Wednesday, July 15, 2009

168. The Pygmy/Bushmen Nexus -- Part 8

At the risk of beating a dead horse, I'd like to present some additional findings, to make my point as forcefully as I can. I must add, however, that the genetic evidence is not always completely consistent and not every result presents the same picture. I'll have more to say on the interpretation of such anomalies a bit later.

We haven't yet seen any results representing purely male lineages, so let's take a look at a phylogenetic tree based on a comprehensive re-evaluation of the Y chromosome, published (in 2002) as Figure 1 in A Nomenclature System for the Tree of Human Y-Chromosomal Binary Haplogroups, by the "Y Chromosome Consortium":

(Again I'll remind you to right-click and select "Open link in a new window" to see an enlarged image.) While references to specific populations aren't given in this figure, a key to all the groups represented in this survey is provided in Table 2, on p. 346 and 347. The table contains 11 individuals referred to as "San" (i.e., Bushmen) as well as two each representing the Pygmy groups Biaka and Mbuti. Of the San, three are classified under A2*, with the others as A2b, A3b1, B2b1, and B2b4a. The Biaka are both classified under B2b4b, and the Mbuti under B2b* and E2b. With the exception of one Zulu individual classified under B2a1, none of the other groups represented belongs to either of the two deepest clades (branches), A or B. From the perspective of this particular survey of male lineages, therefore, we find a picture remarkably similar to what we've already seen from the mtDNA (i.e., female) and autosomal trees, with the Bushmen represented at the root of the tree (A), and Pygmy groups occupying the next deepest clade (B).

Here is one more mitochondrial tree, from a recent (2008) paper, The Dawn of Human Matrilineal Diversity, by Doron Behar et al., a project sponsored by the Genographic Consortium of the National Geographic Society:
The most obvious aspect of this tree is the emphasis on the striking division between the two deepest clades, LO and L1, and the clear division between "Khoisan" and "Non-Khoisan" populations, with the Khoisan groups limited to the deepest branches of the tree, LOd and LOk (consistent with Tishkoff's mtDNA tree, as we've already seen). In this case, the term "Khoisan" can be regarded as equivalent to what we've been referring to as "Bushmen." (N.B.: LSA stands for "Late Stone Age".) From my perspective, the most interesting aspect of this report are their references to the deep antiquity of the Khoisan lineages and their divergence estimate, as summarized in the abstract:
We paid particular attention to the Khoi and San (Khoisan) people of South Africa because they are considered to be a unique relic of hunter-gatherer lifestyle and to carry paternal and maternal lineages belonging to the deepest clades known among modern humans. Both the tree phylogeny and coalescence calculations suggest that Khoisan matrilineal ancestry diverged from the rest of the human mtDNA pool 90,000–150,000 years before present . . . (p. 1).
I've seen different estimates for the earliest divergence of Bushmen and/or certain Pygmy groups from the ancestral population, ranging from 35,000 years ago (Tishkoff) to from 72,000 to over 100,000 years ago (Chen), but this is the oldest and thus, to my mind, the most appealing. :-) If correct, then it would be possible to claim that our musical time machine might possibly take us back as far as 150,000 years into the past!

Naturally, you may complain that, despite the striking similarities of musical style among the various Pygmy and Bushmen groups of today, a recording of a particular performance by any one of them won't necessarily sound the same as what their ancestors would have sung back in the "stone age." And it's true, we have no reason to believe that any given song or any given configuration of musical notes is going to be exactly the same, since as we can already tell, no two recordings of contemporary Pygmy or Bushmen music are going to be note-for-note the same. Nevertheless, there are so many striking stylistic and structural similarities among all the groups I've been focusing on that it would be very difficult to see how the music of the ancestral population from whom all these various groups diverged, literally tens of thousands of years ago, could have seriously differed, stylistically or structurally, from what can be heard today. As I've already written in one of the earlier posts on this blog,
So what could the ancestors of the Pygmies and Bushmen have been singing 76,000 to 102,000 years ago? Would it have been something roughly similar, but perhaps more "primitive," maybe less intricately contrapuntal or not contrapuntal at all -- or perhaps not as well organized, less precise rhythmically, more loosely structured? Astonishingly enough, if the Pygmies and Bushmen of today indeed sing in a manner that even the experts find it difficult to distinguish, then it's hard to imagine how their common ancestors of 76,000 years ago could have been vocalizing much differently -- in any respect. Why do I feel so sure of this? Well, let's assume that the ancestral population had a different, or at least somewhat different, musical tradition at the time when the first group of Biaka Pygmy ancestors broke away from the "founder population," 76,000 to 102,000 years ago. Once the two groups had separated, then, in order for them to be so musically similar today, their music would have had to evolve in more or less exactly the same way despite the fact that they were no longer in contact with one another. And for the life of me I can think of no "sufficient reason" (to quote Liebnitz, whose "principle of sufficient reason" is one of the backbones of science) to explain such parallel evolution, or what evolutionists call "convergence." The only explanation that makes sense to ME is that the ancestral group must have been making music in a manner that would also be indistinguishable from "modern" musical practice, among their descendents, to the same experts, if they had had an opportunity to hear it.

We can only conclude that this particular musical tradition must have been passed down from generation to generation over a period of at least 76,000 years (assuming the genetic estimates are correct) essentially unchanged -- a conclusion that, if corroborated, would totally transform our notion of cultural evolution and the role of tradition in its history.

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