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October 11, 2004

Stumbling backward, racing forward

David's post about the "Most Recent Common Ancestor" got me thinking about one group that I believe might have been isolated for the past 10,000 years, the indigenous peoples of Tasmania.1 Unfortunately, the living legacy of the Tasmanian people consist of individuals of mixed (predominantly white) heritage because of 19th century settler depredations.

I have been fascinated with Tasmanian aboriginals in the past because they were an example of a people who had "regressed" culturally over the past 10,000 years. After the rise of sea levels following the last Ice Age Tasmanians were cut off the Australian mainland. European observers noted that the Tasmanians looked somewhat different from conventional mainland aboriginals, for example, their hair was "wooly" rather than wavy. Some of the evidence that I have found suggests that even though the indigenous Tasmanian tribes never numbered more than several thousand they were divided into 6 groups, and there was intergroup phenotypic variation. This is a testament to the richness of the genetic background of any population, or the persistant power of selection in perpetuating group differences (likely sexual).

Additionally, I ended up stumbling upon this paper by Joseph Heinrich which posits a model for how the Tasmanians seem to have lost key elements of their material culture. Heinrich notes about the "Tasmanians had by the time of European discovery likely lost, or never developed, the capacity to manufacture bone tools of any kind, cold-weather clothing, fishooks, hafted tools, fishing spears, barbed spears, fish/eel traps, spear-throwers, bommerangs. To hunt and fight, Tasmanian men used only one-piece spears, rocks and throwing clubs. In all, the entire Tasmanian toolkit consisted of only about 24 items, which contrasts starkly with aboriginal Australians just across the Bass Strait who possessed almost the entire Tasmanian toolkit plus hundreds of additional specialized tools." This is the sort of tale that gets emphasized in Jared Diamond's Guns, Germs and Steel, though Heinrich posits an explicit model rather that offering a verbal description, placing a premium on the number of individuals in a network and the difficulty level of a skill in determining its evolutionary arc within a people (his model utilizes Price's Equation).

Obviously social networks and lines of communication are important (this can be prosaically illustrated in how different it is for two different individuals of similar academic accomplishments who have access to divergent social networks when they look for a job). The Tasmanians are an outlier, an extreme situation which is particularly illustrative of a principle, but if you read books like The Genius of China (Josehp Needham) you will note that even "advanced" societies tend to be susceptible to the same forces. But obviously large, complex societies with open lines of communication are more resilient. In The Human Web William H. McNeill emphasies that "the West Eurasian information network" (which has expanded to become coterminus with the world) became progressively tighter and more robust with each ascending cycle (additionally, its tendency toward polycentrism lent it some redundancy). Is it any wonder that civilization began in the Middle East? Or that New World civilization began in Meso-America?

I think this should emphasize to us the importance of open social networks, even within a culture. The profusion of connections made via the internet might not be relevant for our social life (our capacities to make friends have a limit, internet personals facilitate natural tendencies rather suggesting a multiplier effect), but it seems that it will aid in the progression of our material culture to ever ascending heights. The stumbling forward and back of diverse world cultures reiterates to us the interlocking nature of our cognitive capcities and the sociocultural matrix within which it manifests itself. Sounding a bit less pretentious, our cultural creativity is contingent upon our cognitive capacities, but does not flow inevitably.

Addendum: Steve Olson tells Carl Zimmer that he thinks at least a few individuals made the journey from Oz to Tasmania in 9,000 years. If I was a betting man, I would agree. But, this is the situation where I think that possibility, that is, lineal isolation, is the most likely.

1 - It seems plausible that Indonesian sailors washed up in Northern Australia, so their ancestry lines probably tie Australian aboriginals with the rest of the world.

Posted by razib at 12:35 PM