By David Sloan Wilson and Joseph Henrich

Paleontologists tell us that numerous Homo species once roamed the earth, although only Homo sapiens remains. Several Homo species still inhabit economic world, however — the world as described by traditional economics. The most common is Homo economicus, whose preferences and abilities were described by neoclassical economists a long time ago. More recently, behavioral economists described a new species called Homo anomalous, because it departs from H. economicus in so many ways. Now a brand new species has been discovered by a multi-disciplinary team of scientists. I’ll call it Homo bioculturus and it might well become the one that inherits the world of economics.

Joseph Henrich is one member of the team that discovered H. bioculturus and his new book, The Secret of Success: How Culture is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter, is arguably the best way for the economic profession to learn about it. Henrich is an intellectual Indiana Jones, equally at home slashing through the Jungle or conducting lab experiments. He spearheaded the famous “15 Societies Study” that played experimental economics games in traditional societies around the world. He recently moved from the University of British Columbia, where he was jointly appointed in the Departments of Psychology and the Vancouver School of Economics, to Harvard University’s Department of Human Evolutionary Biology.

DSW: Greetings, Joe, and welcome to Evonomics.com.

JH: Hello David! It’s great to be with you.

DSW: First, let me congratulate you on writing such a terrific book. Without attempting to flatter you, it is a tour de force—great fun to read in addition to brimming with ideas—my current favorite book for recommending to others. Second, let me ask you to provide a synopsis for an economically oriented audience.

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JH: Thanks very much, David. That means a lot coming from you.

The central idea that the book follows is that human cultural learning gives rise to a system of cumulative cultural evolution that, over generations, gradually produces increasingly complex tools, technologies, bodies of know-how, communication systems and institutions. This is effectively a second system of inheritance that has been interacting with our genetic inheritance for more than a million years. Consequently, understanding humans from an evolutionary perspective requires considering the interaction between these two inheritance systems. The book is built around a series of examples. I use examples of how our anatomy, physiology, and psychology have evolved genetically in response to culturally constructed practices, like fire and cooking, and institutions such as those related to marriage and kinship.

One central idea that might be of interest to economists is the notion of the collective brain. The process of cumulative cultural evolution that arises from the specifics of how individuals adaptively learn from other members of their social groups means that our ability to produce increasingly complex tools technologies and know-how depend on the size and interconnectedness of a population, over time. This means that innovation, in part, depends on the flow of information among a large population of minds.

I also make the point that many of our cognitive abilities that we may think of as innate are actually bootstrapped up via cultural evolution from much simpler and less impressive cognitive abilities. Cumulative cultural evolution produces things like numerical systems, spatial reference systems, pulleys, levers, elastically stored energy and complex languages Without these, we’re much less impressive.

DSW: Many readers will be familiar with the school of thought known as evolutionary psychology and associated with names such as Leda Cosmides and John Tooby, which could be called Homo modularus. Your portrayal of the human mind as a product of evolution is very different. Could you please expound on the difference?

JH: Let me start by saying that I see myself as engaged in an enterprise that is largely convergent with that of the Santa Barbara crowd. I haven’t spent a lot of time thinking about the similarities or differences in our particular approach. Clearly, however, others think our approaches are very different since I’ve recently debated both Leda and one of her students, Max Krasnow. These events were driven by other peoples’ curiosity about the two approaches.

Nevertheless, when I look at the work of Cosmides, Tooby and their students here’s what I don’t see:

Consideration of evolutionary hypotheses in which culture or cultural evolution created the selection pressures that resulted in some particular aspect of human psychology. An explicit effort to model cultural evolution and consider how a variety of genetically evolved adaptive biases or mechanisms can generate cultural adaptations related to things like tool-making, food choice, institutions, social norms, religions, and marriage systems. A methodological approach that exploits the immense phenotypic and psychological diversity found across the human species. Instead they mostly run experiments on undergraduates. I think there’s good reason to believe that undergraduates are possibly the worst population from which to make inferences about human nature. I think it’s pretty hard to tell when you’re tapping human nature and when you’re tapping, for example social norms, by studying undergraduates only. A theory of human evolution: how and why did our particular brand of primate branch off and evolve along such a unique evolutionary trajectory. They often point me to a paper called “The Cognitive Niche“. When I read the paper I don’t see a theory. I see a list of capacities, not a generative selection pressure that say how and why they emerged. Having a high level theory of what drove human evolution has a lot of advantages over the lower level theorizing that we’ve seen emphasized at Santa Barbara.

These are all things I develop or discuss my book.

