The role of social reinforcement in norm transmission and cultural evolution

Abstract

Work on cultural evolution, especially that of Boyd, Richerson, and Henrich, has said little about the role of reinforcement in cultural learning. This is surprising, for reinforcement is an old system, it is found across a diverse array of organisms, and it is a successful concept in various scientific disciplines. The main claim of this paper is that social forms of reinforcement play a role in cultural evolution. More specifically, I argue that starting early in human history, social approval and disapproval of behavior function as reinforcers and punishers; approval and disapproval thereby start a process whereby norms are transmitted. After giving arguments for these claims, I discuss work on social learning strategies—cultural rules specifying who to learn from and how to learn from them (Heyes in Philos Trans R Soc 371(1693):1–8, 2016. https://doi.org/10.1098/rstb.2015.0369). I suggest that the account I develop here can help explain the connection between these learning rules and cultural evolution. I illustrate this point with recent work on divination practices (Hong and Henrich in Hum Nat 32:622–651, 2021. https://doi.org/10.1007/s12110-021-09408-6). My account proposes that forms of social reinforcement can explain the spread and persistence of divination practices. Besides addressing the central question (a role for reinforcement in cultural evolution), my account indirectly touches on developing themes in cultural evolution, namely, normative psychology (Heyes in Perspect Psychol Sci, 2023; Birch Biol Philos 36:4, 2021. https://doi.org/10.1007/s10539-020-09777-9).

Introduction

The main claim of this paper is that social forms of reinforcement play a role in cultural evolution. More specifically, I argue that starting early in human history, social approval and disapproval of behavior functioned as reinforcement and punishment; approval and disapproval thereby start a process whereby norms are transmitted (I’ll understand norms in a minimal sense: as a regularity in behavior. See the section titled “A social reinforcement account of norm transmission in cultural evolution”). The importance of the main claim is that evolutionary theorists have not said much about the role of reinforcement in cultural evolution.¹ Here, I consider four reasons we have for expecting that reinforcement plays a role in cultural evolution, and then I provide a brief layout of the rest of the paper.

First, since reinforcement learning—i.e., the process by which certain events (called rewards and punishers) influence the probability that a behavior will reoccur—is found in various non-human organisms, we have reason to believe that it is an old system. So, we can expect that reinforcement was present from the start of hominin evolution. And the earlier reinforcement appears in history, the more time evolution has to creatively work and innovate. Second, we have strong theoretical grounds for expecting that reinforcement plays a role in cultural evolution. One source of evidence is the various models of the evolution of signaling systems that assume reinforcement (see LaCroix 2020; Skyrms 2010 for an overview). Another source of evidence comes from the success of “reinforcement” as a concept in neuroscience, psychology, engineering, and related fields. We should be surprised if reinforcement didn’t play a role in cultural evolution.²

Third, if we can appeal to reinforcement to explain the transmission of cultural norms, then we can see one way by which the cultural evolution of norms begins and how cultural learning increases in importance without relying on special adaptations dedicated to or evolved for norm transmission. Various authors hold that humans have genetically based adaptations specialized for culture (e.g., Richardson and Boyd 2004; Henrich 2016; Tomasello 2014). A main challenge for this approach is to explain how cultural learning becomes important enough for evolution to select for genetically inherited capacities for cultural learning. My claim is that reinforcement can explain the transmission of norms without relying on specialized adaptations.³

Fourth, Birch (2021) argues that the evolution of normative cognition began with cognitive adaptations for representing standards in practice and skill.⁴ Reinforcement can supplement this account if reinforcement can be used to explain standards implicit in human practice and skill. So, to summarize, we are confident that reinforcement was an early evolutionary resource. Appealing to reinforcement in cultural evolutionary theory has strong theoretical support, and doing so has various theoretical benefits.

I will now outline the rest of the paper. “A brief discussion on cultural evolution” section sets the context of the paper. In “A social reinforcement account of norm transmission in cultural evolution” section, I defend my main claim, namely, that social forms of reinforcement play a role in cultural evolution. I provide a how-possibly account whereby approval and disapproval function as reinforcers and punishers, and this allows for early normative behavior. I also propose a process by which we become reinforceable by approval and disapproval, and I suggest that this process can be the target of selection. In “Evolution, Suadens reinforcement, and social learning strategies” section, I explain how my account of social reinforcement can explain an important kind of rule based social learning strategy; I thereby make a close connection between these social learning strategies and cultural evolution. As an example, I introduce the case of divination practices.

A brief discussion on cultural evolution

I will work within what is commonly referred to as the “California school.” This includes the work of Boyd, Richerson, Henrich and their collaborators. I don’t give any argument that this is the correct or complete characterization of the theory of “cultural evolution.” I am simply interested in working out a view from this perspective and in contributing to this tradition.

