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 . . . )
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5 comments:
Nice post. Interesting and good review of the L1c lineage.
Just thinking that the process of branching out of peoples may be less confrontational and more amiable. Even if a population practices some sort of growth control, it may be unavoidable that at some times, maybe after a specially bountiful period, the resources cannot support the population anymore. At such moments a split may be just normal. And if there are plenty of virgin lands around, as was surely the case in the early times of humankind (and also after the OOA in Eurasia), such divisions may be just common because they are easy.
Everywhere people have expanded when they saw the opportunity. And, because of geography, expansion means also division - but not necesarily in bad terms.
Maju, I agree that founder effects don't necessary have to be due to disasters or disputes. A group of people might just get adventurous and take off in a canoe, get lost and never return. Or some group might accidentally find itself lost or isolated from the rest. But I'm not sure that such effects can be understood as the result of simple expansion, because we can assume that any normal group that expands into a neighboring field or valley would still want to maintain connections with its family and friends in the original location.
What seems clear, however, is that disasters or other types of isolating events that produce founder effects can by the same token produce sudden and unpredictable cultural changes that have nothing to do with the sort of incremental change most anthropologists assume to be a necessary aspect of cultural evolution.
But I'm not sure that such effects can be understood as the result of simple expansion, because we can assume that any normal group that expands into a neighboring field or valley would still want to maintain connections with its family and friends in the original location.
Sure. But if the process is relatively fast, with people expanding in few generations through an immense landscape the size of the USA (or even larger), such connections will inevitably be broken. Just imagine what kind of relations would have Californians, Texans and New Yorkers not even in a Paleolithic reality but in a Neolithic (but pre-modern) one. Without mass media and without fast transport, the links would just vanish in no time, languages would diverge rapidly, etc.
In a Paleolithic reality with very low population densities, the effects of drift (and initially also founder effects) would be immense. And if this is true for genetics, I wonder if it would not be true also for cultural elements.
I think that we can safely say that in the "great Eurasian expansion" (maybe after the OOA or maybe after Toba) people migrated quite fast (within a few thousand years) through South and SE Asia and neighbouring regions (coastal East Asia, Australasia). And there are physical barriers like mountains and swamps and narrow seas that would make sure that people could not keep their ancestral connections in way too many cases.
It's difficult to visualize this process because it's not something that happened in a lifetime, nor in few generations, but probably hundreds of generations passed, more than in all written history. But such a huge span of time was just a "short episode" in the context of the Paleolithic, which is like 30-40 times as large as written history from the Sumerians on (which is almost as good as saying since proto-Indoeuropean began to diverge, just in case you want a linguistic reference).
What seems clear, however, is that disasters or other types of isolating events that produce founder effects can by the same token produce sudden and unpredictable cultural changes that have nothing to do with the sort of incremental change most anthropologists assume to be a necessary aspect of cultural evolution.
I very much agree with this, just that I'd emphasize the sentence "other types of isolating events", like long distance migrations, even if these happened through the course of many generations.
I don't discard catastrophes (you have made a very solid argumentation in favor of Toba in fact) but I'm still not convinced they are a necesary part of the explanation.
Maju, the problem for me is that founder effects due to normal expansion of a population of the type you describe are not likely, as I see it, to produce significant changes in cultural traits that are selection-neutral, such as musical style. While the challenge of a new environment might well result in adaptive changes with respect to language (increased vocabulary or encounter with another group that speaks a different language), tool making, hunting or farming or building techniques, etc., there is every reason to believe that things like religious beliefs, rituals, music and dance will remain essentially the same, due to the power of tradition, a power that is all too easy to underestimate.
Again, as I've argued before, this is a matter of paying attention to basic scientific principles, notably the principle of sufficient reason. If there is no sufficient reason to assume that something will change, we must conclude, all other things being equal, that it will not change. Because things do not usually change for no reason. A disaster or a sudden disagreement, leading to a pop. bottleneck and/or founder effect provides a reason for the (sudden) change of a religious belief or a musical style. But the gradual expansion of a population from one region to another does not. All you have as an explanation in such cases is a very vague idea called "drift." But whereas drift can easily be explained in genetic terms (due to naturally occuring mutations) I don't see an equivalent in the realm of culture.
