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Primate brains differ in size and architecture. Hypotheses to explain this variation are numerous and many tests have been carried out. However, after body size has been accounted for there is little left to explain. The proposed explanatory variables for the residual variation are many and covary, both with each other and with body size. Further, the data sets used in analyses have been small, especially in light of the many proposed predictors. Here we report the complete list of models that results from exhaustively combining six commonly used predictors of brain and neocortex size. This provides an overview of how the output from standard statistical analyses changes when the inclusion of different predictors is altered. By using both the most commonly tested brain data set and the inclusion of new data we show that the choice of included variables fundamentally changes the conclusions as to what drives primate brain evolution. Our analyses thus reveal why studies have had troubles replicating earlier results and instead have come to such different conclusions. Although our results are somewhat disheartening, they highlight the importance of scientific rigor when trying to answer difficult questions. It is our position that there is currently no empirical justification to highlight any particular hypotheses, of those adaptive hypotheses we have examined here, as the main determinant of primate brain evolution. [ABSTRACT FROM AUTHOR]

Objectives: This article presents a new method inspired by evolutionary biology for analyzing longer sequences of requisites for the emergence of particular outcome variables across numerous combinations of ordinal variables in social science analysis. Methods: The approach is a sorting algorithm through repeated pairwise investigations of states in a set of variables and identifying what states in the variables occur before states in all other variables. We illustrate the proposed method by analyzing a set of variables from version 7.1 of the V‐Dem data set (Coppedge et al. 2017. Varieties of Democracy (V‐Dem) Project; Pemstein et al. 2017. University of Gothenburg, Varieties of Democracy Institute: Working Paper No. 21). With a large set of indicators measured over many years, the method makes it possible to identify and compare long, complex sequences across many variables. Results: This affords an opportunity, for example, to disentangle the sequential requisites of failing and successful sequences in democratization, or if requisites are different during different time periods. Conclusions: For policy purposes, this is instrumental: Which components of democracy occur earlier and which later? Which components of democracy are therefore the ideal targets for democracy promotion at different stages? [ABSTRACT FROM AUTHOR]

In this paper, I draw on knowledge from several disciplines to explicate the potential evolutionary significance of health effects of religiosity. I present three main observations. First, traditional methods of religious healers seldom rely on active remedies, but instead focus on lifestyle changes or spiritual healing practices that best can be described as placebo methods. Second, actual health effects of religiosity are thus mainly traceable to effects from a regulated lifestyle, social support networks, or placebo effects. Third, there are clear parallels between religious healing practices and currently identified methods that induce placebo effects. Physiological mechanisms identified to lie behind placebo effects activate the body's own coping strategies and healing responses. In combination, lifestyle, social support networks, and placebo effects thus produce both actual and perceived health effects of religiosity. This may have played an important role in the evolution and diffusion of religion through two main pathways. First, any real positive health effects of religiosity would have provided a direct biological advantage. Second, any perceived health effects, both positive and negative, would further have provided a unique selling point for 'religiosity' per se. Actual and perceived health effects of religiosity may therefore have played an underestimated role during the evolution of religiosity through both biological and cultural pathways. [ABSTRACT FROM AUTHOR]

What determines countries' successful transition to democracy? This article explores the impact of granting civil rights in authoritarian regimes and especially the gendered aspect of this process. It argues that both men's and women's liberal rights are essential conditions for democratisation to take place: providing both women and men rights reduces an inequality that affects half of the population, thus increasing the costs of repression and enabling the formation of women's organising - historically important to spark protests in initial phases of democratisation. This argument is tested empirically using data that cover 173 countries over the years 1900-2012 and contain more nuanced measures than commonly used. Through novel sequence analysis methods, the results suggest that in order to gain electoral democracy a country first needs to furnish civil liberties to both women and men. [ABSTRACT FROM AUTHOR]

We have carried out an empirical study of long-term change in European cookery to test if the development of this cultural phenomenon matches a general hypothesis about cultural evolution: that human cultural change is characterized by cumulativity. Data from seven cookery books, evenly spaced across time, the oldest one written in medieval times (~1200) and the most recent one dating from late modernity (1999), were compared. Ten recipes from each of three categories ('poultry recipes', 'fish recipes,' and 'meat recipes') were arbitrarily selected from each cookery book by selecting the first ten recipes in each category, and the numbers (per recipe) of steps, separate partial processes, methods, ingredients, semi-manufactured ingredients, compound semi-manufactured ingredients (defined as semi-manufactured ingredients containing no less than two raw products), and self-made semi-manufactured ingredients were counted. Regression analyses were used to quantitatively compare the cookery from different ages. We found a significant increase in the numbers (per recipe) of steps, separate partial processes, methods, ingredients, and semi-manufactured ingredients. These significant increases enabled us to identify the development of cookery as an example of the general trend of cumulativity in long-term cultural evolution. The number of self- made semi-manufactured ingredients per recipe, however, tended to decrease over time, which may reflect the cumulative characteristics of cultural evolution at the level of society, considering the accumulation of knowledge that is required to industrialize food production. [ABSTRACT FROM AUTHOR]