How can I be said to contribute to this tradition? I wrote in the introduction that we have strong reasons to expect reinforcement to play a role in cultural evolution, but its role is underdeveloped (or neglected) in the California school. One of the reasons that reinforcement may not play a larger role in their theories is that reinforcement is a typically understood as a mechanism of individual learning; it is thereby seen as a costly form of learning. A key theme of Boyd and Richerson’s (1985) formal models is that different forms of learning (e.g., individual vs cultural) have different associated costs. They thereby conclude that evolution selects for different forms of learning. It selects for cultural learning when it is less costly than individual learning. In “A social reinforcement account of norm transmission in cultural evolution” section, I argue that social forms of reinforcement can be sufficiently low cost. Following Boyd and Richerson’s underlying logic, I conclude that evolution would have selected for these social forms of learning.⁵

Lastly, I should note the differences between my account and that of Castro et al.’s work on the role of approval in cultural evolution (2010, 2022). I agree with these authors that approval and disapproval constitute a cultural inheritance system, that reinforcement is the framework to understand how approval and disapproval function in cultural evolution, and that such account helps explain the origins of normativity (Castro and Toro 2022; Castro et al. 2021).⁶ But here provide distinct arguments for these claims.

General aspects of selection: variation, replication, and differential success

In what follows, I will focus on three aspects of evolution by natural selection commonly known as Lewontin (1970) conditions: variation, transmission, and differential success. It’s important to note that the discussion in this section is not meant argue that cultural evolution is selectionist. I am using these concepts to frame the discussion. I will say about more about cultural evolution and selection in “Selection and reinforcement via approval” section.

Different views on transmission, variation, and differential success

Within cultural evolutionary theory, theorists differ on what causes and constitutes variation, transmission, and differential success. I start with the question, “what varies?” The cultural entities that Henrich (2016) discusses include practices, norms, and representations.

Heyes (2018a) argues that cultural evolution can also explain cognitive capacities, not just cultural products.⁷ Given a genetic starting kit (social motivation and tolerance, low specificity attentional biases, and domain general cognitive processes, e.g., associative learning), Heyes argues that we can explain the development of various cognitive capacities such as imitation, mind reading, and language.⁸ My account is like Henrich’s in that I focus on norms. However, my account is like Heyes’s in that it appeals to domain a general mechanism, i.e., reinforcement. Furthermore, my account is unlike Henrich’s (2016) in that I don’t require a cognitive mechanism dedicated and evolved for cultural learning. Henrich has argued that we are genetically predisposed to be norm following creatures. My view proposes that norm following begins with reinforcement.

Next, what are the causes of variation in cultural evolution? Two sources of cultural variation are imperfect transmission of cultural information and haphazard discovery (Henrich and Boyd 2002). For example, Henrich (2016) writes that given enough time, an individual can accidently discover a slightly new but useful variation on a practice or tool use. By multiplying the number of individuals and the amount of time, we greatly increase the probability of a member of a population “coming across” advantageous practices and tools. Similarly, Sterelny (2012) appeals to populational and demographic features.⁹ A larger population is better able to support specialists. Specialists are more likely to innovate. I draw on these ideas and apply them to norms. Useful norms are discovered accidentally and on the basis of demography.

Besides differences regarding what varies, theorists disagree on how culture is transmitted. One mainstream view, championed by Richardson and Boyd (2004) and Henrich (2016), posits genetically inherited learning tendencies that predispose an individual to copy some agents more than others.¹⁰ These include preferentially attending to cues related to prestige, success, sex, or age. In “A social reinforcement account of norm transmission in cultural evolution” section, I argue that reinforcement can explain the transmission of norms. Lastly, let’s turn to differential success. The idea behind differential success is that some cultural entities contribute, and some do not contribute, evolutionary benefits.¹¹ Those practices that do not contribute eventually “die” out.

A social reinforcement account of norm transmission in cultural evolution

In this section, I argue that social forms of reinforcement can play a role in cultural evolution. The role they play is that approval and disapproval are mechanisms of norm transmission. “Reinforcement and norm transmission” section elaborates on this claim and gives two arguments in favor. Next, I suggest that to be good arguments, something like the following must be true. (1) Some evolutionarily beneficial norms can emerge as a byproduct of minimally cooperative group life, and (2) incentives are somewhat aligned in those forms of group life. I close by drawing out reasons for both claims. The account so far is consistent with various explanations of how we come to be reinforced by approval. But in “Selection and reinforcement via approval” section, I propose a three-part process by which domain general learning mechanisms, along with the appropriate interaction with the social-cultural environment, explain the fact that we are reinforced by approval. Moreover, I suggest that this process can be the target of selection insofar as facts about what is a reinforcer for an organism are the target of selection.

