Denmark

**Author(s):** Itao K; Kaneko K &lt;br&gt;&lt;br&gt;Anthropologists have observed gift relationships that establish social relations as well as the transference of goods in many human societies. The totality of social relations constitutes the network. Social scientists have analyzed different types of social organizations with characteristic network. However, the factors and mechanisms that cause the transition between these types are hardly explained. Here, we focus on the gift as the driving force for such change. We build the model by idealizing gift interactions and simulate the consequent social change due to long-term massive interactions. Through simulation, we demonstrate that as the frequency of the gift increases, the network structures are less clustered and more hierarchically organized. Also, the economic and social disparities successively emerge. These transition corresponds to the change from bands to tribes and to chiefdoms. Following this, statistical analysis using the Standard Cross-Cultural Sample, a global ethnographic database, empirically verifies the theoretical results on the emergence of disparities and hierarchical organizations due to the increase in the gift.

Cultural Evolution Society 2022

Transition of Social Organizations Driven by Gift Relationship

agent-based modeling; cultural anthropology; social organization; gift; history

### 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

Please click on the button bellow if you want to watch the videos

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):** Itao K; Kaneko K Anthropologists have observed gift relationships that establish social relations as well as the transference of goods in many human societies. The totality of social relations constitutes the network. Social scientists have analyzed different types of social organizations with characteristic network. However, the factors and mechanisms that cause the transition between these types are hardly explained. Here, we focus on the gift as the driving force for such change. We build the model by idealizing gift interactions and simulate the consequent social change due to long-term massive interactions. Through simulation, we demonstrate that as the frequency of the gift increases, the network structures are less clustered and more hierarchically organized. Also, the economic and social disparities successively emerge. These transition corresponds to the change from bands to tribes and to chiefdoms. Following this, statistical analysis using the Standard Cross-Cultural Sample, a global ethnographic database, empirically verifies the theoretical results on the emergence of disparities and hierarchical organizations due to the increase in the gift.

technical paper

 When precise imitation of an average cultural trait (e.g. from multiple prestigious individuals) is the goal, the error-prone approximation of the average is the unavoidable outcome. The Galton-Pearson (GP) inheritance model, where a constant standard deviation characterises the error, is currently the mainstream in cultural evolution. We aimed to test whether this assumption is justified when individuals directly observe and imitate multiple 'phenotypes'. Each of 200 participants received 10 sheets of paper containing a randomly positioned pair of black dots and was instructed to mark an intermediate point between the dots as precisely as possible. Imitation error was directly proportional to the difference between demonstrator positions. The model, where the standard deviation of 'cultural offspring' is proportional to the standard deviation of 'cultural parents', explained 88% more variance than the GP model. Previous simulation work has shown that different inheritance models lead to different macroevolutionary patterns. Therefore, this result has profound implications for evolutionary trajectories if the adaptation is due to cultural and not biological inheritance.

Making a point: The imitation error is proportional to the difference between the demonstrators

 Introduction. The evolution of cooperation is a long-standing problem in evolutionary theory. However, cooperation is usually assumed to be genetically transmitted, despite evidence the prosocial behaviors are socially learned in humans as well as non-human animals (e.g., killer whales).

Cultural evolution of cooperation with non-vertical transmission

**Author(s):** Ammar, M; Fogarty, L; Kandler, A The ability to remember many cultural traits, and the context in which it is best to use them, is a clear feature of human cognition. However, this is rarely considered in models of the evolution of social learning. Without memory such models found that the benefit of innovation increases with environmental variability and social learning is most useful in stable environments. In our agent-based model, we investigate the interaction between memory and social learning and its implication for adaptation. With memory, agents can store information about traits they have learned and recall this later. The environment can change between time steps and agents use stored information to assess their traits in the current environment. Here ‘forgetting’ is a probabilistic process where rarely used traits are more easily forgotten than those frequently used. We consider how the rates of forgetting and social learning co-evolve. Large memories limit the need for innovation in rapidly changing environments by increasing the probability that individuals have adaptive information after an environmental change. This is driven by the presence of reservoirs of unexpressed persistent cultural variation. We explore the structure of ‘ideal’ cultural repertoires, balancing the probability of using the wrong cultural trait with retaining beneficial traits. This balance in turn affects the amount of social learning in stable environments. This approach to memory in cultural evolution changes our understanding of the evolution of social learning in fluctuating environments.

Memory and Social Learning

**Author(s):** Nilo M. Recalde, Ben C. Sheldon Population processes like dispersal, immigration and turnover play an essential role in evolution: they determine which individuals meet and reproduce and, as a result, shape the distribution of genetic diversity over space and time. By influencing when and which individuals interact, these processes also have the potential to affect traits that are culturally, rather than genetically, inherited, such as bird song. 


Teasing apart the relative contributions of population processes to the evolution of cultural traits is difficult, however, because it requires dense trait sampling and detailed individual life-history data—both notoriously hard to acquire in wild populations. To this end, we have built a multi-generational dataset containing the full song repertoires of hundreds of individuals in a population of great tits (Parus major) monitored extensively at Wytham Woods, UK. 


While simple at first impression, great tit songs are surprisingly diverse, and they give rise to a population-level cultural landscape that shifts continuously. Here, we take advantage of our long-term individual data and, using newly developed computational tools for studying large bird song datasets, show how demographic factors contribute to shaping local song diversity and complexity over multiple spatial and temporal scales.

