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**Author(s):** Barrett, B; Kandler, A; Aplin, L &lt;br&gt;&lt;br&gt;Cultural evolution is usually framed in terms of transmission biases or behavioral transformation via cognitive biases, although there is a third dimension that is often ignored: learning through reward. This process of internal selection that happens when socially learned behaviors are used by individuals, has been hypothesized to play a critical role in the evolution of adaptiveness of cultural traits, as they are either maintained or abandoned over the course of repeated production. To date, this has remained a verbal argument. To test this argument, we construct an agent based model where acquisition and production are linked, as acquisition is conditioned on association, as well as behavioral frequencies of associates. We show that variation in the learning rules that govern production influence the diffusion of a novel behavior. We further show that these effects can affect the inferential power of two popular models in the field of animal culture: Network Based Diffusion Analysis and Experience Weighted Attraction models. We then allow for dynamic networks of populations, and show how the social process of population turnover interacts with reinforcement learning to drive the cultural evolution of efficiency. Different regimes of population turnover generate optimal, neutral or sub-optimal selection for a more efficient behavior, when compared against static populations. These two studies generate new predictions for how reinforcement learning can influence cultural outcomes, and highlight un-discussed consequences for current practices in the field. The formulation of our model also encourages more rigorous definitions for social learning strategies and biases, as they might target the process of acquisition or production, or both, yet have been discussed interchangeably to date. They also provide theoretical support for the hypothesis that naive learners, introduced through population turnover, play a crucial role in resampling payoff landscapes.

Cultural Evolution Society 2022

The interaction of learning rules and population turnover can drive cultural evolution

cultural selection; efficiency; reinforcement learning; agent based model; social learning; social networks

### Welcome to the fourth Cultural Evolution Society Conference, CES2022! 

As last year, Underline will support the online component of the conference. The ongoing COVID-19 pandemic is causing a great deal of uncertainty for all of us. Therefore, we seek to offer a hybrid format that will hopefully allow some folks to travel to Aarhus, others to meet up locally or regionally in CES hub-lets, and other yet to participate online. The field of cultural evolution is growing in size and scope; its theories, methods and applications - both academic and applied - are getting ever more robust. Do join us in what promises to be an exciting exchange of ideas and a celebration of our field.

##### ***For SoMe interaction and live tweeting please tag @CulturalEvolSoc and use #CESconf2022***


#### The CES 2022 local organising committee
* Luseadra Joy McKerracher
* Jesper Sørensen 
* Niels Nørkjær Johannsen 
* Benjamin Grant Purzycki 
* Mette Løvschal 
* Felix Riede
* Iza Romanowska 
* Karsten Olsen

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The field of cultural evolution is growing in size and scope; its theories, methods and applications - both academic and applied - are getting ever more robust. Do join us in what promises to be an exciting exchange of ideas and a celebration of our field.

**Author(s):** Barrett, B; Kandler, A; Aplin, L Cultural evolution is usually framed in terms of transmission biases or behavioral transformation via cognitive biases, although there is a third dimension that is often ignored: learning through reward. This process of internal selection that happens when socially learned behaviors are used by individuals, has been hypothesized to play a critical role in the evolution of adaptiveness of cultural traits, as they are either maintained or abandoned over the course of repeated production. To date, this has remained a verbal argument. To test this argument, we construct an agent based model where acquisition and production are linked, as acquisition is conditioned on association, as well as behavioral frequencies of associates. We show that variation in the learning rules that govern production influence the diffusion of a novel behavior. We further show that these effects can affect the inferential power of two popular models in the field of animal culture: Network Based Diffusion Analysis and Experience Weighted Attraction models. We then allow for dynamic networks of populations, and show how the social process of population turnover interacts with reinforcement learning to drive the cultural evolution of efficiency. Different regimes of population turnover generate optimal, neutral or sub-optimal selection for a more efficient behavior, when compared against static populations. These two studies generate new predictions for how reinforcement learning can influence cultural outcomes, and highlight un-discussed consequences for current practices in the field. The formulation of our model also encourages more rigorous definitions for social learning strategies and biases, as they might target the process of acquisition or production, or both, yet have been discussed interchangeably to date. They also provide theoretical support for the hypothesis that naive learners, introduced through population turnover, play a crucial role in resampling payoff landscapes.

technical paper

**Author(s):** Micheletti, AJC & Mace, R Introduction: Most major world religions require at least some of their practitioners to commit to lifelong celibacy. A recent evolutionary model has suggested that inducing a son to become a monk can be adaptive if it increases his brothers’ reproductive success and a sociodemographic study has shown that this is the case in a Tibetan Buddhist population. However, female celibates are present in other religions and parts of the world, and it remains unclear what might drive differences in their frequency relative to male celibates. Approach: Here, we develop an evolutionary, inclusive fitness model of the coevolution of male and female lifelong celibacy. Results: We find that the frequency of monks and nuns can be influenced by how parental resources are shared among offspring and how siblings compete for them. More monks than nuns are favoured when competition is more intense between brothers than sisters, that is when resources are more important for male than female reproductive success (bride price societies). The opposite is true when competition is more intense between sisters (dowry societies). We also find a role for the extent to which brothers and sisters compete for the same pool of resources, which is influenced by cultural inheritance rules and whether wealth is mainly immovable (land) or movable (money, cattle). Moreover, the sex that disperses less is favoured to have more celibates. Discussion: These results can help us explain observed differences in the frequency of monks and nuns in societies with different marriage systems, inheritance rules and post-marital residence rules.