Reinforcement and norm transmission

My account of reinforcement as a mechanism of norm transmission in cultural evolutionary theory is inspired by Baum’s (2017, 1995) behaviorist account of rule giving and following. However, I am not a behaviorist. And, for it to apply as far as possible into the evolutionary past, my account does not assume complex forms of language.¹² So, my views will look different and be argued for differently. I’ll think of normative claims as emerging at a proto-linguistic level. Here, agents might express various forms of approbation and disapprobation—e.g., grunts or cries. In turn, these expressions influence the behaviors of others, and this begins the emergence and evolution of norms (or proto-norms). Some might think that, at this level, we have neither “claims” nor something “normative.” That is fine. On my account, it is approbation and disapprobation that does causal work—it is what reinforces norms. By a norm, I will just mean a standard or a rule describing a behavioral regularity, and these needn’t be linguistically represented.¹³ That said, I intend this as an account that can scale up along with complex forms of language. One way this can occur is that language allows agents to make explicit what occurs, what is expected to occur, what one’s values and commitments are, and so forth. Another way is that linguistically representation of values allows for new values or forms of valuation because linguistic structures support new inferences.

All of this raises a fundamental question. Why should we expect, from an evolutionary point of view, that approval and disapproval relate to reinforcement and norm transmission? Here I provide two answers. One answer is that approval as a reinforcer is an efficient learning mechanism when compared to learning solely by the consequences of one’s actions. The non-social consequences of one’s actions can be costly or lethal, such as when one consumes a poisonous mushroom or explores unfamiliar territories. Also, it can be difficult to discern what such consequences are because cause and effect don’t always occur simultaneously and because various other putative causes will be available. Difficulties associated with learning via non-social consequences can be understood as cost problems. Learning by direct experience that a mushroom is poisonous costs one’s life. Figuring out which techniques best help produce crops costs years of one’s life. These factors make the consequences of one’s actions into imperfect reinforcers and punishers. Now, approval and disapproval regarding our actions can help avoid these costs. First, they reduce the lethality cost. A scolded child may experience emotional pain, but they learn to not to eat a poisonous mushroom. Next, as noted, it is difficult to learn from one’s mistakes when the feedback is far removed from one’s actions. Approval and disapproval are easily paired with one’s actions, so they provide immediate feedback. Suppose that my crop fails next year. Was that because of my technique, the seed, soil, weather, or none of these? A knowledgeable person can simply express their dissatisfaction with my technique as I am performing it.¹⁴

A central idea in Boyd and Richerson’s (1985) cultural evolutionary theory is that, sometimes, evolution will favor shortcuts to individual learning because individual learning, however reliable, comes with costs. Their formal models investigate conditions when evolution will favor forms of learning that avoid these costs. My first argument in favor of approval as a reinforcer is in line with their basic logic, but it does suggest a slight correction. Boyd and Richerson (1985) seem to have too quickly dismissed reinforcement as too costly on the basis that, when used as a mechanism for individual learning, it is too costly. My first argument suggests that reinforcement via social sources is in fact low cost, despite being a mechanism typically used for individual learning.

A second answer for why approval should be reinforcing is that receiving social approval has evolutionarily beneficial outcomes. If so, then evolution probably selected for humans tuned to social approval. One reason that approval is important is because it improves and maintains our relationships. As Henrich puts it:

…Reputation itself is merely a type of cultural information…. Once our ancestors could learn from each other, say about which foods to eat or how to make a tool, we could also learn from each other about whom not to build a long-term relationship with for activities like hunting, sharing, mating, and raiding… (144)

A good reputation depends on the approval others have towards one’s characteristics, personality, tendencies, and so forth. Early human life gave a lot of importance to social capital (e.g., reputation) over material capital since there is less of the latter. In mobile foraging societies, people have fewer possessions because they can carry less as they move. One’s reputation might be one’s most valuable asset simply because it is one’s only asset. Even if a society is no longer mobile, or if it is only partly mobile, their economy hasn’t scaled up to the level of modern times; thus, many individuals cannot easily offset losses in social capital by drawing on material wealth. In modern society, money can replace a lot of the need for approval or reputation. A person can pay for childcare, transportation, or food without anyone knowing anything about his or her moral character. But even here there are limits: we easily take our businesses elsewhere if we don’t like the way we are treated.