Demography and cultural evolution in the wild: the landscape of diversity in bird song

**Author(s):** Tyndel, S; Carlos, J; Aplin, LM; McElreath, MB Language is a hallmark of human evolution, and probably one of the main catalysts for cumulative cultural evolution in our species. While it is hard to study early language evolution directly, animal models can be useful to understand evolutionary drivers of communication. Parrots are similar to primates in social and cognitive complexity, but unlike primates, are known for their life-long flexible vocal learning across multiple contexts. Parrots use social contact calls that enabling other individuals to stay in touch even in dense vegetation. Multiple studies have found group or location specific dialects in contact calls, suggesting social learning. It has also been suggested that these calls are individually distinct and enable individual recognition. However, it is unclear whether, and how, social calls can be used for both functions within the same species. Here, we studied variation in monk parakeet (Myiopsitta monachus) calls at three levels using multilevel Bayesian models: individual, colony and population. We show that they have distinct dialects across cities, evidencing social learning. We further show that individuals have a distinctively recognisable ‘voice print’ across call types. This is the first evidence of such a voice print in a vocal learner outside of humans, and demonstrates how both dialects and individual recognition is possible in a flexible vocal learner.

Monk parakeets exhibit individual vocal signatures and population-level dialects in their vocalisations

**Author(s):** Lu, Y. T.; Colleran, H. Fertility decline may involve quantity-quality trade-offs among children, and many studies assume this is adaptive via costs and benefits of wealth accumulation and transmission. Few models have explored these hypotheses over the long term. Here we ask: does wealth-stratification generate fertility declines when the marginal costs to reproduction (interpretable as cultural or economic perceptions) differ by class? 

We develop an ABM whereby agents inherit both parental wealth and a resource allocation strategy. They allocate wealth between fertility and inheritance in 1) a setting with density-dependent death and 2) a setting where wealth classes experience differential costs to reproduction. Descendant wealth is determined by the combination of inheritance and a random income contribution from the environment.

Preliminary results show that parents investing more in fertility than bequests leave more descendants over time. This dynamic converges faster in the second setting. Greater stratification also leads upper-class parents to have fewer children than the middle class, consistent with arguments that the wealthiest classes lead the demographic transitions.

We suggest that wealth stratification may be crucial in explaining historical fertility.

The coevolution of human fertility and wealth stratification

A preference for having a particular number of children is a cultural trait expected to influence the fertility outcome of a woman. However, fertility preferences often do not match with the realised fertility of a woman. This pattern is probably because not much is known on how fertility desires actually vary, only that they are highly context-dependant. Furthermore, there is no clear understanding on how the social context shapes the fertility preferences of a woman. Here, we study how the social fertility context at the family, peer, and community level shapes the ideal family size of women from rural Poland. 
We build a Bayesian cross-classified multi-level model to account for the structure in the clustering at the family, peer, and community levels, and analyse how the average number of children ever born among clusters may shape the ideal number of children of Polish women (n=1,995). 
The results will show to what extent the ideal number of children is clustered at the family, peer, and community levels. Specifically, the results will show how the mean fertility of the different clusters predicts the direction of the fertility preferences of a woman. 
Knowing how the variability of fertility preferences is decomposed among the family, peers, and community levels can contribute to understand how the social context shapes culturally transmitted traits related to fertility.

How family, peers, and community matter in the differences of fertility preferences among women from rural Poland

**Author(s):** Kaaronen, R.O.; Manninen, M.A.; Eronen, J.T. Introduction
Measurement systems are key drivers of cultural evolution. Early standardized measurement systems evolved from body-based units of measure, such as the cubit. Previous research has implied that ‘advanced’ standardized units replaced ‘primitive’ body-based units. We argue that this is not the whole story, and that body-based measurement persisted up until recent times to serve specific cultural-technological functions. 
Materials/Methods
We collect ethnographic data from eHRAF and a literature review, documenting the use of body-based units. We develop a typology of body-based units and classify the cultural domains in which they are used. To study whether standardized systems replaced body-based systems, we collect data on the earliest evidence of standardization in each region.
 Results
We find body-based units in 186 cultures around the world. We find that body-based units persisted centuries after the emergence of standardization. We describe how body-based units afforded the elaborate ergonomic design of various key technologies (e.g., kayaks, bows) which facilitated human adaptation. 
Discussion
We discuss advantages of body-based units, including ergonomics, ease of use and availability. We discuss how standardization emerged rather as a tool for statecraft than for practical crafts, and how rules of thumb fell out of favor during industrial mass production.

Body-based units of measure in cultural evolution

 The Database of Religious History (DRH) consists of a series of polls, including mainly quantitative questions. There are many challenges for the analysis of DRH data—How to select a sample of religious groups? How to handle missing data? How to handle disagreement between experts? In this presentation I will address how these challenges have been managed in recent analysis. In particular I will focus on the challenge of defining a useful data set from the DRH sample to answer specific questions.

Challenges for Quantitative Analyses of History: Examples from the Database of Religious History

 Religious beliefs show profound cultural and historical diversity, and this diversity can yield insights into the ecological and cognitive foundations of religion. However, most studies of religious belief use participants from large industrialized nations who belong to major world religions. Here we describe an initiative to extract qualitative descriptions and quantitative codes for two major kinds of religious beliefs—characteristics of gods and spirits, and characteristics of supernatural explanations—using the ethnographic record. Our data cover 115 societies, 850 different supernatural agents, and thousands of different supernatural explanations. We also feature rich meta-data describing the ethnographic texts (e.g., source, field date) and societies. In this presentation, we will share early empirical insights from this database and a timeline for making the qualitative and quantitative data publicly accessible.

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Transition of Social Organizations Driven by Gift Relationship

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