Sibling competition and dispersal drive sex differences in religious celibacy

**Author(s):** Hrnčíř, V; Chira, A Introduction: Alcohol is the most widely used human psychoactive and mind-altering drug. This is partly because its production is very straightforward: any substance that contains sugar can be converted into alcoholic beverage through the natural process of fermentation. Yet, many societies around the world did not know alcohol or forbade its consumption. Our goal is to discover which cultural and ecological factors can explain why some societies produce alcoholic drinks, while others do not.
 Materials & Methods: We coded data for native alcoholic beverages in 186 non-industrial societies (Standard Cross-Cultural Sample). We tested the effect of potentially predictive variables (obtained from D-PLACE) on alcohol production in Bayesian logistic regressions, while accounting for spatial proximity and common ancestry. 
 Results & Discussion: Our results confirm the intuitive assumption that the presence of Islamic religion and the absence of fruit trees and cereals cultivation predict the absence of alcohol. Importantly, we also confirm the strong correlation between the presence of alcoholic beverages and cultural complexity, which has been pointed out before but has not yet been empirically tested. The next step will be to uncover the evolutionary dynamics of this relationship.

Why don't they get drunk? Alcoholic beverages in non-industrial societies

**Author(s):** Tamariz, M.; Papa, A.; Cristea, M.; McGuigan, N. Introduction During our lifetime we typically learn several variants of a given cultural trait, e.g., from family, peers and experts. Social biases affecting which variants are adopted by learners are well-studied. Considerably less is known about influences on the selection of variants for onward transmission by transmitters. This study tests whether a social context congruence effect is in place, i.e., do we tend to transmit to friends behaviours that we learned from friends, to our children behaviours learned from our parents, and to novices behaviours learned from experts? Methods Each of 64 participants learned two cultural variants (methods to solve a puzzle): “E” from an Expert and “P” from a Peer. Then, we

Associative learning and cultural transmission: We teach to novices the variants we learned from experts, and to peers the variants we learned from other peers!

INTRODUCTION: Phylogenetic methods are used for the reconstruction of historical relationships between cultural lineages. These methods, designed for biological evolution, assume traits can only be transferred via inheritance. Little work has been done to determine how the introduction of horizontal transmission, potentially ubiquitous in cultural evolution, affects their accuracy. OBJECTIVE: In this study we tested the robustness of phylogenetic methods when applied to a demographic process with horizontal transmission of traits between groups. APPROACH: We generated synthetic population histories represented as phylogenetic trees. We then simulated variant data on the trees, sampled the terminal nodes and used standard phylogenetic reconstruction methods to construct best fitting trees from the leaf data. We assessed the accuracy of the phylogenetic reconstruction as the distance between the best fitting tree and the ‘true’ tree representation of the demographic history. FINDINGS: Phylogenetic methods are reliable only when the borrowing is constrained to groups with a recent common ancestor. In addition, borrowing can be constrained by either shared ancestry or spatial proximity, leading to significantly divergent inferred trees. CONCLUSION: Preliminary results suggest that the introduction of demographic complexity, including extinction of groups and horizontal transmission events, significantly decreases the accuracy of phylogenetic inference.

Can cultural phylogenies accurately capture spatially explicit demographic scenarios?

**Author(s):** Kasser, S. M.; Blanco-Portillo, J.; Fortunato, L.; Laland, K. N. Objective: Gene-culture coevolution (GCC) theory routinely predicts interactions between cultural and genetic variation that should emerge through empirical analyses, yet evidence for such associations remains sparse. By adapting tools that quantify ecological drivers of population genetic structure ("landscape genomics"), we explore potential cultural drivers of human genetic variation across Oceania to evaluate the extent of GCC.

Methods: We will introduce landscape genomics as a method of quantifying gene-culture coevolution. In a short test case, we use high-density SNP data from Oceanian individuals across 17 island populations from the OGVP (a collaboration between Oxford and Stanford). We then analyse these frequencies using GESTE, a Bayesian procedure to estimate the influence of environmental factors on population genetic structure. For the present analysis, cultural and ecological factors relating to subsistence, kinship practices and island ecology are drawn from relevant cross-cultural datasets.

Results: We will present results on associations between cultural factors and genetic structure.

Discussion: We will discuss the results in the context of recent work on how culture may shape genetic variation beyond classic examples of GCC, and whether landscape genomics represents a useful analogy for quantifying GCC.