At this point, we should address a possible suspicion that my arguments assume something crucial, such as norms or a mechanism ensuring the reliability of other agents. For example, in my second argument, we should not imagine an agent entering a vibrant community and needing to be accepted. A vibrant community may have practices of hunting, foraging, resources distribution, and so forth. This certainly is a situation where the approval of others pays off, but that is partly because there are already various norms in place. Where did these norms come from? In a similar manner, we need to be careful about how we imagine my first argument. There, I explained that signals of approval and disapproval meet low-cost requirements of learning. Parents tell children not to eat poisonous mushrooms. Someone scolds me for poor farming technique. A question emerges: how do I know that the farmer wants to teach me instead of deceive me? If our interests are aligned, then I can trust the farmer. What mechanisms ensure that our interests are aligned? At the start, I maintained that one of the attractions of reinforcement-based explanation in cultural evolutionary theory is that reinforcement has been around for a long time. We can thus reasonably expect evolution to have used reinforcement. But if interests must be aligned, then we see some limits of the account. The worry is that we must first have the mechanisms that align the interests of various agents in place before reinforcement begins to work.

It seems that my arguments require something like the following: in very simple group life, (1) minimal, beneficial norms can emerge as the byproduct of agent activity in said form of life; and (2) agents’ interests are aligned, at least to some extent. Both of these help alleviate the suspicion that my account assumes that norms already exist or that some mechanism ensuring the reliability of others is already in place. For example, if (1) is true, we can posit some benefits of responding to social approval without assuming that these benefits only occur in the context of a vibrant and fully developed community. If (2) is true, then approval and disapproval can be at least somewhat reliable signals. Aligned interests function as disincentives to deceive someone. If the farmer in the above example is my father, then he is not incentivized to teach me a bad farming practice. Both (1) and (2) are plausible claims, as we can see by drawing on some work from Sterelny.

Sterelny (2021) argues that hominin lifeways were cooperative as early as 1.8 million years ago.¹⁵ One valuable insight in Sterelny’s work involves the distinctions between forms of cooperation and the mechanisms that support these forms. That is, there are different forms of cooperation, different mechanisms supporting these forms, and different ways these interact. Increasing levels of cooperative complexity require increasingly complex mechanisms stabilizing cooperation. Cooperation is destabilized by free riders and those who steal the profits of cooperation, which Sterelny refers to as bullies. The more complex the form of cooperation, the harder it is to deter free riders and bullies. But, Sterelny maintains, early forms of hominin cooperation were simple enough to solve the free rider and bully problem.

One example of said form of early cooperation is collective hunting. In collective hunting, everyone who participates is present, so reciprocation is not required. Anyone who takes more than a fair share will be seen by everyone. Everyone is interested in sanctioning the cheater. So, recruiting third party support to sanction cheaters is not needed. Moreover, Sterelny’s account maintains that these early lifeways were egalitarian. Dominance hierarchies, or bullies and free riders, faced the development of weapons. In non-human animal societies, dominance depends on the strength of the individual. Weapons challenge power-based hierarchies. Specifically, weapons play this role when collectives are not yet large and complex enough to form a class with weapons dominating another class.

The relevance of Sterelny’s account is that it gives us an early, simple form of cooperation where interests are minimally aligned, and norms begin emerging as a byproduct of simple group life. Consider a simple norm such as, “don’t take more than your fair share.”¹⁶ If an agent lives in the world as Sterelny describes it, taking more than one’s fair share can cause resentment. At best, one is excluded from collective hunting. At worst, one is attacked with weapons. It is certainly in the interest of parents to approve of fair sharing behavior in their children and to disapprove of unfair sharing behavior, and it is in the interest of children to respond to their parent’s attitudes. If children learn to share fairly, members of the hunt benefit for at least two reasons. First, the resources were zero-sum. Second, sanctioning group members comes with costs. For example, excluding a member from a collective hunt means there is one less team member. In this way, community members come to have an interest in the early education of children. If they don’t intervene directly in children’s learning via approval and disapproval, they may intervene indirectly by disapproving of parents who don’t themselves intervene in the child’s learning. Thus, if Sterelny’s account is correct, then we can meet the two requirements. Norm governed lifeways can begin to emerge early in hominin evolution. That is, it can occur as early as the just described basic forms of cooperation evolve. On Sterelny’s view, this is almost two million years ago. It is difficult to make judgements about what could have happened in millions of years. But we can put this in perspective by noting that the account I’ve been developing is plausible at the early stages of hominin evolution. The model also suggests a way forward in cultural evolution. I mentioned above that, as cooperation increases in complexity, we need new mechanisms to solve for cheating and defection. If normative life can begin in minimal forms of cooperation, we get the chance that norms for more complex forms of cooperation evolve.

