Cultural macroevolution matters

Abstract

Evolutionary thinking can be applied to both cultural microevolution and macroevolution. However, much of the current literature focuses on cultural microevolution. In this article, we argue that the growing availability of large cross-cultural datasets facilitates the use of computational methods derived from evolutionary biology to answer broad-scale questions about the major transitions in human social organization. Biological methods can be extended to human cultural evolution. We illustrate this argument with examples drawn from our recent work on the roles of Big Gods and ritual human sacrifice in the evolution of large, stratified societies. These analyses show that, although the presence of Big Gods is correlated with the evolution of political complexity, in Austronesian cultures at least, they do not play a causal role in ratcheting up political complexity. In contrast, ritual human sacrifice does play a causal role in promoting and sustaining the evolution of stratified societies by maintaining and legitimizing the power of elites. We briefly discuss some common objections to the application of phylogenetic modeling to cultural evolution and argue that the use of these methods does not require a commitment to either gene-like cultural inheritance or to the view that cultures are like vertebrate species. We conclude that the careful application of these methods can substantially enhance the prospects of an evolutionary science of human history.

Keywords: Big Gods; cultural evolution; macroevolution; phylogenetics; religion.

Fig. 1.

Percentage of Google Scholar search results containing the term “cultural evolution” from 1950 to 2010.

Fig. 2.

An independent model (A) of evolution alongside the dependent model predicted by the Supernatural Punishment Hypothesis (B) and the dependent model resulting from analyses of traditional Austronesian cultures (C). The red figure represents the presence of a MHG, and the black figure represents the presence of political complexity (PC). Arrows indicate the rates of change between states, and the width of the arrows are proportional to the size of the transition rates. (A) In independent models of evolution, the rate at which each trait is gained or lost is independent of the state of the other trait. In this example, cultures are more likely to gain PC than to lose it (rate c is lower than rate d). (B) In dependent models of evolution, the rate at which each trait is gained and lost can be dependent on the state of the other. In the model predicted by the Supernatural Punishment Hypothesis, the rate at which PC is gained is higher when a MHG is present (rate d) than when it is absent (rate b), and the rate at which PC is lost is lower when an MHG is present (rate g) than when an MHG is absent (rate e). (C) The resulting models from our analyses suggested that MHGs had little effect on the gain and loss of PC, but that MHGs were rarely gained in cultures without PC (rate a is lower than rate f).

Fig. 3.

(A) Ancestral state reconstruction of human sacrifice and social stratification on a maximum clade credibility consensus tree of 93 Austronesian languages. The circles at the tips of the tree represent the known traditional states of cultures, and the circles found across the nodes of the tree represent the state of prehistoric cultures inferred by a Markov chain Monte Carlo analysis in BayesTraits. In the analysis, 4,200 of the most likely possible trees were used, and the consensus tree is a summary of these trees for illustrative purposes. The gray at each of the internal nodes represents the proportion of trees sampled without this node and provides an indication of phylogenetic uncertainty. (B) The resulting dependent model shows that cultures with ritualized human sacrifice were less likely to lose social stratification than those that lacked human sacrifice (rate g is lower than rate e). Adapted from ref. .