This is where most anthropologists and archaeologists will disagree with me, of course, because for most people it's easy to just assume that traditions will change from one generation to the next, maybe a little at a time until a major new tradition has "evolved." But if that were the case, the music of the Pygmies and Bushmen would have "evolved" over their tens of thousands of years of separation to the point that their musical styles would now be totally different. And when I look at other musical traditions as they have become established in various parts of the world I see similar patterns that could only have resulted from thousands of years of cultural inertia.
Sure, there will always be memory lapses, innovations, outside influences, but what the musical evidence tells me is that the overall patterns of musical style tend to remain the same -- unless forced to change by some external event, such as a devastating drought, earthquake, eruption that produces a major population bottleneck -- or else when a weaker population is dominated by a much stronger one.
I realize that I can sound dogmatic when trying to explain things in this way, but I am trying to follow the evidence, rather than just think about what might seem "reasonable" or "logical."
But whereas drift can easily be explained in genetic terms (due to naturally occuring mutations) I don't see an equivalent in the realm of culture.
Cultural mutations do happen indeed and I'd say that, in principle, memes are more easily changeable than genes. The case of languages is very clear, as they evolve and spread a lot faster than any biological process could.
But when you put it together with founder effects (and in the case of culture with other random influences: like mystic visions, neighbours, etc.) I do get a plausible non-catastrophist model for cultural change. The very fact of migrating is in itself challenging and may require unusual changes in order to face a new environment, what may alter the culture more than among those who stayed behind.
Good modern examples may be found in European population colonies, specially in America. I was just the other day thinking in the musical differences between Argentina and Mexico both to a great extent Spanish population colonies. But while you find signs of collective performance (some minor hocketing, clapping, group dancing, relatively large performing bands) in Argentina instead is all unison or at most duet for couple dance. I would think these differences stem from a historical much higher population density and more closely knit communities in Mexico than in the Pampas (if anything). But you cannot pinpoint to a catastrophe to explain these differences: it's more of a founder effect (or series of them), along with local drift.
These differences may seem relatively unimportant but they have happened, along with a linguistic divergence, in a very short period of less than 500 years, period in which the two regions have kept active ties among them and with the European metropolis. In the Paleolithic isolation could be much more intense and last for much longer periods, even if the weight of tradition was heavier.
But if that were the case, the music of the Pygmies and Bushmen would have "evolved" over their tens of thousands of years of separation to the point that their musical styles would now be totally different.
Is it possible that they preserved them more easily because they remained in their ancestral environments keeping also a culture that was in general more in agreement with what we could call the "essential human nature"? While other more adventurous peoples also innovated more and more in a complex process as they got removed from their original lands? Maybe the memes for innovation were the same as the memes for exploration and expansiveness. If you are raised in a culture that is more open to innovation, more curious, you are more likely to be able to leave behind some traditions at whim. This will happen more easily in small bands, specially if they keep only remote contacts with their relatives.
Also I wonder about the weight of genetics and upbringing in musical abilities in general. It's well known for example that in many cultures kids are fed with their ethnic music since the womb. As soon as you have some change in behaviour in a group of mothers, their children will be fed that too. If the group is tiny, that will be easier to happen just "accidentally".
I suspect hence that smaller groups will change more easily (stronger drift, also culturally) than larger ones. In the Arctic for instance nomadic groups are typically a small nuclear family or two, not the ideal enviroment for cooperativist music. Instead Bushmen and Pygmies always live in larger communities.
Dunno. These are my doubts and concerns. Though certainly I am impressed by the lost of P/B in South Asia, where, barring Toba, we should find similar diversity and cultural preservation or even higher than in SE Asia. So you may well be right in this particular case. The main problem I see is that West Eurasians are genetically little more than a subset of South Asians and you say that they do keep in some cases some P/B remnants.
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