Selection and reinforcement via approval

This sub-section develops the idea of a reinforcement profile, and it draws its connection to selection and social-cultural learning. Reinforcement profiles are facts about what is a reinforcer or punisher for an organism. Reinforcement profiles are targets of selection insofar as they vary, are transmitted, and are differentially successful. One way of understanding reinforcement profiles is that they are based on evaluative criteria. Evaluative criteria are standards an organism “uses” for adopting behaviors. Where do these standards come from? A common view is that humans are innately or genetically predisposed to value approval from social sources. While my account in “Reinforcement and norm transmission” section is consistent with this view, here I propose an alternative whereby approval is intrinsically valued (as opposed to instrumentally valued), but this value is not innate or genetically inherited. With the help of social sources, the value of approval is learned via secondary reinforcement. According to this proposal, there are rich correlations between the internal states of others (especially caregivers) and effects on oneself. Human, domain general mechanisms learn these correlations. Humans thereby begin using the internal states of others as their own evaluative criteria. The result is a reinforcement profile; humans become reinforceable or punishable by the approval or disapproval of others.

Putting this together, insofar as reinforcement profiles are targets of selection, and social reinforcement is the result of a social-cultural process, I suggest that this social form of reinforcement is the result of a cultural-selectionist process.

My first task is to develop the concept of a reinforcement profile. To do so, we will need only a few minimal or core concepts. These minimal concepts are borrowed from the behaviorist tradition, but nothing here depends on behaviorism (Baum 2017). The starting point is the assumption that behaviors, in a context, have regular consequences. Some of those consequences make a behavior more likely to reoccur. These are called “reinforcers.” Other consequences make the behavior less likely to reoccur. These are called “punishers.” To illustrate, each time Maria has asked her grandmother for candy, she has gotten candy. So, the next time she sees her grandmother, she will ask her for candy. Here, her grandmother’s proximity is the context. The behavior is asking for candy, and receiving candy is the reinforcer. Lastly, and this is the part that ties back to evolution, the reinforcers are reinforcers because they in general lead to evolutionarily beneficial outcomes, and the punishers are punishers because they in general lead to evolutionarily bad outcomes.

What do I mean by the statement, “reinforcers are reinforcers because they in general lead to evolutionary beneficial outcomes?” To explain what I mean, let me ask a question.¹⁷ Why is candy a reinforcer for Maria? A reinforcer can be broken down into two kinds: proximate and ultimate. The proximate reinforcer is the immediate consequence that reinforces the behavior. It is the sweetness of Maria’s candy. The ultimate reinforcer is something that explains why the proximate reinforcer exists. Sugar is a reinforcer for humans because it gives humans energy, hence contributing to their survival (within a limit). Ultimate reinforcers can be identified with Baum’s (2017) “HRRR” acronym: health, resources, relationships, and reproduction. So, we can form the question in a more general manner. “Why does candy reinforce Maria’s behavior?” can be phrased as “why is candy a proximate reinforcer?” Abstracting even more, “why is a particular consequence a proximate reinforcer for a given organism?” Let’s call the facts about what proximately reinforces an organism’s behavior its reinforcement profile. The question could thus be, “why does an organism have the reinforcement profile that it does?”.

An evolutionary answer is that different reinforcement profiles will have different consequences—different regarding their HRRR properties. For example, an organism with a reinforcement profile that reinforces food producing behaviors will end up with more energy resources than an organism without it. What this suggests is that reinforcement profiles are the targets of selection. Recall, selection requires three ingredients: variation, replication, differential success. Here, the reinforcement profiles vary, are replicated, and succeed depending on the HRRR-properties of their consequences.

In what follows, I’ll understand reinforcement profiles as based on, or describable as, evaluative criteria. Evaluative criteria are rules or standards that function as criteria for adopting or rejecting a behavior. For example, a rat may discover that licking the nozzle of a water bottle produces water. The feeling of satisfaction following the drinking of water can be described as the guiding criteria for future decisions to drink from the water bottle.

How does an organism acquire its reinforcement profile, i.e., its evaluative criteria? A long-standing answer comes from biological evolution: an organism genetically inherits a reinforcement profile that is the result of evolutionary history. Is there an analogue in cultural evolution? I answer affirmatively. Castro and Toro (1995, 2004, 2010) have argued that human social learning contains the ability to acquire evaluative criteria via social sources of approval and disapproval. I am in agreement, but my precise question is, “why do approval and disapproval function as reinforcers and punishers?” If they function as reinforcers and punishers, then approval and disapproval are part of our reinforcement profile. What is the explanation for this fact? Castro and Toro seem to base this reinforcement profile on a specialized adaptation for social approval. By contrast, I propose a three-part account of how this social aspect of our reinforcement profiles can be acquired without assuming a genetically specialized adaptation.

