**Author(s):** Borg, JM; Buskell, A; Kapitany, R; Powers, ST; Reindl, E; Tennie, C <br><br>The goal of Artificial Life, as articulated by Chris Langton, is “to contribute to theoretical biology by locating life-as-we-know-it within the larger picture of life-as-it-could-be.” The study and pursuit of open-ended evolution in artificial evolutionary systems exemplifies this goal. However, open-ended evolution research is hampered by two fundamental issues; the struggle to replicate open-endedness in an artificial evolutionary system, and the fact that we only have one system (genetic evolution) from which to draw inspiration. Here we argue that cultural evolution should be seen not only as another real-world example of open-ended evolution, but that the unique qualities seen in cultural evolution provide us with a new perspective from which we can assess the fundamental properties of open-ended evolution. Here we highlight the interesting case of human cultural evolution as an open-ended evolutionary system and contextualise cultural evolution under the framework of evolved open-ended evolution. We go on to provide a set of new questions that can be asked once we consider cultural evolution within the framework of open-ended evolution, and introduce new insights that we may be able to gain about evolved open-endedness as a result of asking these questions.

Evolved Open-Endedness in Cultural Evolution: A New Dimension in Open-Ended Evolution Research

**Author(s):** McCauley, B; Roberts, S; Xygalatas, D; Collard, M; Introduction: Permanent body modification (PBM) practices (e.g. tattooing, scarring, piercing) have been a global phenomenon for tens of thousands of years and continue to grow in popularity. However, their potential costs (e.g. infection, infertility, even death) are such that they represent an evolutionary puzzle. Why do people undertake them?
Approach: We reviewed etic explanations for PBM from anthropology, archaeology, psychology, the cognitive science of religion, clinical medicine, and gender studies. We then attempted to interpret each of them in an evolutionary framework.
Results: We identified 31 explanations from over 350 sources. Thirteen of them effectively posit that PBM practices indirectly increase inclusive fitness via their impact on the modified individual’s group, while 10 suggest they directly increase inclusive fitness. The remaining explanations could not be recast in evolutionary terms.
Discussion: Despite the diversity in explanations for PBM practices, evolutionary theory enables most of them to be transformed into a set of competing hypotheses. The next challenge is to generate a systematic cross-cultural dataset on PBM with which to test the hypotheses.

Why do people engage in permanent body modification? A multidisciplinary review

 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):** 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

Domesticated animals and modern humans show a set of behavioral and molecular changes that converge on shared genetic targets. There is evidence that these changes disproportionately target neurotransmission, in particular the glutamatergic signaling system. This has led to proposals that attenuation of glutamatergic signaling may be crucial for the downregulation of the stress response in both modern humans and domesticates and the potentiation of exploratory motor output in our species. Here, we use a deep learning method (ExPecto) to predict gene expression in silico of H. sapiens-specific (relative to the closest extinct human species, Neanderthals and Denisovans) variants of genes involved in glutamatergic signaling. This approach allows us to hone hypotheses about the functional implications of genetic changes in our species' recent evolution, including proposals as to the neurobiological substrates of H. sapiens so called 'self-domestication hypothesis'.

Gene expression under human self-domestication: an in silico exploration of modern human high-frequency variants

In this research I explore the hypothesis that it can be beneficial to the fitness of cultural variants if they channel the energy of the individual who adopts the variant away from biological reproduction and toward the reproduction of the cultural variant. I label this the “inverse correlation hypothesis of cultural maladaptation.” This hypothesis is based on the observation that human biological reproduction is expensive in terms of energy and time. Therefore, cultural traits that minimize reproduction consequently make available resources that an individual could utilize instead to propagate the cultural trait in question. This hypothesis is usually advanced as a plausible explanation of extreme cultural traditions that reduce sexual reproduction to zero, such as celibacy. My first task is to discuss the implications of this hypothesis and to argue that, although it has merits, it has only been given a superficial scientific treatment in the literature, which is unfortunate. The reason for this, I argue, might be due to a vague theoretical distinction between, on the one hand, cultural maladaptive traits that nullify biological fitness and, on the other, selectively neutral or non-adaptive cultural traits that do not affect fitness values. My second task is to articulate an adequate theoretical framework that makes the inverse correlation hypothesis a scientifically respectable explanation of cultural maladaptation. I discuss some theoretical and empirical challenges that this hypothesis faces, but that they are not fatal as they are well-trodden by evolutionary biologists and philosophers.

