Genes and homogeneous trading groups: A comment on Janet Landa’s target paper

Abstract

In her target paper Janet Landa (2008) presents compelling evidence that cultural group strategies are a major factor underlying the development and continuity of ethnically homogeneous middleman trading groups (HMGs). HMG traders pass on the values and institutions underlying within-group trust and punishment of free-riders which in turn makes the group successful in risky markets. Landa finds that despite geographical separation the same HMG strategy has been adopted by different ethnic groups to guarantee contracts in societies with weak contract law. The finding of convergent cultural evolution is an important contribution to our knowledge of this subject. I appreciate Landa’s autobiographical approach. She recounts the development of her analysis beginning with her theory of ethnically homogeneous middleman groups as club-like trading institutions for contract enforcement in the early 1980s, followed by the incorporation of signaling theory, then HMGs as cultural transmission units in early 1990s, and finally her conceptualization of HMGs as adaptive units within the frame of multilevel-selection theory. I find it significant that althoughLanda’s analysis relies ongene-culture co-evolution theory it does not explore biological factors. Landa realizes that such factors must be included in a comprehensive theory (Footnote 5) but chooses to focus on cultural causes. In this comment I discuss some ways in which the analysis might be rounded out to include behavioral biological factors and suggest how these contribute to the success and continuity of HMGs. Landa’s analysis provides some of the evidence needed to make this case. Let us take a closer look at some key concepts, starting with ‘adaptation’. The definition Landa quotes from Ghiselin entails survival and reproduction, which could