This commentary welcomes Singh's shift from dual inheritance to individual psychology but argues that his model remains incomplete without evolutionary foundations. Cultural variants are not adopted merely because they appear useful - they appeal to evolved motivational systems shaped by natural selection. Integrating adaptive goals, producer-consumer dynamics, and ecological variation transforms subjective selection into a genuinely evolutionary-ecological framework.

We agree with Levine et al. that moral judgments track outcomes that would emerge from a balanced bargaining process. But we challenge the claim that moral cognition must therefore simulate bargaining itself. Like any evolved system that exploits deep regularities without representing them, moral cognition can produce ideal contractualist judgments without mentally representing bargaining scenarios.

This paper responds to more than twenty commentaries on The Ecological Approach to Culture, written by researchers in evolutionary biology, behavioral ecology, evolutionary anthropology, cognitive science, and evolutionary psychology. We use these commentaries to clarify and expand the framework of cultural ecology. The central claim is that cultural phenomena do not require a distinct inheritance system. Culture emerges from eco-phenotypic feedbacks between evolved psychological mechanisms and ecological legacies—material, informational, and institutional modifications produced by previous generations. Crucially, natural selection designs cognitive systems oriented toward adaptive goals (status, cooperation, mating, coordination, threat management), not fixed cultural behaviors. These systems generate context-dependent, goal-directed solutions: cultural products are constructed phenotypes, not adaptations in their own right. Cultural stability occurs when new generations confront similar constraints and opportunities as previous ones. Cultural change happens when these constraints shift—when incentives, resources, risks, or social opportunities are altered. Treating culture as ecological construction therefore extends the gene-centered logic of behavioral ecology to the cultural domain without invoking cultural replicators or group-level interests. We illustrate the value of this program across domains such as navigation, punitive gods, ritual practices, kinship systems, class-linked behavior, technological innovation, and romantic literature.

Converging evidence shows that the cultural importance of romantic love has increased dramatically with societal development; it now serves as a primary criterion for choosing partners, a foundation for family formation, and a pervasive theme in cultural production. Yet here we show that this rise does not continue indefinitely: romantic love peaks and then declines at the highest levels of development. This rise-and-fall pattern emerges both cross-nationally (9,474 participants across 45 countries) and diachronically (automatic annotations of 13,409 U.S. movies, 1971–2020). This poses a puzzle: if romantic love sustains long-term pair-bonds, and if safer, more affluent environments make such bonds more viable, why would love decline where it should thrive? We resolve this paradox by proposing that what declines is not love itself, but the need to signal it. Using a formal model and cross-national analyses (N=7,333 and 84,382), we show that when long-term commitment becomes common, overt romantic signaling becomes unnecessary and even counterproductive: the most committed individuals benefit from not signaling, because doing so would reveal that they expected the relationship to need reassurance. In affluent societies, love becomes quieter not because bonds are weaker, but because they are more secure.

Why do people prefer certain fictional stories over others? Personality traits capture stable individual differences in motivational sensitivities: Openness reflects exploration, Neuroticism reflects threat-reactivity, and so on. If so, these traits should systematically predict preferences for narrative features that engage the corresponding motivational systems. We test this hypothesis across three preregistered studies. In Study 1, we directly measured individual preferences for motivationally salient narrative features in a cross-cultural survey of 9,201 participants from 23 countries. Personality traits predicted preferences and the overall pattern replicated in 22 of 23 countries. In Study 2, we confirmed these predictions using ecologically valid data from 574 movies, annotated by large language models for the same narrative features and linked to the Big Five profiles of 3.5 million Facebook users. The predicted associations replicated at the population level. In Study 3, we tested a complementary structural prediction: if story preferences reflect an underlying motivational architecture, then the co-occurrence structure of narrative features in stories should mirror the co-preference structure across individuals. Using Mantel tests, we found strong structural correspondence, replicated across all 23 countries. Together, these findings support a model in which story preferences arise from universal motivational systems whose sensitivities vary across individuals.

Why do people become interested in some stories but not others? A long-standing assumption is that narrative engagement is driven by demographic-similarity between the audience and the protagonist. Across two preregistered experiments (N = 953), we systematically manipulated the protagonist’s gender, race, age, and motivation in short story pitches, and asked participants—who varied in their own gender, race, age, and motivational priorities—to rate their interest. This preregistered controlled design allowed us to compare demographic-similarity with a theoretically grounded alternative: motivational alignment, defined as the match between a protagonist’s current motivation and the observer’s own motivational priorities. Motivational alignment reliably predicted narrative interest and remained a significant predictor even when demographic-similarity was included in the same model. We also found no evidence that demographic-similarity predicts interest, even when specific information about the protagonist’s motivation was absent. These findings identify motivational alignment as a central determinant of narrative interest.