Unravelling gene-culture coevolution in the Pacific

**Author(s):** Matthews, Luke J.; Khan, Omair Introduction: Shared understandings of current events are crucial to any functional modern society but common understandings even about factual elements of “what happened” during an event are frequently and hotly contested. Methods: We applied cultural consensus analysis (CCA) and cluster analysis to hundreds of thematically coded journalistic articles from a 2019 air skirmish between India and Pakistan. We applied these methods longitudinally to test alternative hypotheses that either narrative consensus about factual elements increased or decreased over time. Results: Consensus about factual elements of the 2019 air skirmish decreased over a two month period as the narrative diverged into two increasingly thematically distinct clusters. Conclusions: At least regarding the 2019 India-Pakistan air skirmish, journalistic articles decreased in consensus about facts over time. If these results generalize, then media companies might improve shared understandings by repeating articles from closer in time to actual events, as these articles show greater potential for narratives reflecting factual consensus.

Rapid cultural evolution of current event narratives

 As one of the two moderators, I will predominantly lead the theoretical discussion of what are social norms and how could they be identified in animals. I come from the perspective that rather than focusing on some cognitive mechanism that is taken to be necessary for having normativity, investigations into social norms should focus on community level patterns that are supported by social maintenance—positive and negative reinforcement by community members.

Theoretical angles on framing and identifying norms in nonhuman taxa

**Author(s):** Gunst, A; Nylund, E; Marklund A Introduction: Advantageous inequity aversion (i.e., the tendency to respond negatively to unfairness that benefits oneself) usually develops in 6–8-year-olds. However, little is known about the biological and cultural selection of this phenomenon. Materials and Methods: Using data collected from 120 4–8-year-old Finnish children, we tested two evolutionary explanations for the development of advantageous inequity aversion: reciprocal altruism (i.e., benefiting from sharing when the roles are likely reversed in the future) and inclusive fitness (i.e., benefiting from sharing with biological relatives that carry the same alleles). We asked children to distribute five erasers between themselves, a sibling, a friend, and a stranger. That is, an equal distribution was only possible if throwing away one eraser. Results: We found no support for advantageous inequity aversion being shaped by either inclusive fitness or reciprocal altruism. Participants did not show a preference for biological relatives or friends. Rather their behavior reflected a more general tendency for fairness. Discussion: It is possible that adherence to social norms to avoid negative consequences as explains the development of advantageous inequity aversion.

Norms of Fairness: Inclusive Fitness or Reciprocal Altruism Does not Explain Advantageous Inequity Aversion

**Author(s):** Schnell, E; Muthukrishna, M Individuals belong to many different cultural-groups which sometimes have competing interests. For example, one’s company may require frequent flights, which competes with environmental commitments at a larger-scale of cooperation. As such, individuals may be required to choose to cooperate with some groups at the expense of the others. We analytically model cooperation supported by indirect reciprocity with individuals who belong to both a small-scale, local group embedded within a larger-scale, global group. To model cooperation occurring simultaneously at different scales, we extend previous work (Panchanathan & Boyd, 2004) modelling cooperation in a mutual-aid game (MAG) conditional upon cooperation in a previous public goods game (PGG). In our extension, individuals can contribute to either a larger, global PGG or a smaller, local PGG with multipliers adjusted to create competing interests. Individuals then play a MAG amongst their local group. The model shows that by manipulating the multipliers of each PGG, these competing scales can undermine one another. This suggests that indirect reciprocity can maintain cooperation within one cultural-group, while leading to defection among groups with competing interests.

Competing Scales of Indirect Reciprocity

**Author(s):** Lee, H; Schönwiesner, M; Jacoby, N; Park, M

Background: Music is a rich cultural product that is practiced across all known cultures and throughout history, making it an attractive medium to study the transmission and evolution of culture. However, previous research on empirical analysis of music predominantly relied on Western songs, limiting our understanding to WEIRD countries. 
 Method: We introduce a novel dataset called GlobalPOP, which gathers music records from 55 countries since the 1950s by crawling web pages and manually transcribing from books and magazines. The dataset contains over 4 million entries and 254,234 songs with acoustic information, lyrics, and other meta-data gathered from various sources. 
 Results: Using this rich dataset, we provide a quantitative picture on how the general preference of music has converged and diverged across the globe over the last seven decades. Our preliminary findings indicate that most acoustic features reveal a country-specific or regional trend (e.g., danceability, tempo, energy) that can be grouped by the spoken-language and geographical proximity, whereas only a handful of low-level features can be considered as a global trend (e.g., song duration, loudness). 
 Conclusion: We present the first empirical work on the evolution of cross-cultural music preferences by making use of the most comprehensive longitudinal music chart data which will become open-access.

The interaction of learning rules and population turnover can drive cultural evolution

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Sibling competition and dispersal drive sex differences in religious celibacy

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