Global musical diversity is largely independent of linguistic and genetic histories.

Music is a universal yet diverse cultural trait transmitted between generations. The extent to which global musical diversity traces cultural and demographic history, however, is unresolved. Using a global musical dataset of 5242 songs from 719 societies, we identify five axes of musical diversity and show that music contains geographical and historical structures analogous to linguistic and genetic diversity. After creating a matched dataset of musical, genetic, and linguistic data spanning 121 societies containing 981 songs, 1296 individual genetic profiles, and 121 languages, we show that global musical similarities are only weakly and inconsistently related to linguistic or genetic histories, with some regional exceptions such as within Southeast Asia and sub-Saharan Africa. Our results suggest that global musical traditions are largely distinct from some non-musical aspects of human history.

Effects of Voice Pitch on Social Perceptions Vary With Relational Mobility and Homicide Rate.

Fundamental frequency ( fo) is the most perceptually salient vocal acoustic parameter, yet little is known about how its perceptual influence varies across societies. We examined how fo affects key social perceptions and how socioecological variables modulate these effects in 2,647 adult listeners sampled from 44 locations across 22 nations. Low male fo increased men's perceptions of formidability and prestige, especially in societies with higher homicide rates and greater relational mobility in which male intrasexual competition may be more intense and rapid identification of high-status competitors may be exigent. High female fo increased women's perceptions of flirtatiousness where relational mobility was lower and threats to mating relationships may be greater. These results indicate that the influence of fo on social perceptions depends on socioecological variables, including those related to competition for status and mates.

Universal interpretations of vocal music.

Despite the variability of music across cultures, some types of human songs share acoustic characteristics. For example, dance songs tend to be loud and rhythmic, and lullabies tend to be quiet and melodious. Human perceptual sensitivity to the behavioral contexts of songs, based on these musical features, suggests that basic properties of music are mutually intelligible, independent of linguistic or cultural content. Whether these effects reflect universal interpretations of vocal music, however, is unclear because prior studies focus almost exclusively on English-speaking participants, a group that is not representative of humans. Here, we report shared intuitions concerning the behavioral contexts of unfamiliar songs produced in unfamiliar languages, in participants living in Internet-connected industrialized societies (n = 5,516 native speakers of 28 languages) or smaller-scale societies with limited access to global media (n = 116 native speakers of three non-English languages). Participants listened to songs randomly selected from a representative sample of human vocal music, originally used in four behavioral contexts, and rated the degree to which they believed the song was used for each context. Listeners in both industrialized and smaller-scale societies inferred the contexts of dance songs, lullabies, and healing songs, but not love songs. Within and across cohorts, inferences were mutually consistent. Further, increased linguistic or geographical proximity between listeners and singers only minimally increased the accuracy of the inferences. These results demonstrate that the behavioral contexts of three common forms of music are mutually intelligible cross-culturally and imply that musical diversity, shaped by cultural evolution, is nonetheless grounded in some universal perceptual phenomena.

Cross-national analyses require additional controls to account for the non-independence of nations.

Cross-national analyses test hypotheses about the drivers of variation in national outcomes. However, since nations are connected in various ways, such as via spatial proximity and shared cultural ancestry, cross-national analyses often violate assumptions of non-independence, inflating false positive rates. Here, we show that, despite being recognised as an important statistical pitfall for over 200 years, cross-national research in economics and psychology still does not sufficiently account for non-independence. In a review of the 100 highest-cited cross-national studies of economic development and values, we find that controls for non-independence are rare. When studies do control for non-independence, our simulations suggest that most commonly used methods are insufficient for reducing false positives in non-independent data. In reanalyses of twelve previous cross-national correlations, half of the estimates are compatible with no association after controlling for non-independence using global proximity matrices. We urge social scientists to sufficiently control for non-independence in cross-national research.

Gods are watching and so what? Moralistic supernatural punishment across 15 cultures.