The inverse correlation hypothesis of cultural maladaptation.

There is a long-standing debate considering the possibility of sympatric speciation, the origin of multiple species from one, without geographic isolation. Although the central position of the geographical aspect of speciation had suffered significant demise recently, spatial isolation is still believed to play a pivotal role in divergent evolution by limiting gene flow between adjacent populations. Here we present a novel model combining assortative mating and multidimensional inheritance. The continuous inheritance between interacting agents can approximate additive genetic (Galton-Pearson model) or social (Parental Variability-Dependent Inheritance) transmission, or a combination of the two. We demonstrate that in a model where variance of inputs is proportional to the variance of outputs, the assortment alone can lead to the formation of distinct, cohesive clusters of individuals with low within-group and large between-group variability even in the absence of disruptive natural or cultural selection.
Subcultures can, therefore, emerge even without the preferential imitation of self-similar individuals. All it takes is the negative relationship between the probability of interaction and the distance in the culture-space.
The model explains the constant and frequent sympatric emergence of subcultures and varieties with limited gene flow that can only later diverge ecologically and possibly speciate. This model might be particularly relevant for taxa with a high capacity for cultural evolution, such as cetaceans, songbirds, and hominins, known for their increased potential to undergo adaptive ecological radiation.

Assortative interaction leads to the emergence of subcultures even without selective imitation

In this paper I depart from the traditional Price-equation formulation of multilevel selection and introduce a new theoretical approach of a multi-level selection process where phases of intra-group interactions alternate with phases of interaction among groups. I assume that a given genetic allele or cultural trait is maladaptive for individuals bearing it but increases the fitness of others in the same group (like altruism), but groups with a higher fraction of bearers of the trait have an advantage in the inter-group interaction phases and reproduce faster. Two main results are obtained that had remained somehow hidden in the traditional model: (1) For group selection to overcome the opposing effect of individual selection the key factor is the amount of “positive” variation in groups’ reproduction, not the strength of group selection per se. (2) Multilevel selection is vulnerable to invasion by mutants that inhibit the phenotypic effect of the allele or cultural trait in the intra-group phases but allow its expression in the between-group phases, in a similar process that make green beards genes unlikely to evolve. By discriminating its phenotypic effects depending on appropriate cues in both environments, the mutated trait restores the selfish behavior when it serves the individual but maintains the altruistic effect when it serves both the group and the individual. This can be interpreted as breaking the “public good” link of the original allele or trait regarding its positive effect in the inter-group competition in relation to its detrimental effects in the intra-group competition phases.

Selection pressures against multilevel selection

The evolution and function of imitation in animal learning has always been associated with its crucial role in cultural transmission and evolution. Can imitation evolve in the absence of cultural transmission? We investigate a model of a semelparous organism with discrete, nonoverlapping generations in which the sole transmission of information between generations is genetic. We suppose that an organism can modify its phenotype in response to the phenotypes it observes in its cohort of conspecifics. We find that during a period of directional selection towards a phenotypic optimum, natural selection favors modifiers which cause an organism to bias its plastic phenotype in the direction \emph{opposite} to the mean phenotype of the population. As the population approaches the phenotypic optimum and shifts into stabilizing selection, selection on the modifier reverses and favors strong imitation of the population mean. Imitation can become so strong that ``genotype-phenotype disengagement'' occurs (Gonzalez, Watson, and Bullock 2017), and for multivariate phenotypes evolution can cycle between genotype disengagement and re-engagement. While in some cases the evolution of imitation and anti-imitation increase the mean fitness of the population, cycles of genotype disengagement and re-engagement can make the mean fitness nonmonotonic in time.

