Review of Mixed Messages: Cultural and Genetic Inheritance in the Constitution of Human Society, by Robert A. Paul. University of Chicago Press 2015.Modern cultural evolutionary theory has been developed mostly by people with biological training, such as E.O. Wilson, Robert Boyd, and Peter Richerson. The theory portrays the human capacity for cultural change as both a product of genetic evolution and an evolutionary process in its own right. The parameters of the cultural evolutionary process have been tuned by genetic evolution to lead to outcomes that enhance genetic fitness on average. As E.O. Wilson famously said, genes hold culture on a leash.Maybe, but as Peter Richerson has often said in reply, it’s a pretty big dog on the other end. The term “dual inheritance theory” signifies a more symmetrical relationship between genetic and cultural evolution as two streams of information that replicate across generations and mutually influence each other. The fact that the cultural stream evolved by genetic evolution says little about their current relationship. Just as we might someday be controlled by the robots that we invented, the genetic stream of inheritance can come under the control of the cultural stream.Where have cultural anthropologists been during the development of dual inheritance theory? For the most part absent. This is not the place to recount the troubled history of cultural anthropology in relation to evolution in particular and scientific inquiry in general. Suffice it to say that in many (not all) respects, dual inheritance theory is like a party thrown by biologists in which the cultural anthropologists weren’t invited and didn’t want to come.Into the breach steps Robert A. Paul, a distinguished socio-cultural anthropologist at Emory University. Paul got to know Robert Boyd as a departmental colleague during 1984-6, before Boyd moved on to other institutions (first UCLA and now Arizona State University). Ever since, Paul has been formulating his own version of dual inheritance theory, which he presents in his book Mixed Messages: Cultural and Genetic Inheritance in the Constitution of Human Society.Paul’s contribution to dual inheritance theory needs to be understood in context. He is not mathematically trained and the entire field of socio-cultural anthropology consists mostly of ethnographies—detailed descriptive accounts of human cultures and their symbolic meaning systems. His book consists of a long series of anecdotes drawn from ethnographies to illustrate his various points, without any attempt at representative sampling or quantification.This might seem like a weakness, but its strength can be seen by drawing an analogy with natural history information in biology. In Darwin’s day, almost all information about plants and animals was descriptive, which did not prevent him from formulating his theory of natural selection. Even today, detailed descriptive knowledge of organisms in relation to their environments—a “thick description”, as a cultural anthropologist would say--is required to experimentally test hypotheses. Since evolution is highly contextual, the thicker the description of the natural history of an organism, the better for knowing which hypotheses to test, what to measure, and so on. In short, natural history information is a prerequisite for studies that have the trappings of science.I have been making this point for many years, including for the study of religion. My book Darwin’s Cathedral is in the same mold as Mixed Messages. My main thesis is that religious communities are primarily adaptive at the group level, as Durkheim posited long ago, and that their seemingly non-utilitarian aspects contribute to their secular utility. I support my argument primarily with descriptive examples, such as the impact of Calvinism on the social organization of the city of Geneva during the 16th century. I acknowledge that I am cherry picking my examples and that more systematic studies are needed, but that illustrative examples can suffice at the beginning of an inquiry. Later, I went beyond my own first effort by studying a random sample of religions1, although the information that I worked with was still descriptive. More generally, the burgeoning field of evolutionary religious studies is increasingly taking on the trappings of science, but it will always be built upon a foundation of “natural history” information provided by scholars of religion.Socio-cultural anthropology is one of the main repositories of natural history information for human cultures and Paul is the first socio-cultural anthropologist brave enough to apply it to dual inheritance theory without apology. I could quibble with some details, but for the most part he demonstrates a solid understanding of the theory and its biological underpinnings. His contribution is to make the cultural stream of inheritance come to life with the ethnographic examples that he has chosen from cultures around the world. If we invert E.O. Wilson’s leash metaphor by associating genetic evolution with “dog” and cultural evolution with “man”, then Paul provides many examples of “man bites dog”, or cultural evolution containing and circumscribing genetic evolution.For example, a surprising number of cultures in the past have perpetuated themselves by importing children rather than through biological reproduction. This is dumbfounding to anyone who thinks that genetic evolution holds cultural evolution on a tight leash, but it poses no problem for dual inheritance theory. The size of any population is based on two inputs, birth and immigration, and two outputs, death and emigration. A culture can perpetuate itself with little or even no births as long as the immigration rate is sufficiently high. The incoming children must adopt the customs of the culture, but this is accomplished successfully by the childrearing practices and especially the rituals that induct children into adult society.Paul rightly understands that the great challenge (and genetic payoff) of the cultural stream of inheritance is to suppress disruptive forms of competition within groups so that the group can function as a cooperative unit. This point is already emphasized by theorists such as Boyd, Richerson, and myself, but Paul’s contribution is once again to make the theoretical point come to life with examples drawn from ethnographies around the world, which I found brimming with insights. As an example, customs that superficially appear as the domination of women by men might be better explained in terms of the suppression of male-male competition for women within groups and the promotion of solidarity among men in between-group competition.Reading Paul’s book made me long for a peace treaty between evolutionists and socio-cultural anthropologists. If this is what one socio-cultural anthropologist can do to make dual inheritance theory come to life, how about the entire discipline? Paul provides his own assessment at the end of his book (p309-10):The implication for anthropology more generally, I submit, is that evolutionary and biological theorists should take into account more than they typically do the critical work the cultural symbol system does in human social life, while social and cultural anthropologists ought to consider the need facing any human socio-cultural system to sustain biological reproduction, and forge an effective compromise. The prospects of this happening are rather dim; but, ironically, only because the dynamics I have identified in this book are also operative in the society of anthropologists: for is it merely an accident that we have biological theorists who tend to dismiss the importance of the socio-cultural sphere competing with socio-cultural anthropologists who generally ignore the role of biology and genetics in human social life? Or is it rather the genetic program and the cultural program duking it out once again, in our own public arena, and preventing us from seeing that a complete account of human social life cannot be “either/or,” but must be “both/and” to be true to our subject matter—the human social animal?Let’s hope that Paul’s contribution to a “both/and” view becomes a new norm for the field of anthropology as a whole.

  1. Wilson, D. S. (2005). Testing major evolutionary hypotheses about religion with a random sample. Human Nature, 16, 382–409.