Psychological and cultural evolutionary accounts of human sociality propose that beliefs in punitive and monitoring gods that care about moral norms facilitate cooperation. While there is some evidence to suggest that belief in supernatural punishment and monitoring generally induce cooperative behaviour, the effect of a deity's explicitly postulated moral concerns on cooperation remains unclear. Here, we report a pre-registered set of analyses to assess whether perceiving a locally relevant deity as moralistic predicts cooperative play in two permutations of two economic games using data from up to 15 diverse field sites. Across games, results suggest that gods' moral concerns do not play a direct, cross-culturally reliable role in motivating cooperative behaviour. The study contributes substantially to the current literature by testing a central hypothesis in the evolutionary and cognitive science of religion with a large and culturally diverse dataset using behavioural and ethnographically rich methods.

Validating the dual evolutionary foundations of political values in a US sample.

Psychological research repeatedly identifies two dimensions of political values. Recent work argues that these dimensions reflect the dual evolutionary foundations of human social and political life: a trade-off between cooperation and competition that generates differences in values about social inequality, and a trade-off in managing group coordination that generates differences in values about social control. Existing scales used to measure political values, however, were created prior to this framework. Here, we introduce the Dual Foundations Scale, designed to capture values about the two trade-offs. We validate the scale across two studies, showing it accurately and reliably measures both dimensions. Our results support key predictions of the dual foundations framework and pave the way for future work on the foundations of political ideology.

Language trees with sampled ancestors support a hybrid model for the origin of Indo-European languages.

The origins of the Indo-European language family are hotly disputed. Bayesian phylogenetic analyses of core vocabulary have produced conflicting results, with some supporting a farming expansion out of Anatolia ~9000 years before present (yr B.P.), while others support a spread with horse-based pastoralism out of the Pontic-Caspian Steppe ~6000 yr B.P. Here we present an extensive database of Indo-European core vocabulary that eliminates past inconsistencies in cognate coding. Ancestry-enabled phylogenetic analysis of this dataset indicates that few ancient languages are direct ancestors of modern clades and produces a root age of ~8120 yr B.P. for the family. Although this date is not consistent with the Steppe hypothesis, it does not rule out an initial homeland south of the Caucasus, with a subsequent branch northward onto the steppe and then across Europe. We reconcile this hybrid hypothesis with recently published ancient DNA evidence from the steppe and the northern Fertile Crescent.

Cooperative and conformist behavioural preferences predict the dual dimensions of political ideology.

Decades of research suggest that our political differences are best captured by two dimensions of political ideology. The dual evolutionary framework of political ideology predicts that these dimensions should be related to variation in social preferences for cooperation and group conformity. Here, we combine data from a New Zealand survey and a suite of incentivised behavioural tasks (n = 991) to test whether cooperative and conformist preferences covary with a pair of widely used measures of the two dimensions of political ideology-Social Dominance Orientation (SDO) and Right Wing Authoritarianism (RWA)-and related policy views. As predicted, we find that cooperative behaviour is negatively related to SDO and economically conservative policy views, while conformist behaviour in the form of social information use is positively related to RWA and socially conservative policy views. However, we did not find the predicted relationships between punitive and rule following behaviours and RWA or socially conservative views, raising questions about the interpretation of punishment and rule following tasks and the nature of authoritarian conformist preferences. These findings reveal how cooperative and conformist preferences that evolved to help us navigate social challenges in our ancestral past continue to track our political differences even today.

Valence-dependent mutation in lexical evolution.

A central goal of linguistics is to understand how words evolve. Past research has found that macro-level factors such as frequency of word usage and population size explain the pace of lexical evolution. Here we focus on cognitive and affective factors, testing whether valence (positivity-negativity) explains lexical evolution rates. Using estimates of cognate replacement rates for 200 concepts on an Indo-European language tree spanning six to ten millennia, we find that negative valence correlates with faster cognate replacement. This association holds when controlling for frequency of use, and follow-up analyses show that it is most robust for adjectives ('dirty' versus 'clean'; 'bad' versus 'good'); it does not consistently reach statistical significance for verbs, and never reaches significance for nouns. We also present experiments showing that individuals are more likely to replace words for negative versus positive concepts. Our findings suggest that emotional valence affects micro-level guided variation, which drives macro-level valence-dependent mutation in adjectives.

Coevolution of religious and political authority in Austronesian societies.

