What is universal about music, and what varies? We built a corpus of ethnographic text on musical behavior from a representative sample of the world’s societies, as well as a discography of audio recordings. The ethnographic corpus reveals that music (including songs with words) appears in every society observed; that music varies along three dimensions (formality, arousal, religiosity), more within societies than across them; and that music is associated with certain behavioral contexts such as infant care, healing, dance, and love. The discography—analyzed through machine summaries, amateur and expert listener ratings, and manual transcriptions—reveals that acoustic features of songs predict their primary behavioral context; that tonality is widespread, perhaps universal; that music varies in rhythmic and melodic complexity; and that elements of melodies and rhythms found worldwide follow power laws.

Are humans too generous? The discovery that subjects choose to incur costs to allocate benefits to others in anonymous, one-shot economic games has posed an unsolved challenge to models of economic and evolutionary rationality. Using agent-based simulations, we show that such generosity is the necessary byproduct of selection on decision systems for regulating dyadic reciprocity under conditions of uncertainty. In deciding whether to engage in dyadic reciprocity, these systems must balance (i) the costs of mistaking a one-shot interaction for a repeated interaction (hence, risking a single chance of being exploited) with (ii) the far greater costs of mistaking a repeated interaction for a one-shot interaction (thereby precluding benefits from multiple future cooperative interactions). This asymmetry builds organisms naturally selected to cooperate even when exposed to cues that they are in oneshot interactions.altruism | cooperation | ecological rationality | social evolution | evolutionary psychology H uman behavior in all known cultures is densely interpenetrated by networks of reciprocity or exchange (to use the terms of biologists and economists, respectively). Fueled by these observations, biologists and game theorists developed models that outlined how the fitness benefits to be reaped from gains in trade can, under the right envelope of conditions, drive the evolution of decision-making adaptations for successfully engaging in direct reciprocity (1-5). Indeed, a broad array of experimental and neuroscientific evidence has accumulated over the last two decades supporting the hypothesis that our species' decision-making architecture includes both cognitive and motivational specializations whose design features are specifically tailored to enable gains through direct reciprocity (e.g., detection of defectors and punitive sentiment toward defectors) (6-16).The most important condition necessary for the evolution of direct reciprocity is that interactions between pairs of agents be sufficiently repeated (2). For reciprocity to operate, after one agent delivers a benefit, the partner must forgo the immediate gain offered by cheating-that is, of not incurring the cost involved in returning a comparable benefit. In general, selection can only favor forgoing this gain and incurring the cost of reciprocating when the net value to the partner of the future series of exchange interactions (enabled by reciprocation) exceeds the benefit of immediate defection (which would terminate that future series). If there were no future exchanges-if an interaction was one-shotthen the equilibrium strategy would be always defect. However, both direct observations and the demographic conditions that characterize hunter-gatherer life indicate that large numbers of repeat encounters, often extending over decades, was a stable feature of the social ecology of ancestral humans (17).Despite this close fit between theory and data for direct reciprocity, problems emerged in closely related issues. In particular, when experimentalists bega...

Music comprises a diverse category of cognitive phenomena that likely represent both the effects of psychological adaptations that are specific to music (e.g., rhythmic entrainment) and the effects of adaptations for non-musical functions (e.g., auditory scene analysis). How did music evolve? Here, we show that prevailing views on the evolution of music — that music is a byproduct of other evolved faculties, evolved for social bonding, or evolved to signal mate quality — are incomplete or wrong. We argue instead that music evolved as a credible signal in at least two contexts: coalitional interactions and infant care. Specifically, we propose that (1) the production and reception of coordinated, entrained rhythmic displays is a co-evolved system for credibly signaling coalition strength, size, and coordination ability; and (2) the production and reception of infant-directed song is a co-evolved system for credibly signaling parental attention to secondarily altricial infants. These proposals, supported by interdisciplinary evidence, suggest that basic features of music, such as melody and rhythm, result from adaptations in the proper domain of human music. The adaptations provide a foundation for the cultural evolution of music in its actual domain, yielding the diversity of musical forms and musical behaviors found worldwide.