Transitions to democracy are most often considered the outcome of historical modernization processes. Socio-economic changes, such as increases in per capita GNP, education levels, urbanization and communication, have traditionally been found to be correlates or 'requisites' of democratic reform. However, transition times and the number of reform steps have not been studied comprehensively. Here we show that historically, transitions to democracy have mainly occurred through rapid leaps rather than slow and incremental transition steps, with a median time from autocracy to democracy of 2.4 years, and overnight in the reverse direction. Our results show that autocracy and democracy have acted as peaks in an evolutionary landscape of possible modes of institutional arrangements. Only scarcely have there been slow incremental transitions. We discuss our results in relation to the application of phylogenetic comparative methods in cultural evolution and point out that the evolving unit in this system is the institutional arrangement, not the individual country which is instead better regarded as the 'host' for the political system. [ABSTRACT FROM AUTHOR]

Background: There exists substantial variation in human stature and sexual stature dimorphism that has been attributed to both genetic and environmental variables. A few studies have previously investigated possible relationships between latitude and stature, building on the idea that variation in climate can influence body size (Bergmann's rule). This change in body size can in turn have influenced sexual stature dimorphism (in accordance with Rensch's rule). Aim: The present study investigated whether latitude is associated with variation in human mean stature and sexual stature dimorphism. Subjects and methods: Phylogenetic and non-phylogenetic analyses were conducted on a cross-cultural sample of 124 human populations. Results: The results indicate that both male and female mean stature increase with increasing distance from the equator. While sexual stature dimorphism also was positively related to latitude in the non-phylogenetic test, this relationship disappeared when using a phylogenetic comparative method. Evidence was also found for curved relationships between latitude and both male and female stature, as well as stature dimorphism, all indicating a maximum at around 40° from the equator. Conclusions: The results of the present study indicate that both male and female stature are weakly associated with latitude. It is possible that these relationships are evolved responses to variation in climate. No unequivocal conclusion could be drawn regarding a possible relationship between latitude and sexual stature dimorphism. [ABSTRACT FROM AUTHOR]

Aim Comparative studies have revealed strong links between ecological factors and the number of parasite species harboured by different hosts, but studies of different taxonomic host groups have produced inconsistent results. As a step towards understanding the general patterns of parasite species richness, we present results from a new comprehensive data base of over 7000 host–parasite combinations representing 146 species of carnivores (Mammalia: Carnivora) and 980 species of parasites. Methods We used both phylogenetic and non-phylogenetic comparative methods while controlling for unequal sampling effort within a multivariate framework to ascertain the main determinants of parasite species richness in carnivores. Results We found that body mass, population density, geographical range size and distance from the equator are correlated with overall parasite species richness in fissiped carnivores. When parasites are classified by transmission mode, body mass and home range area are the main determinants of the richness of parasites spread by close contact between hosts, and population density, geographical range size and distance from the equator account for the diversity of parasites that are not dependent on close contact. For generalist parasites, population density, geographical range size and latitude are the primary predictors of parasite species richness. We found no significant ecological correlates for the richness of specialist or vector-borne parasites. Main conclusions Although we found that parasite species richness increases instead of decreases with distance from the equator, other comparative patterns in carnivores support previous findings in primates, suggesting that similar ecological factors operate in both these independent evolutionary lineages. [ABSTRACT FROM AUTHOR]

Background: Social and competitive demands often differ between the sexes in mammals. These differing demands should be expected to produce variation in the relative sizes of various brain structures. Sexual selection on males can be predicted to influence brain components handling sensory-motor skills that are important for physical competition or neural pathways involving aggression. Conversely, because female fitness is more closely linked to ecological factors and social interactions that enable better acquisition of resources, social selection on females should select for brain components important for navigating social networks. Sexual and social selection acting on one sex could produce sexual dimorphism in brain structures, which would result in larger species averages for those same brain structures. Alternatively, sex-specific selection pressures could produce correlated effects in the other sex, resulting in larger brain structures for both males and females of a species. Data are presently unavailable for the sex-specific sizes of brain structures for anthropoid primates, but under either scenario, the effects of sexual and social selection should leave a detectable signal in average sizes of brain structures for different species. Results: The degree of male intra-sexual selection was positively correlated with several structures involved in autonomic functions and sensory-motor skills, and in pathways relating to aggression and aggression control. The degree of male intra-sexual selection was not correlated with relative neocortex size, which instead was significantly positively correlated with female social group size, but negatively correlated with male group size. Conclusion: Sexual selection on males and social selection on females have exerted different effects on primate brain architecture. Species with a higher degree of male intra-sexual selection carry a neural signature of an evolutionary history centered on physical conflicts, but no traces of increased demands on sociocognitive tasks. Conversely, female sociality is indicated to have driven the evolution of socio-cognitive skills. Primate brain architecture is therefore likely to be a product of ecological and species-specific social factors as well as different sex-specific selection pressures. Our results also highlight the need for acquisition and analysis of sex-specific brain components in mammals. [ABSTRACT FROM AUTHOR]