Interestingly, in my debates with both Max and Leda, they made it clear that they have no problem with culture-driven genetic evolution in general. From my perspective, Max went so far as to argue that this idea flows directly out of Tooby and Cosmides 1992 chapter in The Adapted Mind. I don’t see it there so I’ve been meaning to ask Max for a page number.

My book comes at the modularity debate from a totally different angle. It’s focused on using an understanding of natural selection and evolution to think about the emergence of our capacities for learning. From a domain specific view, the “domain” is the domain of acquiring information, ideas, beliefs, values, preferences and motivations from other people via cultural learning. I make a case for what I’ve called, “model-based biases” and “content-based biases”. The model-based biases focus learners’ attention and memory on those individuals most likely to possess adaptive information like individuals who are particular skilled, successful or prestigious. Crosscutting these biases, are a set of intention memory and inferential biases that facilitate the learning of certain kinds of information, information about food, fire, social norms and projectiles.

Are these domain-specific? I thought they were but I really don’t care. It doesn’t help me to do better science if we call these domain specific or not. Max Krasnow tells me they’re not domain specific because they are not about “mating”, “foraging”, “parenting” and “cooperation”. Interestingly, Clark Barrett who is also from the Santa Barbara school of evolutionary psychology gives a view much closer to mine in his latest book, which is excellent by the way.

DSW: That’s very instructive! I think it would be equally instructive to relate your paradigm to various schools of thought in economics, such as orthodox economics, behavioral economics, the brand of evolutionary economics associated with Richard R. Nelson and Sidney G. Winter, and the brand of evolutionary economics associated with Friedrich Hayek. Let’s begin with the fabled Homo economicus.

JH: well, in our work we’ve tried to test some of the basic predictions made by the Homo economics model using some simple tools from behavioral economics applied across a diverse swath of human societies. Not only do we find that the Homo economicus predictions fail in every society (24 societies, multiple communities per society), but instructively, we find that it fails in different ways in different societies. Nevertheless, after our paper “In search of Homo economicus” in 2001 in the American Economic Review, we continued to search for him. Eventually, we did find him. He turned out to be a chimpanzee. The canonical predictions of the Homo economicus model have proved remarkably successful in predicting chimpanzee behavior in simple experiments. So, all theoretical work was not wasted, it was just applied to the wrong species.

I think the major problem with moving away from the Homo economicus model lay in what to add to the model. The economists I know are nervous about moving away from this canonical model because they worry that it opens the door to the willy-nilly adding of different preferences to fit the data. What the field needs is a disciplined way of theorizing and testing preferences (or irrational beliefs) that can then be added to the model.

This is what I think a fully-fledged evolutionary approach can add to economics — theory that endogenizes beliefs and preferences within a cultural and genetic evolutionary dynamic. Economists can keep all that powerful utility maximizing machinery that they love but it has to be embedded the larger evolutionary framework.

DSW: As you know, one of the strongest challenge to orthodox economics has come from behavioral economists such as Richard H. Thaler and Cass R. Sunstein, who call for an economic theory based on “Homo sapiens, not Homo economicus” in their book Nudge. Yet, in my own opinion, the field of behavioral economics falls far short of the fully rounded evolutionary approach that you provide in The Secret of Our Success. How would you distinguish your paradigm from the field of behavioral economics in its current form?

JH: I see two problems with behavioral economics at least as you just framed it. The first problem is that many behavioral economists haven’t fully confronted what I call the WEIRD People problem.(Western, Educated, Industrialized, Rich and Democratic) Researchers often think they’re studying “Homo sapiens“, but actually they’re studying a particularly peculiar form of cultural psychology. This is because, until recently, most studies have been done with WEIRD undergraduates. But, it turns out when placed in cross-cultural perspective WEIRD undergraduates are psychologically rather unusual and a really poor model for our species psychology. This remains a problem but I think economists are now tackling it more quickly and efficiently than anyone else.

The second problem is that most behavioral economists, like most psychologists, still think in proximate terms. That is, they don’t think about where aspects of psychology including preferences and beliefs come from. One needs a generative theory that aims to explain how and why particular aspects of psychology emerge. If you don’t have an ultimate theory about where these aspects of psychology come from you end up with a disorganized mess of heuristics, biases and preferences, which is what I see when I look much of this literature. Without a theory there’s nothing to discipline and organize the empirical research.

These two problems bring us back to where I was on your last question. Economics needs a broad evolutionary framework that allows theorists to endogenize preferences, beliefs and potentially other aspects of psychology. Then, utility functions and decision-making rules can be embedded within this larger framework.

I’m hopeful on this front. I see economists like Tim Besley at the LSE gradually taking up the cultural evolutionary framework and building a synthesis with existing tools from economics.

