Denmark

**Author(s):** Gunst A, Pedersen I, Antfolk J &lt;br&gt;&lt;br&gt;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. &lt;br&gt;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. &lt;br&gt;Results: We present descriptive results and results from the structural regression model. &lt;br&gt;Discussion: We discuss our findings and the limitations of our study.

Cultural Evolution Society 2022

Parental investment theory, sibling conflicts and age difference between siblings

parental investment

sibling conflict

evolutionary psychology

Metabolic rate is closely related to body size (body mass), but when mass increases, metabolic rate usually increases less. This allometric scaling relationship between metabolic rate and body mass is fundamental to biology and widely applied, but also one of the most debated concepts in integrative and comparative physiology, ecology, and evolutionary biology.

Several theories and hypotheses have been put forward to explain why and how metabolic rate scales with body mass, and why there appears to be variation in how steep this scaling relationship is among different taxa and physiological or ecological conditions (e.g. 'surface area', 'cell size', 'fractal distribution network', ‘dynamic energy budget’, and ‘metabolic-level boundaries’ theories or hypotheses). However, the lack of consensus on these important topics is a major barrier to our understanding of the pace at which organisms of different sizes and species expend energy and need to consume resources such as food and oxygen from the environment. It also limits our ability to predict how metabolic rate and body size (co)evolves, and how climate change affects metabolic demands and body sizes, as metabolic scaling exponents are used to model how these key organismal traits are affected by changing temperature and oxygen levels. The importance of metabolic scaling is clear, yet it remains one of the most controversial concepts in biology.

The overall aim of this satellite meeting is to bring together researchers working with metabolic scaling, to: (1) bring the field up to speed on state-of-the-art knowledge and research on metabolic scaling; (2) help understand how the vastly different views and opinions on metabolic scaling can persist despite more than a century of research (e.g. scaling in proportion to surface area or not, universal ¾-power scaling or not, governed by ecological vs. physical or geometric factors); and (3) identify and help streamline specific areas of research on metabolic scaling that will be particularly important for our further understanding of why and how metabolic rate scales with body size.

The meeting is being organised as part of the Animal Section of the SEB and will therefore have a focus on metabolic scaling of animals, but work on other organisms is welcome where this can provide insight into metabolic scaling in general.

Why and how does metabolic rate scale with body size?

The overall aim of this satellite meeting is to bring together researchers working with metabolic scaling, to: bring the field up to speed on state-of-the-art knowledge and research on metabolic scaling; help understand how the vastly different views and opinions on metabolic scaling can persist despite more than a century of research (e.g. scaling in proportion to surface area or not, universal ¾-power scaling or not, governed by ecological vs. physical or geometric factors); and identify and help streamline specific areas of research on metabolic scaling that will be particularly important for our further understanding of why and how metabolic rate scales with body size.

**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.

technical paper

### 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.

 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):** 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.

Comparing the toolkits of three savannah populations of bearded capuchin monkeys (Sapajus libidinosus): environmental and traditional factors.

Humans use a wide variety of representational patterns to express numbers. Some of these representations also straddle different modalities, and sign languages (SLs) are a prime example: Their users produce and receive signals in visuospatial space but adopt tools and strategies linked to the oral/auditory modality; and in SLs numerals resemble notational systems. At the same time, systems may possess rare features that are neither attested in SLs used by neighboring communities nor related to the surrounding spoken languages. Such features include, for instance, how compound numbers are structured or whether number representation is quantitative or symbolic, and whether the form involves hand movements or repetitions. Because of this variety in structure and form, numerals in SLs challenge cross-modality feature analysis. In this talk, I will show how a distributed cognition approach can be made fruitful for their analysis. This approach recognizes that numerical cognition operates on information that is distributed across internal and external representations, and that the way in which numbers are externally represented shapes cognitive behaviors (representational effects).


A distributed approach to numerals in sign languages

In groups of the Evangelical tradition, public conversion testimonies are essential when considering a neophyte for membership. Interestingly, in these groups, every member must undergo conversion experience and display their converted nature – actual converts and those brought up in the tradition. In their public conversion testimonies, members signal their loyalty to the group and try to convince others about their commitment and trustworthiness. Contrary to the group's theology that both groups of neophytes are equal, my previous study found significant differences in public conversion testimonies between the individuals who have been part of the group since childhood and strangers in the effort to persuade others operationalized as the length of testimony and amount of negative self-depiction. Except for this difference in public conversion testimonies, their function remains unknown, and we are at the beginning of its understanding. Based on these findings, I'd like to present a research design to study changes in commitment for both groups and if high-conversion performers are treated more for their commitment than low-conversion performers.

Public conversion testimonies and group commitment

We investigate how aggression towards enemy out-group spreads among in-groups during intergroup conflicts. Focusing on the role of learning biases, we tested whether prestige and credibility enhancing displays of in-group leaders motivate other in-groups to participate in intergroup aggression. Using a minimal group paradigm and an intergroup prisoner’s dilemma with maximized differences on a Czech sample, our results show that the transmission of intergroup aggression is promoted by credibility enhancing displays and by the prestige of group leaders, not their dominance. Furthermore, taking advantage of the naturally occurring event, the storming of the US Capitol, we studied whether group affiliation influences how Americans perceive the aggressive behavior of the shooting officer and shot A. E. Babbitt. Our findings suggest that the group affiliation and the support for the storming predict perceived prestige and dominance diversely for both actors. We conclude that given the context of an intergroup conflict, leaders can increase participation in aggressive behaviors towards out-groups by prestigious motivation, sidestepping the coercive pathway of dominance.

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