Phylogenetic comparative methods were used to analyze the consequences of sexual selection on canine size and canine size dimorphism in primates. Our analyses of previously published body mass and canine size data revealed that the degree of sexual selection is correlated with canine size dimorphism, as well as with canine size in both sexes, in haplorhine but not in strep-sirrhine primates. Consistent with these results, male and female canine size was found to be highly correlated in all primates. Since canine dimorphism and canine size in both sexes in haplorhines were found to be not only related to mating system but also to body size and body size dimorphism (characters which are also subject to or the result of sexual selection), it was not apparent whether the degree of canine dimorphism is the result of sexual selection on canine size itself, or whether canine dimorphism is instead a consequence of selection on body size, or vice versa. To distinguish among these possibilities, we conducted matched-pairs analyses on canine size after correcting for the effects of body size. These tests revealed significant effects of sexual selection on relative canine size, indicating that canine size is more important in haplorhine male-male competition than body size. Further analyses showed, however, that it was not possible to detect any evolutionary lag between canine size and body size, or between canine size dimorphism and body size dimorphism. Additional support for the notion of special selection on canine size consisted of allometric relationships in haplorhines between canine size and canine size dimorphism in males, as well as between canine size dimorphism and body size dimorphism. In conclusion, these analyses revealed that the effects of sexual selection on canine size are stronger than those on body size, perhaps indicating that canines are more important than body size in haplorhine male-male competition. [ABSTRACT FROM AUTHOR]

In many animal groups, sexual size dimorphism tends to be more pronounced in species with large body size. Similarly, in a previous cross-cultural analysis, male and female stature in humans were shown to be positively allometrically related, indicating a similar relationship where populations with larger stature were more dimorphic. In this study, we re-examine the hypothesis of an allometric relationship between the sexes using phylogenetic methodology. First, however, we tested whether there exist phylogenetic signals in male and female stature. Data on mean stature from 124 human populations was gathered from the literature. A phylogenetic test showed that male and female stature were significantly associated with phylogeny. These results indicate that comparative methods that to some degree incorporate genetic relatedness between populations are crucial when analyzing human size evolution in a cross-cultural context. Further, neither non-phylogenetic nor phylogenetic analyses revealed any allometric relationship between male and female stature. Thus, we found no support for the idea that sexual dimorphism increases with increasing stature in humans. [Copyright &y& Elsevier]

Presents a phylogenetic reconstruction of the evolution of delayed implantation in the Carnivora. Description of a delayed implantation; Analysis of the differences between mustelids that have delayed implantation and those that do not; Methodology of the study; Results and discussion.

What determines the number of cultural traits present in chimpanzee (Pan troglodytes) communities is poorly understood. In humans, theoretical models suggest that the frequency of cultural traits can be predicted by population size. In chimpanzees, however, females seem to have a particularly important role as cultural carriers. Female chimpanzees use tools more frequently than males. They also spend more time with their young, skewing the infants' potential for social learning towards their mothers. In Gombe, termite fishing has been shown to be transmitted from mother to offspring. Lastly, it is female chimpanzees that transfer between communities and thus have the possibility of bringing in novel cultural traits from other communities. From these observations we predicted that females are more important cultural carriers than males. Here we show that the reported number of cultural traits in chimpanzee communities correlates with the number of females in chimpanzee communities, but not with the number of males. Hence, our results suggest that females are the carriers of chimpanzee culture. [ABSTRACT FROM AUTHOR]

Presents a commentary on the article about violence. Assertion of the author that man is a hunter-killer; Examination on the behavior of primates assimilated to humans; Evidence of the biological background irrelevant on the level of violence that species inflicts on its kin.