Authority, an institutionalized form of social power, is one of the defining features of the large-scale societies that evolved during the Holocene. Religious and political authority have deep histories in human societies and are clearly interdependent, but the nature of their relationship and its evolution over time is contested. We purpose-built an ethnographic dataset of 97 Austronesian societies and used phylogenetic methods to address two long-standing questions about the evolution of religious and political authority: first, how these two institutions have coevolved, and second, whether religious and political authority have tended to become more or less differentiated. We found evidence for mutual interdependence between religious and political authority but no evidence for or against a long-term pattern of differentiation or unification in systems of religious and political authority. Our results provide insight into how political and religious authority have worked synergistically over millennia during the evolution of large-scale societies.

Cooperative phenotype predicts climate change belief and pro-environmental behaviour.

Understanding the psychological causes of variation in climate change belief and pro-environmental behaviour remains an urgent challenge for the social sciences. The "cooperative phenotype" is a stable psychological preference for cooperating in social dilemmas that involve a tension between individual and collective interest. Since climate change poses a social dilemma on a global scale, this issue may evoke similar psychological processes as smaller social dilemmas. Here, we investigate the relationships between the cooperative phenotype and climate change belief and behaviour with a representative sample of New Zealanders (N = 897). By linking behaviour in a suite of economic games to self-reported climate attitudes, we show robust positive associations between the cooperative phenotype and both climate change belief and pro-environmental behaviour. Furthermore, our structural equation models support a motivated reasoning account in which the relationship between the cooperative phenotype and pro-environmental behaviour is mediated by climate change belief. These findings suggest that common psychological mechanisms underlie cooperation in both micro-scale social dilemmas and larger-scale social dilemmas like climate change.

Acoustic regularities in infant-directed speech and song across cultures.

When interacting with infants, humans often alter their speech and song in ways thought to support communication. Theories of human child-rearing, informed by data on vocal signalling across species, predict that such alterations should appear globally. Here, we show acoustic differences between infant-directed and adult-directed vocalizations across cultures. We collected 1,615 recordings of infant- and adult-directed speech and song produced by 410 people in 21 urban, rural and small-scale societies. Infant-directedness was reliably classified from acoustic features only, with acoustic profiles of infant-directedness differing across language and music but in consistent fashions. We then studied listener sensitivity to these acoustic features. We played the recordings to 51,065 people from 187 countries, recruited via an English-language website, who guessed whether each vocalization was infant-directed. Their intuitions were more accurate than chance, predictable in part by common sets of acoustic features and robust to the effects of linguistic relatedness between vocalizer and listener. These findings inform hypotheses of the psychological functions and evolution of human communication.

Sequence alignment of folk song melodies reveals cross-cultural regularities of musical evolution.

Culture evolves,1-5 but the existence of cross-culturally general regularities of cultural evolution is debated.6-8 As a diverse but universal cultural phenomenon, music provides a novel domain to test for the existence of such regularities.9-12 Folk song melodies can be thought of as culturally transmitted sequences of notes that change over time under the influence of cognitive and acoustic/physical constraints.9-15 Modeling melodies as evolving sequences constructed from an "alphabet" of 12 scale degrees16 allows us to quantitatively test for the presence of cross-cultural regularities using a sample of 10,062 melodies from musically divergent Japanese and English (British/American) folk song traditions.17,18 Our analysis identifies 328 pairs of highly related melodies, finding that note changes are more likely when they have smaller impacts on a song's melody. Specifically, (1) notes with stronger rhythmic functions are less likely to change, and (2) note substitutions are most likely between neighboring notes. We also find that note insertions/deletions ("indels") are more common than note substitutions, unlike genetic evolution where the reverse is true. Our results are consistent across English and Japanese samples despite major differences in their scales and tonal systems. These findings demonstrate that even a creative art form such as music is subject to evolutionary constraints analogous to those governing the evolution of genes, languages, and other domains of culture.

Shared cultural ancestry predicts the global diffusion of democracy.