Here is my three-part outline. First, there are rich correlations between the emotional states of caregivers (or of signs of their emotional states) and the experiences of dependents.¹⁸ Prenatally, a mother’s emotional state will correlate with various biochemical states (e.g., dopamine, stress hormones, nutrients, or blood pressure) that will affect the fetus. Postnatally, caregivers are sources of food, touch, kind gestures, warmth, nutrition, and so forth. But when upset, they can be sources of noxious stimuli such as loud verbal sounds. Secondly, early in development, humans have sufficiently robust learning mechanisms–sufficient enough to begin learning about these correlations. Of course, these learning mechanisms take a long time to mature (Sydnor et al. 2021), but the point is that learning begins early even if full maturation comes later. Third, just as humans use their experiences to evaluate events, humans come to use the experiences of their caregivers to evaluate events (Joiner et al. 2017; Borsa et al. 2019). To see this point, consider the following question. How do we learn that chocolate is good and burns are bad? Well, one day we tasted chocolate and that produced a pleasurable sensation. Another day we touched a flame, and it produced a terrible sensation. We came to associate one stimulus with another. As with the chocolate and the fire, the child learns that the emotional states of a parent are correlated with (causally implicated in) their own emotional states. Chocolate and happy parents are good. Fire and angry parents are bad. Why? The former produces pleasure and the latter displeasure.¹⁹ My proposal is that the value of approval from others can be learned and valued intrinsically.

It will be useful to have a name for the type of reinforcement profile that we have been discussing. Borrowing from Castro and Toro, let’s call this type of reinforcement “suadens reinforcement.” Suadens comes from the Latin word suadeo, which means to approve or value.

Let’s put together the main ideas of this sub-section. The first key idea is that selection can target reinforcement profiles. Different profiles have different HRRR consequences, and selection plays a role here because of these differences. The second key idea of this sub-section is that suadens reinforcement is part of human reinforcement profiles; we acquire suadens reinforcement via social-cultural sources. These two ideas suggest that suadens reinforcement is the result of a (cultural) selectionist process.

To be clear, this last suggestion is contended by various authors who question whether cultural evolution is a genuinely selectionist process (e.g., Chellappoo 2022; Lewens 2002, 2015; Sperber 2000). I mean my proposal—that suadens reinforcement is the result of cultural selection—as a way of understanding the emergence of suadens reinforcement; this is not meant as an argument that would answer all relevant doubts on cultural selection. Those who are skeptical of cultural selection may read the rest of this paper and focus only on the main claims. For example, in the next section, I suggest that social learning strategies are the result of cultural selection insofar as they are accounted by a reinforcement profile that is itself the result of cultural selection. The main claim here is that these learning strategies can be transmitted via social forms of reinforcement. Readers who are skeptical that cultural evolution is selectionist in this regard can read me as saying “if cultural selection explains our social reinforcement profiles, then it explains social learning strategies. It does so indirectly.” Critics can reject the antecedent and still endorse my main claim.

Evolution, Suadens reinforcement, and social learning strategies

In the previous section, I provided a cultural evolutionary account of norms. Here, I propose that this account can help explain rule based social learning strategies. I also propose that these rule based social learning strategies have a cultural selectionist basis: they are the result of cultural selection insofar as they are supported by a reinforcement profile that itself is the result of cultural learning and selection. The value of this contribution can be seen by situating it within the work of Cecilia Heyes, so I will start there. Then, “The Case of Divination” section provides an example.

There are two broad (non-exhaustive) ways of characterizing Cecilia Heyes’ work on cultural evolution. One is the proposal and theory of “cultural evolutionary psychology” or “cognitive gadgets” (Heyes 2018a, 2023). Another is the idea of culture-culture coevolution (Birch and Heyes 2021). The former is a research program and theory according to which various human-cognitive mechanisms are the result of cultural evolution. The latter is a model attempting to describe the emergence, development, and distinctiveness of human culture. For both projects, the concepts of social learning strategies and explicit learning biases are central. I’ll briefly outline these concepts and explain how my account can illuminate the evolutionary basis of selective social learning strategies.

