Denmark

**Author(s):** Nirjhor, M.S.A.; Nakamaru, M.&lt;br&gt;&lt;br&gt;Introduction: Division of labor is based on cooperation among players with various roles on various network structures. It is common in our society but rarely studied from the viewpoint of the evolution of cooperation. We focus on the effects of two possible sanction systems: the defector-sanction system and the 1st role-sanction system, on the evolution of cooperation in the linear division of labor arranged in a unidirectional linear chain. &lt;br&gt;Method: By using the replicator equations of the asymmetric game, we analyze our model; there is a finite number of roles each of which is assigned to one group with cooperators and defectors. A cooperator in an upstream group produces or modifies a product, paying a cost of cooperation, and hands it to a player in a downstream group who obtains a benefit from the product. Costs and benefits are different among groups. If players in all roles cooperate, a final product can be completed. However, if a player in a group chooses defection, the division of labor stops, the final product cannot be completed, and all players in all roles suffer damage. &lt;br&gt;Results &amp; Conclusion: We find that not the benefit but the cost matters to the evolutionary dynamics. We also find that the probability of finding a defector and the initial demography of the groups determine which sanction system promotes cooperation.

Cultural Evolution Society 2022

Effects of sanction systems on the evolution of cooperation in the linear division of labor with finite roles

### 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):** Nirjhor, M.S.A.; Nakamaru, M. Introduction: Division of labor is based on cooperation among players with various roles on various network structures. It is common in our society but rarely studied from the viewpoint of the evolution of cooperation. We focus on the effects of two possible sanction systems: the defector-sanction system and the 1st role-sanction system, on the evolution of cooperation in the linear division of labor arranged in a unidirectional linear chain. Method: By using the replicator equations of the asymmetric game, we analyze our model; there is a finite number of roles each of which is assigned to one group with cooperators and defectors. A cooperator in an upstream group produces or modifies a product, paying a cost of cooperation, and hands it to a player in a downstream group who obtains a benefit from the product. Costs and benefits are different among groups. If players in all roles cooperate, a final product can be completed. However, if a player in a group chooses defection, the division of labor stops, the final product cannot be completed, and all players in all roles suffer damage. Results & Conclusion: We find that not the benefit but the cost matters to the evolutionary dynamics. We also find that the probability of finding a defector and the initial demography of the groups determine which sanction system promotes cooperation.

technical paper

 Swarm Robotics studies collective behaviours of large populations of interacting robots with simple embodied cognition, and is an ideal testbed to study the effect of prosociality on cultural evolution. Building on our previous work, we developed a category game whereby agents collectively discriminate and name regions of an environment that contains food items that are randomly spread around sources. Robots choose their foraging place within “named categories”, thus the category game affects the efficiency of foraging. Agents interact according to two novel features (a) an innate prosociality factor and (b) experience: successful communication between robots reduces their aggression toward each other and increases their chances of interacting again. We observe that when food is spread widely, higher prosociality results in the collection of more items, as collective categories form around the sources. The lexicon created by the robots is a complex cultural artefact that affects foraging efficiency and is subjected to agents’ prosociality. Since foraging efficiency is a factor of survival, our results potentially indicate an evolutionary advantage for prosociality. Higher prosociality would, in turn, enable more complex cultural artefacts to emerge.

Impact of prosociality on culturally evolving foraging habits: a swarm robotics approach

**Author(s):** Campenni, M.; Takahashi, T.; Wada, M. Many human populations on the globe have the law system, obliging individuals to conform to a certain norm, violation of which is usually followed by the punishment from the third-party. Using a model of group competition among distinct subpopulations, we will simulate the co-evolution of the law internalized in a population and the cooperative behavior through prisoner’s dilemma (PD) game with third-party punishment. Unlike the standard PD game, third-party punishment in our model takes place only if the subpopulation in question has the internalized law system. Our model also includes the competition among subpopulations, in which those with higher payoff tend to win. We show that whereas the law and cooperative behavior may evolve for certain parameter sets concerning the payoffs of the PD game, the population will lose the law and be occupied by defectors in majority of the cases.

