We investigated the origins of these two groups and the interactions between them, by analyzing mtDNA variation in 1,404 individuals from 20 farming populations and 9 Pygmy populations from Central Africa, with the aim of shedding light on one of the most fascinating cultural transitions in human evolution (the transition from hunting and gathering to agriculture).The paper relates the cultural divergence of the two groups to the spread of agriculture in Africa only about 3 to 5 thousand years ago, though the genetic divergences of their various lineages has to be much older. The picture is complicated by evidence of continual maternal gene flow from Pygmy to Bantu groups, due to occasional intermarriage between Pygmy women and Bantu men (p. 1600).
The paper is especially interesting for its "Phylogenetic tree of complete mtDNA sequences belonging to haplogroup L1c" (p. 1598):
(For a larger image, right click to "Open link in New Window".)
While the tree is complex and the relations between the Pygmy groups (highlighted in orange at the bottom) and the farmers (highlighted in blue) isn't obvious, note that all the rightmost groups but one are farmers and most of the leftmost groups are Pygmies. The capital letters encased in either yellow or blue at the bottom are abbreviations of tribal names, e.g., BAKO for Bakola Pygmies; BAK-CC for Baka Pygmies of Central Cameroon; TEK for Ateke; PUN for Punu; etc.
Note the deep genetic division at the top right, where L1c branches off into two subclades, L1c'1'2'4'6, to the left, and L1c3 (exclusively Bantu), to the right. Another important division can be seen just below, were L1c1 branches off into two subclades; the leftmost, L1c1a, representing mostly Pygmy groups, while the rightmost are mostly Bantu.
An important aspect of this tree is what it tells us about the difference between a lineage and a population. As you can see, some of the lineages are associated with more than one group, and a single group (such as, for example, BAK-CC) can be divided among two or more lineages. This situation represents a problem for population geneticists, who are continually being reminded that their trees represent relationships among lineages and not populations; and, consequently, that their attempts at reconstructing early migrations on the basis of genetic evidence alone will always be somewhat vague and indeterminate. This is where the musical evidence can be especially useful, since, like so many other cultural traditions, musical style can be much more easily associated with a given population and its history.
When we consider genetic divisions such as the branchings from L1c, and a bit later, L1c1, we must ask ourselves whether such divergences could have led to cultural, or, more specifically, musical divergences as well. As I see it, there is no law telling us that a genetic branching must also lead to a musical one, and there are no doubt many cases where a bottleneck and/or founder effect had no influence on any aspect of culture. However, it's not difficult to see how, under certain circumstances, the same forces that led to the creation of a new lineage could produce significant cultural changes -- or vice versa.
Since it developed in Africa many thousands of years after their genetic divergence, it seems unlikely that agriculture could have been directly produced by the same forces that divided Pygmies and proto-Bantu speakers tens of thousands of years ago. Yet it's very tempting to assume that two groups with such radically different "destinies" might well have gone their separate ways initially due to certain fundamental differences that might have led the one group down the path to radical change while the other remained, in so many ways, the same. Did the early ancestors of the Bantu farmers experience some sort of disaster, similar to what happened to the Ik, an experience that might have left them with more competitive, aggressive and individualistic tendencies? Did a drought or some other significant event deprive them of their normal sources of food, forcing them to invent alternative means of supporting themselves?
Or was there some sort of dispute, causing a family that might have been a bit more ambitious or naturally aggressive to question the egalitarian ideals of the group as a whole, to the point that it decided to take off on its own to begin a new lineage with a new set of socio-cultural standards more in line with its own. Such disputes might have been common among our earliest ancestors, why not? But in most cases the breakaway group, or its descendants, might not have survived, so we would lack any contemporary record, either genetic or musical, of its existence.
In any case, if a breakaway group (genetically, a founder group) were more individualistic and less egalitarian, it's not difficult to see how such a cultural ideal might be reflected in a vocal style more in line with what we now find so often among Bantu speakers, where a leader's part is distinguished from that of the supporting group. Individualism might easily lead, as well, to other forms of role playing and specialization, encouraging certain gifted individuals to develop their skills in the design and performance of certain instruments. Thus, single-pitched pipes, used previously as part of hocketing ensembles, might be turned into flutes with finger holes, and musical bows, with a single string, might be crafted into harps, lyres and zithers. The same sort of specialization, and related competition to excel in a particular craft or skill, might well have led to the development of metallurgy, independently invented among African Bantu speakers, and ultimately the array of technologies needed for the development of agriculture, also independently invented in Africa.
(to be continued . . . )