Heyes (2016, 2018a) points out that, as researchers use the term, “social learning strategies” refers to a diverse array of learning phenomena that is found in insects, fish, birds, and primates. The core idea is that an organism’s behavior is influenced by the information it gathers from conspecifics. Heyes believes that selectivity makes human social learning strategies distinctive. Selectivity refers to the tendency of acting on or learning from one source of information over the other. There are at least two possible explanations of selectivity. On the strategic view, conscious, explicit, and domain specific rules make human social learning selective. Heyes gives the example of the rule “follow digital natives” (people born during the digital age) when learning about new technology. On another view, called the attentional view, domain general cognitive processes make social learning selective. The idea is that domain general, individual learning (such as that based on associative mechanisms) influences attention. In turn, attention influences what is learned and who one learns from simply because one is paying more attention to some agents over others. Heyes maintains that for the most part, the attentional view is correct. Social learning is selective in both humans and non-humans via domain general, attention directing mechanisms. However, Heyes also thinks that the strategic view is sometimes right; the strategic view explains the distinctiveness of human social learning. These rules make human social learning distinctive because they accumulate the experience of many agents, improve fidelity in learning, and contribute to variation. I’ll refer to strategic social learning strategies as SSSs.²⁰

It is worth comparing SSSs with explicit learning biases as discussed by Birch and Heyes (2021). We can read these authors as proposing a broader empirical model. Their account begins with the divergence from great apes about 6 million years ago. Early human social learning was based on domain general mechanisms. Agents could thereby acquire knowledge and skills from conspecifics (mostly parents). In a later stage, humans began using their cognitive-representational abilities to pass on “explicit learning biases,” which are types of human SSSs in our terminology.²¹ These have the previously mentioned benefits (e.g., high fidelity transmission), but Birch and Heyes add something, namely, there is “…more to gain from investing effort in copying the specific technique of a specific individual, rather than hedging [one’s] bets and learning from as many different models as possible.”²² Explicit learning biases help begin a feedback loop by getting agents to choose between groups. As more successful groups attract more agents, they increase their chances of success, which in turn attracts more agents.

One question emerges from the discussion on SSSs or explicit learning biases, namely, “how are SSSs the result of cultural evolution?” For example, Heyes (2018a, 2018b) does not tell us how selective SSSs, which are conscious, explicit, and reportable rules, are the product of cultural evolution. Heyes may be read as inferring from these features that, plausibly, they are the result of cultural evolution instead of, say, genetic evolution or design. Even so, it is important to search for a how account (even if it’s a how-possibly account) because, otherwise, it isn’t entirely obvious how cultural evolutionary theory can explain these types of SSSs (Cao 2020). To illustrate my point, consider Heyes’ example of “copy digital natives.” It is not obvious why cultural evolutionary theory should be invoked to explain this type of strategy.²³ Why do we need cultural evolutionary theory to explain how one learns to use modern technology?

Birch and Heyes (2021) view is that explicit learning biases play a role in cultural evolution; that is, they form part of the feedback loop mentioned earlier. On their view, one form of cultural fitness (what they call CS2) is understood as the number of models an agent or group acquires. Certainly, this gives SSSs a role to play in cultural evolution, but it leaves open the question of how (if at all) they are the result of evolution or selection. The views I developed in “Reinforcement and norm transmission” and “Selection and reinforcement via approval” sections make two proposals.²⁴ First, SSSs are a type of norm that is transmitted via approval and disapproval; they are based on a kind of suadens reinforcement.²⁵ Second, these learning strategies are the result of evolution or selection insofar as our reinforcement profiles are the result of evolution or selection. In the next sub-section, I will provide a discussion on divination practices as an example of these ideas.

The case of divination

Heyes (2023) has recently argued for a reevaluation of the idea that humans genetically inherit cognitive and motivational mechanisms specialized for normative life. There are many ways to reevaluate that idea, but the way I do so here is by giving internal norm representation and motivation a relatively diminished role. The picture here is one where norms are motivated by the approval and disapproval of social sources. In important ways, the norms are externally represented by the reoccurring behavior of others, the practices of a culture, and its traditions.²⁶ I will discuss divination practices as an extended example. I’ll say why I understand divination practices as a kind of SSSs, and I argue that these can be explained by social reinforcement.

The earliest hominins inhabited a dynamic and complex world that they knew very little about. They began with only general-purpose learning mechanisms similar to those of other species (see “Evolution, Suadens reinforcement, and social learning strategies” section). Many animals do quite well with this much. They can learn regularities and predictive relationships between various stimuli. However, these mechanisms are imperfect or insufficient to explain the diversity of human behavior. This is one key insight from Boyd and Richerson (1985) as well as Henrich (2016).

Henrich (2016) conjectures that divination practices evolved to counterbalance our (sometimes imperfect) modes of reasoning.²⁷ In one example, the Kantus of Kalimantan use bird augury to choose where to sow. Henrich explains that this practice randomizes where one sows, and this randomization is an improvement over relying on one’s learning. First, agents have been observed to plant in areas that have recently been flooded because they mistakenly believe that a second flood is unlikely. Second, agents are likely to plant where others have had success, and this can lead to bad yields since land nutrients need time to replenish.²⁸

Hong and Henrich (2021) understand divination practices as epistemic technologies: means to discover information about the world. Then they ask, “if divination isn’t ‘real,’ then why do divination practices persist across cultures?” In answering this question, they distinguish between objective efficacy (whether divination actually works) from subjective efficacy (whether it’s perceived to work). Objective efficacy cannot easily undermine belief in divination because disconfirming evidence is ambiguous. For example, a failed divination might suggest that the ritual was done incorrectly. Several factors explain subjective efficacy. First, biases such as the availability heuristic or saliency effects make it easier to remember times when divination worked. Secondly, the testimony of others, the behavior of practitioners, and the lack of alternative options make even non-believers try divination. In turn, their participation is perceived by others as endorsement.