DSW: Great! Next, some economists have embraced evolutionary concepts on their own, starting with Thorstein Veblen, who famously posed the question “Why is Economics not an Evolutionary Science?” in an article written in 1898. Other notables include Joseph Schumpeter, R. Nelson and Sidney G. Winter, and Friedrich Hayek. How do these home grown efforts compare with your paradigm?

JH: I think all of this work connects in a variety of ways with the work I’ve been doing on cultural evolution. Certainly, Hayek, Schumpeter, Nelson, and Winter all recognize the importance of intergroup competition — what some call cultural group selection — on cultural evolution. Obviously, I think we’ve gone much further then these guys did in building a genetic evolutionary foundation, exploring how genetic evolution gives rise to cultural evolution and how this feedbacks on genetic evolution, and on building the relevant theoretical and empirical frameworks for modeling cultural evolution and measuring psychological/cultural variation.

Nevertheless, as an anthropologist I recognize the importance of connecting with powerful ancestors.

DSW: All of this has been very helpful. Among contemporary economists—by which I mean people with economic training who work in economics departments—who do you regard as most in tune with modern evolutionary theory in relation to human affairs?

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JH: that’s a great question. I’m seeing so many excellent economists engaging evolutionary theory in many different ways, from geno-economics and cooperation to cultural evolution and institutions, I don’t think I can pick just a few.

DSW: I can’t resist asking you to compare your paradigm with one more academic discipline—Sociocultural Anthropology. Defined in terms of subject matter, you are a sociocultural anthropologist, but most people within the discipline wouldn’t see it that way and some wouldn’t even want you in the same department as them. Please explain.

JH: The academic discipline of anthropology is split by the fault line that separates science and humanities. In these border regions, many in humanities reject all systematic scientific efforts to understand humans and see the application of evolutionary theory to understanding humans somewhere between off-base and immoral. Since my earliest work in graduate school I’ve used “the three E’s”: Evolution, Equations and Experiments. These were all big no-no’s for a cultural anthropologist, since they represented efforts to quantify, measure and explain. It’s hard for people outside of humanities to understand this but there is a strong distaste bordering on contempt within at least parts of the humanities for these sorts of scientific endeavors.

Nevertheless, I’m sensing that times are changing. When I started, anthropologists never used behavioral economic experiments. Now, it’s not uncommon to see behavioral economics experiments in the journal Current Anthropology. Moreover, the list of anthropologists, especially young ones, interested in learning about experiments, cultural evolution and quantitative ethnographic methods seems to be growing. Perhaps the field is beginning to move towards us.

I should say that I still consider old-fashioned, qualitative field ethnography to be one of the main tools in my toolbox. I’m still inspired theoretically by my experiences doing fieldwork in the Peruvian Amazon, rural Chile, and the South Pacific.

My book is filled with snippets of ethnography that enrich, and round out, the quantitative data that underpins many of my conclusions. There’s nothing incompatible about doing rich and textured anthropological ethnography while at the same time conducting carefully controlled experiments. All of these contribute to a deeper understanding of the phenomenon under investigation. This has always seemed completely obvious to me since my earliest days of graduate school. So it’s always puzzled me why it’s not so obvious so many other researchers.

DSW: In my book Evolution for Everyone, I say that the Ivory Tower is more aptly called the Ivory Archipelago—many islands of thought with little communication among islands—and that evolutionary theory can be used as a common theoretical language to create the United Ivory Archipelago. Your book provides a great example of conceptual integration, allowing you to weave examples from dozens of academic disciplines—from cultural anthropology to neurobiology—into a single story. Our interview highlights the continuing need for academic integration, even for “islands” as nearby as evolutionary psychology, behavioral economics, and evolutionary economics. I would like to end our interview on a more practical note. How can the new and more integrated worldview that your book represents be used to address real-world policy issues at scales both small (e.g., urban neighborhoods) and large (e.g., income inequality and climate change)? I realize that this is a hopelessly broad question to end with, but anything you can say about the practical application of your paradigm would be appreciated.

JH: All approaches to explaining human behavior, implicitly or explicitly, involve assumptions about human nature. I like to think my main contribution is working towards building a better theory of human nature that can then be used to underpin work on policy. In the final chapter of my book I list a series of features of human psychology and behavior that emerge from the gene – culture coevolutionary approach I develop in the book. I hope this enriches our understanding of human nature in ways that could prove useful for policymakers.

DSW: Thanks very much for taking the time for this interview! As part of the older generation of evolutionists that includes Pete Richerson and Rob Boyd, it’s a pleasure to see the next generation that you represent accomplishing so much and succeeding so well.

JH: Thanks David—great to be with you!

2o16 July 12