When authoritarian regimes liberalize, are there observable patterns in the ordering of reforms, and are these patterns distinct for cases that transition to democracy? While the prevailing literature tends to focus on exogenous 'determinants' of democracy, this letter describes the endogenous dynamics of liberalization itself. Using pairwise domination analysis, it assesses the institutional order of reforms during 371 episodes of liberalization in autocracies between 1900 and 2019. Based on twenty-four indicators of democratic institutions and practices, our findings reveal (1) a clear pattern of reform during liberalization episodes, (2) with strong similarities across outcomes, but also that (3) reforms to the administration of elections tend to develop comparatively earlier in episodes of liberalization that produce a democratic transition. [ABSTRACT FROM AUTHOR]

1. Parasites and infectious diseases have become a major concern in conservation biology, in part because they can trigger or accelerate species or population declines. Focusing on primates as a well-studied host clade, we tested whether the species richness and prevalence of parasites differed between threatened and non-threatened host species. 2. We collated data on 386 species of parasites (including viruses, bacteria, protozoa, helminths and arthropods) reported to infect wild populations of 36 threatened and 81 non-threatened primate species. Analyses controlled for uneven sampling effort and host phylogeny. 3. Results showed that total parasite species richness was lower among threatened primates, supporting the prediction that small, isolated host populations harbour fewer parasite species. This trend was consistent across three major parasite groups found in primates (helminths, protozoa and viruses). Counter to our predictions, patterns of parasite species richness were independent of parasite transmission mode and the degree of host specificity. 4. We also examined the prevalence of selected parasite genera among primate sister-taxa that differed in their ranked threat categories, but found no significant differences in prevalence between threatened and non-threatened hosts. 5. This study is the first to demonstrate differences in parasite richness relative to host threat status. Results indicate that human activities and host characteristics that increase the extinction risk of wild animal species may lead simultaneously to the loss of parasites. Lower average parasite richness in threatened host taxa also points to the need for a better understanding of the cascading effects of host biodiversity loss for affiliated parasite species. [ABSTRACT FROM AUTHOR]

Since the publication of the primate brain volumetric dataset of Stephan and colleagues in the early 1980s, no major new comparative datasets covering multiple brain regions and a large number of primate species have become available. However, technological and other advances in the last two decades, particularly magnetic resonance imaging (MRI) and the creation of institutions devoted to the collection and preservation of rare brain specimens, provide opportunities to rectify this situation. Here, we present a new dataset including brain region volumetric measurements of 39 species, including 20 species not previously available in the literature, with measurements of 16 brain areas. These volumes were extracted from MRI of 46 brains of 38 species from the Netherlands Institute of Neuroscience Primate Brain Bank, scanned at high resolution with a 9.4-T scanner, plus a further 7 donated MRI of 4 primate species. Partial measurements were made on an additional 8 brains of 5 species. We make the dataset and MRI scans available online in the hope that they will be of value to researchers conducting comparative studies of primate evolution. [ABSTRACT FROM AUTHOR]

We present formal evolutionary models for the origins and persistence of the practice of Female Genital Modification (FGMo). We then test the implications of these models using normative cross-cultural data on FGMo in Africa and Bayesian phylogenetic methods that explicitly model adaptive evolution. Empirical evidence provides some support for the findings of our evolutionary models that the de novo origins of the FGMo practice should be associated with social stratification, and that social stratification should place selective pressures on the adoption of FGMo; these results, however, are tempered by the finding that FGMo has arisen in many cultures that have no social stratification, and that forces operating orthogonally to stratification appear to play a more important role in the cross-cultural distribution of FGMo. To explain these cases, one must consider cultural evolutionary explanations in conjunction with behavioral ecological ones. We conclude with a discussion of the implications of our study for policies designed to end the practice of FGMo. [ABSTRACT FROM AUTHOR]

Here we present an analytical technique for the measurement and evaluation of changes in chronologically sequenced assemblages. To illustrate the method, we studied the cultural evolution of European cooking as revealed in seven cook books dispersed over the past 800 years. We investigated if changes in the set of commonly used ingredients were mainly gradual or subject to fashion fluctuations. Applying our method to the data from the cook books revealed that overall, there is a clear continuity in cooking over the ages – cooking is knowledge that is passed down through generations, not something (re-)invented by each generation on its own. Looking at three main categories of ingredients separately (spices, animal products and vegetables), however, disclosed that all ingredients do not change according to the same pattern. While choice of animal products was very conservative, changing completely sequentially, changes in the choices of spices, but also of vegetables, were more unbounded. We hypothesize that this may be due a combination of fashion fluctuations and changes in availability due to contact with the Americas during our study time period. The presented method is also usable on other assemblage type data, and can thus be of utility for analyzing sequential archaeological data from the same area or other similarly organized material. [ABSTRACT FROM AUTHOR]