Understanding global variation in democratic outcomes is critical to efforts to promote and sustain democracy today. Here, we use data on the democratic status of 221 modern and historical nations stretching back up to 200 years to show that, particularly over the last 50 years, nations with shared linguistic and, more recently, religious ancestry have more similar democratic outcomes. We also find evidence that for most of the last 50 years the democratic trajectory of a nation can be predicted by the democratic status of its linguistic and, less clearly, religious relatives, years and even decades earlier. These results are broadly consistent across three democracy indicators (Polity 5, Vanhanen's Index of Democracy, and Freedom in the World) and are not explained by geographical proximity or current shared language or religion. Our findings suggest that deep cultural ancestry remains an important force shaping the fortunes of modern nations, at least in part because democratic norms, institutions, and the factors that support them are more likely to diffuse between close cultural relatives.

Challenging the Idea That Humans Are Not Designed to Solve Climate Change.

In the face of a slow and inadequate global response to anthropogenic climate change, scholars and journalists frequently claim that human psychology is not designed or evolved to solve the problem, and they highlight a range of "psychological barriers" to climate action. Here, we critically examine this claim and the evidence on which it is based. We identify four key problems with attributing climate inaction to "human nature" or evolved psychological barriers: (a) It minimizes variability within and between populations; (b) it oversimplifies psychological research and its implications for policy; (c) it frames responsibility for climate change in terms of the individual at the expense of the role of other aspects of culture, including institutional actors; and (d) it rationalizes inaction. For these reasons, the message from social scientists must be clear-humans' current collective failure to tackle climate change on the scale required cannot be explained as a product of a universal and fixed human nature because it is a fundamentally cultural phenomenon, reflecting culturally evolved values, norms, institutions, and technologies that can and must change rapidly.

The dual evolutionary foundations of political ideology.

Research over the last fifty years has suggested that political attitudes and values around the globe are shaped by two ideological dimensions, often referred to as economic and social conservatism. However, it remains unclear why this ideological structure exists. Here we highlight the striking concordance between these dual dimensions of ideology and independent convergent evidence for two key shifts in the evolution of human group living. First, humans began to cooperate more and across wider interdependent networks. Second, humans became more group-minded, conforming to social norms in culturally marked groups and punishing norm-violators. We propose that fitness trade-offs and behavioural plasticity have maintained functional variation in willingness to cooperate and conform within modern human groups, naturally giving rise to the two dimensions of political ideology. Supported by evidence from across the behavioural sciences, this evolutionary framework provides insight into the biological and cultural basis of political ideology.

Coding culture: challenges and recommendations for comparative cultural databases.

Considerable progress in explaining cultural evolutionary dynamics has been made by applying rigorous models from the natural sciences to historical and ethnographic information collected and accessed using novel digital platforms. Initial results have clarified several long-standing debates in cultural evolutionary studies, such as population origins, the role of religion in the evolution of complex societies and the factors that shape global patterns of language diversity. However, future progress requires recognition of the unique challenges posed by cultural data. To address these challenges, standards for data collection, organisation and analysis must be improved and widely adopted. Here, we describe some major challenges to progress in the construction of large comparative databases of cultural history, including recognising the critical role of theory, selecting appropriate units of analysis, data gathering and sampling strategies, winning expert buy-in, achieving reliability and reproducibility in coding, and ensuring interoperability and sustainability of the resulting databases. We conclude by proposing a set of practical guidelines to meet these challenges.

The cultural foundations of modern democracies.

National democracy is a rare thing in human history and its stability has long been tied to the cultural values of citizens. Yet it has not been established whether changing cultural values made modern democracy possible or whether those values were a response to democratic institutions. Here we combine longitudinal data and cohort information of nearly 500,000 individuals from 109 nations to track the co-evolution of democratic values and institutions over the last century. We find that cultural values of openness towards diversity predict a shift towards democracy and that nations with low institutional confidence are prone to political instability. In addition, the presence of democratic institutions did not predict any substantive changes in the measured cultural values. These results hold accounting for other factors, including gross domestic product per capita and non-independence between nations due to shared cultural ancestry. Cultural values lead to, rather than follow, the emergence of democracy. This indicates that current stable democracies will be under threat, should cultural values of openness to diversity and institutional confidence substantially decline.