Inference and Hypothesis Testing in Cultural Evolution

This chapter demonstrates how evolutionary anthropologist Ruth Mace applauds Robert Boyd's multidisciplinary approach to the study of human evolution, while stressing her own belief in the importance of empirical testing. She points out that many questions remain about how norms arise, why they vary, “how they are maintained, and how easily they change.” In a more critical vein, Mace suggests that some of the behaviors that Boyd attributes to social norms and sanctions might better be explained based on individual benefits. This includes the decision to participate in warfare. Mace then describes her own empirical research on intergroup conflict in Northern Ireland and raises the question of whether “competition and conflict between groups, such as interethnic warfare, leads to parochial altruism (that is, altruism directed only within the group).”

Introduction

This introductory chapter provides an overview of professor Robert Boyd's approach to the study of human evolution that focuses on the population dynamics of culturally transmitted information. Putting aside the more familiar question of human uniqueness, Boyd asks why humans so exceed other species when it comes to broad indices of ecological success, such as humans' ability to adapt to and thrive in such a wide variety of habitats across the globe. Humans adapt to a vast variety of changing environments not mainly by applying individual intelligence to solve problems, but rather via “cumulative cultural adaptation” and, over the longer term, Darwinian selection among cultures with different social norms and moral values. Not only are humans part of the natural world, argues Boyd, but human culture is part of the natural world. Culture makes humans “a different kind of animal,” and “culture is as much a part of human biology as our peculiar pelvis or the thick enamel that covers our molars.” The chapter then outlines the lectures and discussions that follow, which originated as the Tanner Lectures on Human Values at Princeton University in April of 2016, organized under the auspices of the University Center for Human Values.

Culture, Beliefs, and Decisions

This concluding chapter highlights Robert Boyd's reply to the commentators, in which he expresses appreciation for their thoughtful disagreements, all of which “accept the value of trying to understand how culture evolved.” Boyd notes one broad point of contention, shared by Ruth Mace, Kim Sterelny, and Paul Seabright, which is that he does not “give people enough credit for making smart, well-informed decisions.” Boyd stands his ground, arguing that individual choice matters but people's basic beliefs come from their social context. With respect to the related comments by H. Allen Orr and others, Boyd expresses agreement that “cognitive abilities and cultural learning are mutually reinforcing.” Ultimately, Boyd ably defends his model against all four commentators and concludes by offering a pointed defense, against Seabright, of his own more optimistic view.

Adaption without Insight?

This chapter looks at how philosopher Kim Sterelny endorses the main contours of Robert Boyd's argument that humans are outliers in their capacity to adapt to many environments. However, Sterelny asks whether Boyd goes too far in reducing the role of “our distinctive human intelligence” in explaining humans' ecological adaptability. Sterelny at least partly defends the “library” or “Big Brain” model that Boyd argues against. Tacit, practical know-how is a form of knowledge. In addition, Sterelny contends that Boyd relies too heavily on a simple and “conformist” or “trusting social learning heuristic.” As a final point, Sterelny wonders whether and how social learning has changed across “domains and across time.”

Beyond Kith and Kin Culture and the Scale of Human Cooperation

This chapter details Robert Boyd's account of social learning and cumulative cultural evolution to illuminate how societies adapt to changing environments and develop ever more sophisticated tools and technology. Humans' ability to learn by imitation and their evolved trusting psychology are used to explain the centrality of social norms, and to explain why and how humans have for so long been “supercooperators.” Even in foraging societies, the extent of human cooperation vastly exceeds that of any other species. Ultimately, millennia of cumulative cultural evolution have helped create a vast “worldwide web of specialization and exchange.” Humans are unique in that “people cooperate in large groups of almost unrelated individuals to provide public goods.” Cooperation in large groups “requires systems of norms enforced by sanctions.” In larger and more complex societies, cooperation and the provision of public goods depend crucially on coercive sanctioning by third parties: institutions such as police and courts.

Not by Brains Alone

This chapter argues that humans make use of insights and adaptations that humans do not understand. Humans learn very often not by figuring out how things work but by imitating others who have locally useful “know-how.” The chapter then describes the conditions under which selection favors “a psychology that causes most people to adopt beliefs just because others hold those beliefs.” Indeed, it contends that “even the simplest hunter-gatherer societies depend on tools and knowledge far too complex for individuals to acquire on their own.” Ultimately, culture is the storehouse of gradually accumulated, local, and typically tacit knowledge. Thus, “cumulative cultural evolution” is the great and unique advantage of humans.

Adaptable, Cooperative, Manipulative, and Rivalrous

This chapter explores economist Paul Seabright's argument that there is a “darker dimension to what makes us human,” which Robert Boyd largely leaves aside. Human beings are the most ecologically adaptable and massively cooperative species on the planet. Seabright argues that humans are also the most spectacularly and violently competitive, and the most deviously manipulative of all species. This might seem an incoherent description, but in fact the latter qualities are deeply implicated in the former ones. It is precisely the fact of humans' extraordinary cooperativeness that allows them to create the massive resource gains that provoke their competitiveness and manipulativeness. Indeed, Seabright contends that “a much larger part of the communication that takes place around norms in most societies is about individuals manipulating other individuals” than one would think from Boyd's examples.

Imitation, Hayek, and the Significance of Cultural Learning

This chapter discusses biologist H. Allen Orr's two large and interesting questions about Robert Boyd's model of cultural learning. He wonders, first, whether Boyd exaggerates the contrast between the “Big Brain” model, which emphasizes cognitive explanations for human success, and the imitative model that Boyd prefers. Orr argues that successful imitation often requires considerable “neuronal firepower.” In addition, Orr usefully describes the partial convergence of Boyd's view with that advanced by the well-known free-market economist and social theorist Friedrich Hayek. Hayek also emphasized that social success and progress depend on the use of tacit and dispersed local knowledge, culturally transmitted social norms and ethical mores, and institutions that are the product of social evolution. Orr wonders whether scientists and social scientists pay less attention to Hayek than they should because of Hayek's politics.