Sunday, 2 March 2008

Cultural Natural Selection

An interesting paper by Rogers and Ehrlich, titled Natural selection and cultural rates of change, published in a recent edition of PNAS, has brought my attention to the issue if some principles of the Darwinian evolutionary theory might be applicable to cultural transmission. The findings document the intuitive reasoning that it should be so.

It has been claimed that a meaningful theory of cultural evolution
is not possible because human beliefs and behaviors do not follow
predictable patterns. However, theoretical models of cultural
transmission and observations of the development of societies
suggest that patterns in cultural evolution do occur. Here, we
analyze whether two sets of related cultural traits, one tested
against the environment and the other not, evolve at different
rates in the same populations. Using functional and symbolic
design features for Polynesian canoes, we show that natural
selection apparently slows the evolution of functional structures,
whereas symbolic designs differentiate more rapidly. This finding
indicates that cultural change, like genetic evolution, can follow
theoretically derived patterns.

Of course the mechanisms of change are different: in place of biological mutations we have innovation and cultural drift. But the stabilizing (or destabilizing) effects of selection on those traits that have strong link with reality which may influence the survivability of individuals and societies (canoe design, but also obviously, building design, food preparation etc.) are the same in mechanisms in biology and cultural change. The difference between the observed rates of change in functional and decorative design elements of canoes provide not only beautiful observational example of such differentiating process in action, but also are reminiscent of the `Spandrels of San Marco' discussion. Is it possible that a functional (i.e. selective) element in canoe design could come from a decorative change?
What was the origin of the high bows of the Viking boats? Was it technical/functional when conceived? I guess that yes, but perhaps there is more to the story?

In any case, this is a short but quite interesting paper.

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