Altogether, we get the following view: (A) divination practices can have beneficial consequences even if their metaphysical commitments are mistaken. They function to improve action when reasoning may lead one astray. (B) Divination is used as an epistemic tool. (C) Divination practice is sustained by various factors influencing its perceived efficacy. I agree with Hong and Henrich on these points, but I propose an additional factor contributing to “perceived efficacy,” and this factor involves a distinct psychological claim. Hong and Henrich interpret the psychology of agents practicing divination as undergoing a cost benefit analysis.²⁹ Agents engage in divination because they believe it works, or because there are low costs and potential gains if it does work. My psychological explanation, based on the account from “A brief discussion on cultural evolution” section, is that the practice of divination is grounded on reinforcement principles. This can be a correct explanation even when the same practice is naturally described in cost benefit terms.³⁰ For example, Niv et al. (2002) show that reinforcement learning in bees can lead to risk averse and probability matching behavior.

In broad outline, I propose that reinforcement can play a role at the exploitation-exploration phase. At the exploitation phase, social approval increases the chances that an agent uses divination. At the exploration phase, social disapproval decreases the chances that an agent adopts alternatives to divination. Let me elaborate.

In the exploitation phase, agents engage in divination practices if those practices are sufficiently reinforcing. My claim is that since social forms of approval reinforce divination, approval can go part of the way in explaining divination; that is, they explain why agents engage in the practice (exploitation). Community members will tend to approve of those who consult divine sources. Those who cite divine sources, especially on important matters, will seem reasonable and intelligible. Appearing reasonable and intelligible is a form of receiving social approval since it is a form of social endorsement—one abides by the community’s endorsed practices.

How can we be sure that social reinforcement is strong enough to sustain cross cultural divination practices? This question is best answered by formal modeling and empirical investigation. But what has already been said can give us some confidence. Recall Hong and Henrich’s insight that disconfirming evidence is ambiguous.³¹ This can be rephrased as the claim that, in the exploitation phase, evidence against divination plays a small role in decreasing the chances that one uses divination. If social forms of reinforcement play a significant role for an agent, then it may be strong enough to encourage exploitation.³²

Next, exploration means that the agent searches a given problem space for new behaviors. If exploration is not sufficiently reinforced, then agents won’t seek new behaviors. If members of the community discourage variations from a divination practice, then this disincentivizes exploration, i.e., the search for alternatives to divination. If agents do not readily find strongly reinforcing alternatives to divination (e.g., if they don’t find something that works better), then social disapprobation of disregarding divination can sustain divination.

I interpret divination practices as a kind of SSSs. For one thing, they are rules about who to learn from, e.g., shamans. Moreover, if Henrich is correct, then divination practices are beneficial to the community even if they are mistaken about its metaphysical commitments. Community members will be interested in how one learns from divination practitioners. Some of this practice is directly recommended, as when agents explicitly recommend the practice or shun people for going against it. But it is also indirectly recommended when one sees people observing the practice, following costly or counter intuitive rituals, or collecting various symbolic materials. On this picture, internal representation of norms and internal motivations for following those norms plays a relatively diminished role. If my account is correct, then one’s culture plays an important role in representing and motivating the norms.

To conclude, the upshot here is that we have an empirically informed case where we can apply my social reinforcement account of norms to understand SSSs. In providing this example of how my account works, I’ve had to raise (without settling) difficult questions about the evolution and nature of norm representation and their motivation. On my view, these are relatively new and open questions for cultural evolutionary theorists, especially in the California school, and related areas of research (Heyes 2023).

Conclusion

The main goal of this essay is to develop a social reinforcement-based account of norm transmission in cultural evolution. My claim is that humans are sensitive to the approval and disapproval of others, and this plays an important role in the emergence and evolution of norms. To make the account vivid, I argued that it can help explain the evolutionary basis of strategic social learning strategies. I illustrated this with the account of divination. One benefit of this project is that it draws a closer connection between a theoretically successful concept (reinforcement) and cultural evolution. Moreover, the account promises to help us understand the cultural evolution of something important in everyone’s life: norms.³³