Co-evolution of cooperative behavior, third-party punishment, and law: Simulation study based on prisoner’s dilemma game

**Author(s):** Walldén, C; Gunst, A; Westerlund, M; Santtila, P; Antfolk, J. We tested the hypothesis that anti-immigration tendencies (e.g., discrimination and negative attitudes towards immigration) can partly be the result of intrasexual competition for mates, especially among heterosexual men. That is, the more an immigrant group is perceived as increasing intrasexual competition, the more anti-immigration tendencies will be displayed by natives. We predicted that native men would display more anti-immigration tendencies than women and that immigrant-specific variables (relationship status, ethnicity-specific prejudice concerning sexual behavior) would predict native men’s anti-immigration tendencies. We presented participants with online vignettes presenting a large group of immigrants of reproductive age and of the participant’s own gender entering into the participant’s home county. We manipulated the relationship status and ethnicity of the immigrant groups. After each vignette, participants reported their anti-immigration tendencies towards the described immigrant group. We also measured participants' self-reported mate access, mate value, and intrasexual competition. We recruited 485 Finnish adults between 25 and 44 years and used available data on their home county’s sex-ratio for their age group as a proxy measure for mate access. As expected, men displayed more anti-immigration tendencies than women and men reported more anti-immigration tendencies against immigrants from the Middle East compared to against immigrants from South-East Asia. Contrary to our hypothesis, intrasexual competition did not predict anti-immigration tendencies among men, but among women. We discuss these findings further.

Intrasexual Competition and Anti-Immigration Tendencies

**Author(s):** Schimmelpfennig, R; Ehret, S; Voigt, S; Efferson, C Theoretical and empirical research suggests that human social learning is both frequency- and payoff-dependent. Less evidence exists about the joint effect of both types of social information. We ran a two-staged incentivised online experiment in Kenya (N=1400). First, participants were ranked based on their performance in a Raven Matrices Task. Second, participants were grouped to make decisions in a sequential task in which participants receive a private signal and can observe the decisions of upstream participants. In a 2x2 factorial design, we manipulated whether high-performing participants would make their decisions early or late in the sequence and whether participants are informed about the ordering or not. We find strong evidence for frequency-dependent social learning across all conditions. However, while frequency- and payoff-dependent cues interact to increase the accuracy of decisions, we don’t find any significant interaction effect on social learning. To understand how learning shapes decisions in complex real-world scenarios, research should further investigate the joint effects of social learning biases for decision-making.

Leveraging social influence for the wisdom of the crowd

**Author(s):** Gunst A, Pedersen I, Antfolk J Introduction: Sibling conflicts are frequent in sibling relationships during childhood and adolescence. However, little is known about the dynamics behind sibling conflicts. Based on the evolutionary theory of parental-offspring conflict, we hypothesized that more conflicts would arise between siblings close (vs. further apart) in age, as they compete for the same type of parental investment. We also studied the alternative hypotheses that more conflicts would arise between siblings close in age as they are more similar and closer to each other. Materials and Methods: We analyzed retrospective survey data from 379 parents in Finland who had at least two children and whose oldest child was a minor. We performed multiple regressions with sibling conflict as the dependent variable, age difference as the dependent variable, and sibling similarity and sibling closeness as mediating variables. Results: We present descriptive results and results from the structural regression model. Discussion: We discuss our findings and the limitations of our study.

Parental investment theory, sibling conflicts and age difference between siblings

**Author(s):** Heckelsmiller, C; Lightner, A. D; Quinlan, M. B. People use folk scientific concepts in ethnomedicine when confronting diseases in humans, other animals, and plants, especially when those organisms are part of a human food system. Yet, little is known about how explanatory models (EMs) of animal and plant diseases adapt when subsistence systems change. Traditionally pastoralists, many Maasai communities in East Africa have intensified agricultural production and interactions with Western scientific paradigms. Using participant observation and interviews with 95 members of a Tanzanian Maasai community, we investigate how participants explain illness events for humans, animals, and plants. We found that people often adopt Western scientific interventions, but keep traditional medical explanations which vary between plant and animal cases. Our findings suggest that EM content for plant and animal disease appears to be differentially constrained by 1) cognitive construals (e.g. a tendency for essentialism, anthropocentrism, teleology); 2) biological coherence; 3) barriers/ attractors to intervention access. We discuss how these factors are important in understanding how folk science evolves and may influence development initiatives.

