Reply to Skoyles: Natural selection does appear to explain some cultural rates of change

Abstract

With reference to the letter from Skoyles (1), our article (2) tested the hypothesis that those aspects of culture that may affect outcomes of survival and reproduction would evolve at a rate different from that of those that will not. We showed that, in the case of functional versus symbolic design traits for oceanic canoes, the former evolved more slowly. This is a commonly accepted signal of negative (purifying) selection for genetic evolution and when interpreting the fossil record. Although it does not prove that natural selection was at work, it certainly supports that inference. We do not attribute rates of symbolic trait evolution to positive natural selection; we explicitly rule out this possibility in the fourth paragraph of our article. We propose instead that symbolic traits may be subject to cultural selection—a different process.