The Role of Variation in Cultural Change -Abstracts

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F. John Odling-Smee

Where does human cultural niche construction fit in?

Evolutionary theory traditionally models a single inheritance system in evolution, genetic inheritance. Attempts to model human evolution exclusively in terms of genetic inheritance foundered when it was realized that human cultural activities, based primarily on human cultural inheritance can sometimes modify natural selection in human environments in ways that change human genetics. That led to dual inheritance models of human evolution, developed by gene-culture coevolutionary theorists, based on genetic and cultural inheritance. Independently, Odling-Smee, et al (2003) developed niche construction theory, based on genetic inheritance and ecological inheritance in all organisms. Combining niche construction theory and gene-culture coevolutionary theory subsequently promoted a triple inheritance model of human evolution incorporating genetic, ecological and cultural inheritance. It now appears possible to reduce human cultural inheritance, inclusive of material culture and cultural knowledge, to potent components of a general human ecological inheritance. This paper argues the case for doing that.

Odling-Smee, F.J., K.N. Laland & M.W. Feldman. 2003. Niche construction. The neglected process in evolution. P.U. P.

Steve Lansing

The Domain of the Replicators: cultural evolution and the neutral theory

Darwinian models of cultural evolution consist of three types. If culture affects biological evolution, then cultural evolution is the heritable non-genetic transmission of anything that affects the reproductive success of individuals. Alternatively, culture may be viewed as a domain apart from biology, which evolves by Darwinian selection. Finally, in models of gene-culture co-evolution, selection occurs in both culture and biology. Evolutionary game theory offers a mathematical foundation for understanding evolution in all three cases, and interest in this approach is growing. Proponents argue that game theory is the appropriate tool whenever the success of an individual depends upon others. An evolutionary dynamic is added by modeling selection with the replicator equation, which instantiates Fisher’s Fundamental Theorem of Natural Selection (1930). But Fisher’s Theorem became obsolete in genetics after the discovery of DNA and has been forgotten by most geneticists. Geneticists and ecologists now infer selection by showing departure from Kimura’s null model of neutrality. Kimura’s approach shifts the level of analysis from the fitness of individuals to the effects of selection at the population level.

A central tenet of human behavioral ecology holds that facultative behaviors, such as dominance, produce fitness effects that are subject to cultural selection. But evidence for such selection is indirect, based on short-term statistical associations between behavior and fertility. Kimura’s neutral theory can be adapted to test for cultural selection in non-coding regions of DNA. Analyses of haplotype distributions defined by neutral microsatellites on the non-recombining Y-chromosome from 43 Indonesian communities show that differential selection among men is uncommon. Male dominance seldom translates into increased fertility over deep timescales, and short-term reproductive skew rarely produces long-term evolutionary benefits. The discovery that neutral processes explain most haplotype distributions in these communities parallels earlier results from the development of neutral theory in genetics and ecology.

James Truncer

Why Cultural Elaboration? An Evolutionary Perspective.

Cultural elaboration – the investment of time and energy into activities that do not have a clear role in enhancing survival or reproduction – is a common feature among complex societies and often highly visible archaeologically (e.g., mounds, grave goods of exotic materials, etc.). Such costly activities need to be explained at a theoretical level, and evolutionary models offer such a theoretical framework, but further refinement is needed. While many forms of cultural elaboration appear not to be adaptively neutral because they divert time and energy away from subsistence pursuits, we need to develop the analytic tools to show that they are not. There are many different forms of cultural elaboration and we need to ensure that the variability we are interested in explaining is accommodated by models we use. Evolutionary models need to include considerations of age structure and fertility in human populations, and we need better analytical tools to assess whether the economic costs of cultural elaboration have demographic and selective consequences in specific empirical cases. Many expressions of cultural elaboration clearly involve group-level activities, so evolutionary models that only consider benefits to individuals need to be extended to consider potential benefits to groups of individuals and the integrative mechanisms that facilitate large-scale cooperation. These refinements will require that archaeologists shift from describing modal tendencies to documenting variation in terms of frequency across time and space.

Melissa J. Brown

Structural Dynamics of Cultural Variation

Ethnographers have long known about the existence of cultural variation within a society, but have rarely documented the frequency of different variants. Evolutionary modelers are also well aware of population structure, but have rarely incorporated social structure into models of cultural change. Moreover, both ethnographers of recent years and evolutionary modelers have rarely distinguished between social and cultural inheritance tracks, yet the transmission of cultural information has a different dynamic than the construction or transformation of the social order, which is more akin to a niche. Examination of all these factors has proven useful in understanding marriage change in Taiwan, where the dynamic between political structure and ethnic identity affected the frequency of marriage forms and even religious practices.