Tuesday, January 5, 2010

274. The Baseline Scenarios -- 50: The Event

On the basis of the argument presented in the previous post, reinforced by the considerable body of evidence already presented in a great many earlier posts, I propose the following sequence:

1. The development of HBC (the Hypothetical Baseline Culture of our most recent common ancestors) from traditions inherited from the oldest human ancestors, based in turn on the behavioral patterns and traditions of their pre-human primate ancestors.

2. The development of HMC (the Hypothetical Migrant Culture of the Out of Africa émigrés) from HBC, as modified by events subsequent to the divergence of the proto-pygmy and proto-bushmen populations from the ancestral group. HMC would have been characterized by, among other things: Pygmy/Bushmen style vocalizing, featuring hocket/interlock and yodel, though possibly in a simplified form; new types of instrumental music, including hocketing wind ensembles, slit drums, and stamping tubes, most of which would not have been present in HBC; elaborate and sophisticated carving and mask making traditions; distinctive cave and rock painting traditions; tone language.

3. The spread of HMC, with its musical and artistic traditions and tone language, in colonies scattered throughout the Indian Ocean coast, from the western border of what is now Pakistan, through southern India, and onward to Southeast Asia, Island Southeast Asia, and the Sahul (New Guinea and Australia, joined at the time by a land bridge).

4. The occurrence of some sort of major event, most likely a large-scale disaster of some sort, centered in South Asia, that would have precipitated major changes in the population patterns, genetic markers and culture of all colonies along the coast of South Asia, but for the most part spared those to the east of India. In the areas most affected, those colonies that survived would have been seriously decimated, producing what geneticists refer to as “population bottlenecks.” The event could have been: a major volcanic eruption, such as the explosion of Mt. Toba, ca 74,000 ya – the prevailing northwesterly winds would have carried vast amounts of Toba ash into the heart of the South Asian Peninsula while sparing most points due north, east and south of the eruption site (in northern Sumatra); a major Tsunami, centered somewhere southeast of India would have had much the same effect – the southern route implies a maritime culture, focused on sea-based resources, and thus especially vulnerable to an event of this sort; a major flood – weather patterns affecting the Indian Ocean area are dominated by the monsoon cycle, which can produce very heavy flooding during the summer months; a major drought – the same monsoon cycle can produce several successive months of little to no precipitation, and an anomalously weak monsoon season could leave the entire area seriously devoid of water.

5. A period of recovery, which would entail multiple founder effects in all groups that had experienced bottlenecks. Founder effects, resulting from severe depletion of population size, are known to produce changes in both the genetic and morphological makeup of a population, and could certainly produce many cultural changes as well. I’ll be discussing some specific consequences of such changes in future posts, but on the whole it’s not difficult to see how such an event and its aftermath could have produced the gap we now see in Southern Asia, where certain key features of African culture have vanished, only to “reappear” east of the Indian border.

6. What remains to be explained is the situation in what was once the Sahul, where we now see a very clear and also very mysterious difference between the peoples, cultures and languages of New Guinea and Australia. I’ll be dealing with this issue in future posts as well.

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