Humans use music for a variety of social functions: we sing to accompany dance, to soothe babies, to heal illness, to communicate love, and so on. Across animal taxa, vocalization forms are shaped by their functions, including in humans. Here, we show that vocal music exhibits recurrent, distinct, and cross-culturally robust form-function relations that are detectable by listeners across the globe. In Experiment 1, internet users (n = 750) in 60 countries listened to brief excerpts of songs, rating each song's function on six dimensions (e.g., "used to soothe a baby"). Excerpts were drawn from a geographically stratified pseudorandom sample of dance songs, lullabies, healing songs, and love songs recorded in 86 mostly small-scale societies, including hunter-gatherers, pastoralists, and subsistence farmers. Experiment 1 and its analysis plan were pre-registered. Despite participants' unfamiliarity with the societies represented, the random sampling of each excerpt, their very short duration (14 s), and the enormous diversity of this music, the ratings demonstrated accurate and cross-culturally reliable inferences about song functions on the basis of song forms alone. In Experiment 2, internet users (n = 1,000) in the United States and India rated three contextual features (e.g., gender of singer) and seven musical features (e.g., melodic complexity) of each excerpt. The songs' contextual features were predictive of Experiment 1 function ratings, but musical features and the songs' actual functions explained unique variance in function ratings. These findings are consistent with the existence of universal links between form and function in vocal music.

One sentence summary: Ethnographic text and audio recordings map out universals and variation in world music. Abstract:What is universal about music, and what varies? We built a corpus of ethnographic text on musical behavior from a representative sample of the world's societies, and a discography of audio recordings. The ethnographic corpus reveals that music appears in every society observed; that music varies along three dimensions (formality, arousal, religiosity), more within societies than across them; and that music is associated with certain behavioral contexts such as infant care, healing, dance, and love. The 2 discography, analyzed through machine summaries, amateur and expert listener ratings, and manual transcriptions, revealed that acoustic features of songs predict their primary behavioral context; that tonality is widespread, perhaps universal; that music varies in rhythmic and melodic complexity; and that melodies and rhythms found worldwide follow power laws. Main Text:At least since Henry Wadsworth Longfellow declared in 1835 that "music is the universal language of mankind" (1) the conventional wisdom among many authors, scholars, and scientists is that music is a human universal, with profound similarities across societies springing from shared features of human psychology (2). On this understanding, musicality is embedded in the biology of Homo sapiens(3), whether as one or more evolutionary adaptations for music (4, 5), the byproducts of adaptations for auditory perception, motor control, language, and affect (6-9), or some amalgam.Music certainly is widespread (10-12), ancient (13), and appealing to almost everyone (14). Yet claims that it is universal or has universal features are commonly made without citation (e.g., (15-17)), and those with the greatest expertise on the topic are skeptical. With a few exceptions (18), most music scholars, particularly ethnomusicologists, suggest there are few if any universals in music (19)(20)(21)(22)(23). They point to variability in the interpretations of a given piece of music (24-26), the importance of natural, political, and economic environments in shaping music (27)(28)(29), the diverse forms of music that can share similar behavioral functions (30), and the methodological difficulty of comparing the music of different societies (12,31,32). Given these criticisms, along with a history of some scholars using comparative work to advance erroneous claims of cultural or racial superiority (33), the common view among music scholars today (34,35) is summarized by the ethnomusicologist George List: "The only universal aspect of music seems to be that most people make it. … I could provide pages of examples of the nonuniversality of music. This is hardly worth the trouble." (36) Are there, in fact, meaningful universals in music? No one doubts that music varies across cultures, but diversity in behavior can shroud regularities emerging from common underlying psychological mechanisms. Beginning with Noam Chomsky's hypothesis that the world's languages 3 ...