The Evolution of Imitation Without Cultural Transmission

The existence of sharp stone tools is sometimes used as evidence for early cultural evolution in hominins. Yet, it is an open question whether these tools required cultural transmission of their underlying know-how. The main, but previously untested, alternative is that the know-how underlying these tools was the outcome of biologically evolved abilities (adaptations/exaptations). Here we tested – for the first time – whether non-human great apes may be spontaneously able to innovate the neccessary know-how to produce and use sharp stone tools. This required us to test apes in the absence of human enculturation and in the absence of human know-how demonstrations. Eleven chimpanzees were tested in this way. All proved motivated to engage in the tasks given, but not a single chimpanzee spontaneously made or used sharp stone tools. Our results stand in sharp contrast to the positive outcomes of earlier ape sharp stone tool experiments. However, all three apes that were previously tested (one orangutan and two bonobos) had received both human enculturation and human know-how demonstrations prior to their test (even active moulding of actions was sometimes applied). Human enculturation and/or human know-how demonstrations may thus be necessary before apes acquire sharp stone tool abilities. This would suggests that sharp stone tool manufacture and use has evolved – culturally and/or biologically – in the hominin lineage after the split between Homo and Pan.

Unenculturated chimpanzees fail to produce and use sharp stone tools in the absence of know-how demonstrations

Presented is a force-based alternative to the transmission-based model of cultural evolution. The premise is that the majority of cultural evolution is Darwinian selection that occurs in the mind. The selection is driven by internal and external stressors (forces) leading to creative tension. Transmission is viewed as a source of variation and stressors, not heredity. 

One barrier to a force-view of cultural evolution is that biological evolution has not served as a helpful exemplar. The forces in natural selection are traditionally misidentified (or ignored). Here the forces of natural selection are environmental stressors acting on individuals, not natural selection itself. With this understanding, I will present the cultural evolutionary analogs to the dimensions of biological evolution including phenotype, variation, heredity, driving forces, fitness, and generations.

The impetus for this view of cultural evolution comes from the study of strategy and innovation developed in part during my 25 years at E.I. DuPont, the multinational chemical and materials company. In addition to my scientific role there, I held positions in business, venture management and strategic planning. 

I will show how the force-based model aligns with an adaptive view of strategy theory and practice. Understanding how stressors act on ideas, processes, and technologies is key to enabling innovation in all endeavors.

A Force-based Model of Cultural Evolution with Application to Business Strategy

Why do people choose to follow a demanding moral authority even in situations in which a less demanding alternative exists? Can social imitation alone sustain meaningful moral equilibrium? Why is moral authority concentrated in the sense that multiple individuals follow the same authority? What factors underpin and limit the power of moral authorities, and why do authorities lose influence? This paper addresses these questions by developing a formal choice-theoretic model of moral authorities, moral standards, and moral behavior. We show that sustaining meaningful moral behavior is only possible if some actors choose to provide, and others choose to follow, a person providing moral guidance through their behavior. Our theory builds on literature in cultural evolution, biology, and psychology on how human pro-sociality has become an adaptive trait. In an extension of our model, we analyze the role of the state. We show that only two types of states can maximize social welfare: morally liberal states with low redistribution, or, morally conservative states with high redistribution.

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Evolved Open-Endedness in Cultural Evolution: A New Dimension in Open-Ended Evolution Research

Why do people engage in permanent body modification? A multidisciplinary review

Cultural evolution of cooperation with non-vertical transmission

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

Gene expression under human self-domestication: an in silico exploration of modern human high-frequency variants

The inverse correlation hypothesis of cultural maladaptation.

Assortative interaction leads to the emergence of subcultures even without selective imitation

Selection pressures against multilevel selection

The Evolution of Imitation Without Cultural Transmission

Unenculturated chimpanzees fail to produce and use sharp stone tools in the absence of know-how demonstrations

A Force-based Model of Cultural Evolution with Application to Business Strategy

A Theory of Moral Authority: Moral Choices Under Moral Network Externality

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