Ethnomedicine for People, Animals, and Plants; Evolving Explanatory Models in a Changing Subsistence System

**Author(s):** Albuquerque, R; Codogno, B; dos Santos, B; Izar, P In primates, touching is fundamental for the social development of infants. We hypothesized that the frequency of touching the face of other individuals by Sapajus libidinosus infants, assuming an active role within their social network, is correlated to the number of social interactions they establish. We analyzed 41 hours of videos of a wild capuchin group at Piauí, Brazil, recorded using focal animal sampling, from the digital data collection from the Laboratory of Ethology, Development and Social Interactions, corresponding to the 1st, 2nd and 3rd months of life of 6 infants (3 males and 3 females). All social interactions and facial touches involving the infant under analysis were coded. A total of 485 interactions and 45 touches were registered. We conducted a GLMM, considering individual and month as fixed effects and sex as a random variable. We found no correlation between the number of interactions of the infant and the number of touches on the face of other individuals. Future studies should investigate other factors, such as infant temperament, that might explain variation in frequency of touching.

Is the touch of capuchin monkeys infants (Sapajus libidinosus) on other individuals influenced by their popularity?

**Author(s):** Vale, G; McGuigan, N; Whiten, A Humans are distinctive in their propensity for cumulative cultural evolution, yet few studies directly compare human and non-human abilities to solve and socially learn the same increasingly complex tasks. Here we explore chimpanzees’ and children’s solving of an extractive foraging and tool use task, designed to offer opportunities for the emergence of cumulative culture. Groups of 3-4-year-old children and adult chimpanzees were each presented with a large puzzlebox incorporating four increasingly difficult levels of solution. Some required tool use, or building on this, tool modification, to retrieve increasingly preferred rewards. Overall, children, but not chimpanzees, showed some indication of cumulative progress, with group-tested children’s solution complexity surpassing what individuals invented when tested alone. However, after controlling for test time, such that asocial controls and groups received the same exposure to the task, this species difference disappeared. Direct species comparisons further suggest there were no significant differences in the highest task level reached by chimpanzees and children, nor in the number of individuals that solved each task level. Our results suggest that young children may not outperform adult chimpanzees on a cumulatively evolving tool use task.

Testing the scope of cumulative culture in groups of young children and chimpanzees

**Author(s):** Delval, I; Fernández-Bolaños, M; Visalberghi, E; Izar, P; Valentova, JV Among nonhuman primates (NHP), same-sex sexual behavior (SSB) is frequent and appears in several forms, such as courtship, mounting or manual-genital-oral stimulation. Possible functions include practice for heterosexual copulation, tension regulation, reconciliation or bond strengthening. Sexual interactions, though, varies among populations and species. Dual-inheritance perspective can be taken to explore possible interactions between evolved same-sex attractions and specific behaviors that are modified by social learning, occur under specific conditions, and can serve for novel social functions. Capuchin monkeys are known for their rich sexual behavior, with elaborated courtships. While same-sex mounting and genital inspection are common in capuchins’ play, same-sex courtship has been overlooked. Here we describe the first case of two young (one weaning infant and one sub-adult) males of wild-living Sapajus xanthosternos, performing a 15-min courtship. The males performed 16 out of 20 previously described heterosexual behaviors, showing a great overlap with adult courtship. If “practice hypothesis” is correct, this behavior should be widespread among males and females throughout development. Instead, we propose that sex (homosexual and heterosexual) is a powerful and efficient way of communicating social messages, so here it has “strengthening bonds” function. This could extend the prosocial hypothesis for same-sex attraction in humans to NHP.

SOCIALLY MODIFIED MEANING OF SEX: A CASE OF HOMOSEXUAL COURTSHIP IN CAPUCHIN MONKEYS

**Author(s):** Ottoni, E; Coutinho, P; Falótico, T We surveyed tool use by 3 groups of capuchin monkeys in S. das Confusões Nat. Park (Brazil), a savannah population equidistant from two long-term study sites - Faz. Boa Vista, where monkeys are expert nutcrackers, but do not use digging stones nor probes, and S. da Capivara, where all 3 are customary. We employed direct observation, camera traps, indirect observation of tool use sites, and two experiments, one on induced seeds' excavation, the other on probe use, based in a previous comparative study (FBV x PNSC). Nutcracking was observed as expected, but no probing. Stone-aided digging of arthropods and tubers was indirectly registered in the range of one group; one of the other groups (the only one to take part) did not use tools in the digging experiment. In the molasses-probing task, monkeys did not succeed, except by one innovator, but made inept attempts to hit the box with sticks or stones. The results on stone-aided digging are not conclusive but suggest resource-availability causes. The apparent absence of customary probe use, with no clear environmental causes, seems to point to a lower probability of the establishment of a tradition with less cultural niche construction.

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Effects of sanction systems on the evolution of cooperation in the linear division of labor with finite roles

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