other important styles that may have come later, through a gradual process that better fits our usual notion of “evolution.” The tree diagram shows a derivative of B2 branching off to a substyle called “Phrased Solo,” i.e., a development from the “breathless,” apparently unphrased singsong of Paleosiberian singing, to a type of melody organized according to what we can now call “phrases,” i.e., syntactic elements delineated by breaths. At least two branches survive today, one being B2A1, “Elaborate Solo,” a type of highly embellished solo vocalizing characteristic of many Asiatic groups. The Eastern branch of this style, especially in China, Korea and Japan is characterized by considerable glottal activity, possibly a clue to its origins in B2. The other branch, B2A2, is characterized by much less embellishment, lack of glottal emphasis, and strophic (or verse) form of the type most closely associated with the European lyric song and ballad. This is a style that appears to have its origin in Central Asia, where strophic songs are still an important part of the bardic repertoire.

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