December 23, 2010

Modeling cultural diversity, local extinctions, etc.

Before I forget, just a quick mention of another potentially interesting paper published at PLoS ONE this week:


L.S. Premo and S.L. Kuhn, Modeling Effects of Local Extinctions on Culture Change and Diversity in the Paleolithic. PLoS ONE 2010. Open access.

Abstract

The persistence of early stone tool technologies has puzzled archaeologists for decades. Cognitively based explanations, which presume either lack of ability to innovate or extreme conformism, do not account for the totality of the empirical patterns. Following recent research, this study explores the effects of demographic factors on rates of culture change and diversification. We investigate whether the appearance of stability in early Paleolithic technologies could result from frequent extinctions of local subpopulations within a persistent metapopulation. A spatially explicit agent-based model was constructed to test the influence of local extinction rate on three general cultural patterns that archaeologists might observe in the material record: total diversity, differentiation among spatially defined groups, and the rate of cumulative change. The model shows that diversity, differentiation, and the rate of cumulative cultural change would be strongly affected by local extinction rates, in some cases mimicking the results of conformist cultural transmission. The results have implications for understanding spatial and temporal patterning in ancient material culture.

This mention is not adhesion. I find the modeling potentially interesting in its essentials but I surely have many discrepancies on issues such as assuming tiny "populations" of some 25 individuals in black and white (life or death) states. Such size is ok with operative hunter-gatherer bands but these are not "sovereign" units but just dynamic and fluctuating economic ones, integrated in larger groups. Probably a better size would be something like 100 or 200 people but again integrated into larger units of several hundreds to several thousands (tribes or nations).

Also we have to consider that people change "clans", for example when marrying. So cultural, as well genetic flow is persistent at least within the borders of the ethnicity, which are anyhow generally open. So I guess that the modeling needs a lot of refinement but still it is a curious speculation - or exploration if you wish.

Something I do agree is in the authors founding their research on previous works that strongly suggest that population size and specially connectivity is critical in driving and maintaining the rhythm of innovation.

1 comment:

  1. First hand accounts from the colonial era in North America document frequent demises of entire small tribes, sometimes due to the death of all members due to poor hunting results or warfare, and sometimes due to the reduction of the tribe below viable numbers forcing those remaining to attempt to adhere to one or more other tribes.

    Some of that was due to a heightened death rate due to exposure to European diseases and dramatic changes in the ecology as a result of colonization, introduction of non-native species, and mass indigeneous population death. But, the notion that local extinction of subgroups of hunter-gatherer populations in the Paleolithic was common enough to make a major long term dent in the persistance of culture does seem plausible.

    Also, one suspects that there would have been some specialization, with designated tribal story tellers or master tool makers who preserved the tradition, and that the loss of one or two individuals who held these roles before successors could be trained could significantly impair cultural continuity.

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