Cultural group selection is a theory of cultural evolution that brings together research from such disparate fields as anthropology, behavioural economics, evolutionary biology, evolutionary game theory, sociology, and psychology. Its proponents include Robert Boyd, Herbert Gintis, Joseph Henrich, and Peter J. Richarson.

Cultural group selection is a process through which cultural groups are selected for according to the competitive advantage their cultural practices, ideas, and beliefs collectively bestow upon them. Although these cultural norms can be beneficial to the individual who holds them, they don’t have to be.[1] Norms merely have to be practiced within successful cultures for them to spread. The success of a culture can be defined by a number of things: military or economic strength, technological advancement, or the capacity to provide for a large population. Cultural norms that provide these advantages will, in turn, lead to the displacement, absorption or even extinction of other, less successful cultural groups (citation). Additionally, evidence suggests that norms will be transmitted across cultures when individuals from one culture preferentially imitate high-prestige individuals from nearby cultures (citation).

While altruistic behaviour such as kin selection and reciprocity can explain the behaviour of small social groups common in many species, it is unable to explain the large complex societies of unrelated, anonymous individuals that we see in the human species (citation). However, one of the major distinctions between humans and other species is our reliance on social learning in acquiring behaviours (citation - Henrich). These instincts allow the for the acquisition and proliferation of culture. Through cultural group selection, culturally specific cooperative behaviour can evolve to support large societies (citation). For example, in a study that spanned a variety of cultures, testing behaviour in Ultimatum, Dictator, and Third-Party Punishment games, it was found that standards of fairness and inclination to punish were correlated with both participation in world religions and market integration (citation). These differences even exist in cultures that live in the same region but have different social organization (citation).

According to Donald T. Campbell, in order for cultural group selection to occur, there must be cultural differences between groups, which can transmit across time, and which effect the persistence or proliferation of the groups. However, game theoretic models suggest that if individuals are able to migrate between groups (which is common in small-scale societies), differences between groups should be difficult to maintain (citation). Variation is maintained due to behavioral biases that enforce conformity and the emulation of prestigious members of the group. Meanwhile, the persistence and proliferation of cultures is maintained through intergroup competition and the displacement of one culture through the accelerated population growth of another culture(citation).


Mechanisms that Maintain Between-Group Variation

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Without between-group variation, cultural group selection could not occur, as there would be no group differentiation to select for. While processes such as cultural drift, epidemics, and natural disasters increase between-group variation, migration and genetic mixing decrease between-group variation while increasing within-group variation. Variation is only maintained when cultural groups have mechanisms that prevent the norms of outside groups from invading the cultural group. These ‘mechanisms’ are those uniquely human psychological traits and behaviors that encourage imitation, conformity, and in-group biases.

According to Joseph Henrich, between-group variation is maintained by the four following mechanisms:

Conformist Transmission

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Conformist transmission refers to the psychological bias to preferentially imitate high frequency behaviors in the cultural group. This homogenizes the social group and reinforces widely held cultural norms. This explains why individuals within a social group hold the same beliefs and why these beliefs persist over time. While individuals will rely on copying high frequency behaviors under various conditions, this reliance increases when an individual is exposed to ambiguous environmental or social information. (BoydRich, ellisonfud, baron) Conformist transmission can maintain between-group variation by reducing within-group variation, but it also facilitates the rapid spread of novel ideas, which increases between-group variation (Boyd and Richerson, 1985, 2002b). Taken together, reduced within-group variation and increased between-group variation lead to the cultural divergence between groups that is the driving force of cultural group selection.

Prestige-Biased and Self-Similarity Transmission

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Prestige-biased transmission is the tendency the copy those members of the group that are more successful. Preferentially copying successful members of the group allows individuals to avoid costly trial-and-error learning by imitating the better-than-average skills of the more prestigious cultural models. Individual can determine the rank of potential models by how much deference they are shown by the rest of the group. Deference is shown to high-prestige individuals to gain the opportunity to copy their successful models. We can see evidence for this bias in how new technologies, or economic practices spread to different groups according to how quick “opinion leaders” adopt them. (Roger 1995)

Meanwhile, self-similarity transmission is the tendency to copy those individuals who are similar in language, appearance, social standing and other behavioral and cultural traits. In the context of prestige-biased transmission, self-similarity means that individuals will preferentially imitate those high-prestige individuals who are similar to them. From the perspective of an imitator, this trait is adaptive. By only imitating those high-prestige individuals who are similar, the imitator avoids adopting traits or behaviors that are not compatible with his or her knowledge or social environment. (BoydRich 1987) These two social biases act together in reducing within-group variation. Additionally, prestige-biased transmission increases between-group variation by contributing to the spread of novel ideas (Boyd and Richerson, 1985, 2002b).

Punishment of Non-Conformists

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Non-conformists threaten to increase within-group variation by introducing deviant behaviors to the group and must receive costly punishment to maintain a homogenous social group. As a consequence of being punished, non-conformists will be less successful than other members of the group. Prestige-biased transmission would suggest that non-conformist behaviors would, therefore, not spread through the population. Papers on the topic suggest that this kind of punishment is prevalent across many different societies. (Sober and Wilson, 1998; Roth et al., 1991; Henrich et al., 2001; Fehr and Gächter, 2002).

Normative Conformity

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Normative conformity is the act of changing one’s visible behavior, simply to appear to match the majority, and without actually internalizing the groups opinions. This differs from conformist transmission since normative conformity does not consider that frequency of a behavior is an indicator of its worth. The Asch conformity experiments are a perfect example of how robust this effect is and it’s replication across many cultures shows that this behavior is very common. (Furnham, 1984; Neto, 1995) Henrich suggests that normative conformity may have evolved to respond to the spread of punishing behavior toward non-conformists (cite). By appearing similar to the group, one can gain the advantages of in-group membership, while also avoiding punishment. A curious byproduct of normative conformity is that it can contribute to the conformity transmission of norms that it does not hold, because they were mistakenly attributed by the imitator.

Mechanisms for Group Selection

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For cultural group selection to occur, claims Donald T. Cambell, there must be cultural differences between groups which effect their persistence or proliferation. This means groups are selected for or against according to their respective gains or losses relative to other groups.

Joseph Henrich describes three mechanisms through which this process occurs:

Demographic Swamping

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Demographic swamping occurs when one or more cultural groups reproduces individuals faster than other groups in the region because of stable, culturally transmitted ideas or practices. This is the slowest kind of cultural groups selection as it depends on natural selection of between-group cultural variation operating on a scale of millennia. It has been suggested that this is how early agriculturalist displaced hunter-gatherer societies. (Cavalli-Sforza et al., 1994; Young and Bettinger, 1992; Diamond, 1997)

Intergroup Competition

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Intergroup competition is the process by which cultural groups compete with each other over resources by engaging in warfare and raiding. The cultural practices and behavior that gives an advantage to one group over another will proliferate at the expense of those who cannot compete. There are many possible traits that could contribute to a group’s success, such as technological development, social and political organization, economic development, nationalism, etc. According to Joseph Soltis, it would 500-1000 years for group selection to happen this way.

Prestige-biased Group Selection

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In prestige-biased group selection, when individuals have opportunities to copy people from nearby groups, they will preferentially imitate the members of groups that are more cooperative than their own. Since cooperative groups have a higher average payoff than non-cooperative groups, members of cooperative groups will be considered more prestigious and worthy of imitation.


References

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  1. ^ Diamond, Jared. “The Worst Mistake in the History of the Human Race.” Discover Magazine. May. 64-66. 1987.

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