Women with a lower waist-to-hip ratio (WHR) are consistently judged as more attractive, a finding replicated across diverse populations and methods. From an evolutionary perspective, this preference may reflect selection for cues of female reproductive potential, as WHR reliably tracks both age and parity. However, virtually all previous studies present nude or minimally clothed bodies in highly standardised conditions, leaving open whether WHR-based judgements generalise to more ecologically valid settings and whether they extend beyond attractiveness to the reproductive traits WHR is a cue of. We addressed both questions by analysing 608 painted female figures from European portraits (1650–1950), depicting fully clothed women in visually complex and minimally sexualised settings. Online Prolific observers (N = 1,525) independently estimated the body shape, attractiveness, age, and likelihood of previous childbirth from either the body or the face of the painted characters. Perceived WHR strongly predicted all three trait judgements: lower WHR was associated with higher attractiveness, younger perceived age, and lower perceived likelihood of previous childbirth. These relationships persisted after controlling for posture, body orientation, perceived weight, perceived facial age, artistic school, and date of the artwork. Our findings show that WHR-based perceptual heuristics are not artefacts of the narrow stimulus conditions used in prior research but persist in visually complex, clothed, and historically diverse depictions of women. They further suggest that fashion styles that exaggerate WHR may have functioned as strategic amplifiers of reproductively relevant cues, with implications for theories of mate choice, social signalling, fashion history and cultural evolution.

We fully share Ko and Neuberg's premises and conclusions. We only suggest that the framework could be further clarified by distinguishing two kinds of inputs: regulatory variables (cues that calibrate motivational salience) and affordances (local action possibilities that matter only once a motivation is already engaged).

Women with a lower waist-to-hip ratio (WHR) are consistently judged as more attractive, a finding replicated across diverse populations and methods. From an evolutionary perspective, this preference may reflect selection for cues of female reproductive potential, as WHR reliably tracks both age and parity. However, virtually all previous studies present nude or minimally clothed bodies in highly standardized conditions, leaving open whether WHR-based judgments generalize to more ecologically valid settings and whether they extend beyond attractiveness to the reproductive traits WHR is a cue of. We addressed both questions by analyzing 608 painted female figures from European portraits (1650–1950), depicting fully clothed women in visually complex and minimally sexualized settings. Online Prolific observers (N = 1,525) independently estimated the body shape, attractiveness, age, and likelihood of previous childbirth from either the body or the face of the painted characters. Perceived WHR strongly predicted all three trait judgments: lower WHR was associated with higher attractiveness, younger perceived age, and lower perceived likelihood of previous childbirth. These relationships persisted after controlling for posture, body orientation, perceived weight, perceived facial age, artistic school, and date of the artwork. Our findings show that WHR-based perceptual heuristics are not artifacts of the narrow stimulus conditions used in prior research but persist in visually complex, clothed, and historically diverse depictions of women. They further suggest that fashion styles that exaggerate WHR may have functioned as strategic amplifiers of reproductively relevant cues, with implications for theories of mate choice, social signaling, fashion history and cultural evolution.

Humans are capable of remarkably flexible moral judgment. Yet societies rely on rigid rules-obligations and prohibitions that apply categorically, even when case-by-case reasoning could yield better outcomes. Why would a species capable of flexibility bind itself to rigid rules? We propose that rigid rules arise as social technologies for managing ambiguity about noncooperation. People often have legitimate reasons for failing to cooperate, yet those reasons are typically opaque to observers, allowing opportunists to disguise selfishness as justified hardship. We formalize this idea with a game-theoretic model. Two cooperative equilibria emerge: a flexible norm that accommodates legitimate excuses but is vulnerable to exploitation, and a rigid norm that closes this loophole by mandating cooperation even when inefficient. Comparing these equilibria reveals an efficiency-robustness trade-off: Flexibility maximizes welfare when trust is secure, whereas rigidity preserves cooperation when trust is fragile. This explains why rigid rules prevail in interactions with strangers, formal institutions, or in tight societies, while flexibility is more common when trust is secure.

Individualism, the prioritization of personal distinctiveness over group conformity, is theorized to increase with economic development. This study tests this hypothesis over a century (1900–2022) across 95 French départements, using name uniqueness as a behavioral proxy. We first validate this proxy at the subnational level, showing that name uniqueness correlates with regional survey-based individualism indices (World Values Survey), even after controlling for immigration rates. Using complete civil registry data (N ≈ 79 million) and a bootstrapped name uniqueness score, we then analyze its relationship with economic development across space and time. Our analysis yields three key findings. First, longitudinal analysis reveals a strong positive association: as GDP per capita increased nationally over the 100-year period, name uniqueness rose significantly across all départements. Second, after removing shared temporal trends by standardizing variables within each year, effectively treating départements (n = `r nobs(norm_model_boy)`) as small, culturally and socially identical countries, GDP per capita continues to predict higher name uniqueness. Third, we uncover nuanced patterns: the relationship was moderated by gender, particularly during the World Wars, and rising economic inequality between regions was accompanied by growing divergence in naming practices, suggesting that development drives both cultural individualism and cultural stratification. Together, these results provide robust, fine-grained evidence that economic development fosters a cultural shift toward greater individualism.

Individuals high in Openness to Experience are more likely to enjoy imaginary worlds, visit museums, be vaccinated, support redistribution, endorse animal rights, and volunteer, alongside a wide array of other characteristic behaviors. Although these behaviors appear disparate, we propose that they form a coherent constellation grounded in a tendency to explore the unknown and tolerate uncertainty. This clarifies why levels of Openness vary across individuals, groups, and historical periods: exploration is modulated by ecological conditions such as safety and resource availability. When environments make exploration worthwhile, Openness expands; when conditions are harsh or precarious, it contracts. Consequently, ecological differences should generate systematic differences in cultural forms. This framework explains how ecological conditions shape culture through their effects on personality.

Empirical and theoretical work shows that poverty has a wide range of effects on psychological and behavioral outcomes such as temporal discounting and risk taking. However, much less attention has been given to the relationship between socio-economic conditions and personality traits. To address this gap, we conducted a cross-classified meta-analysis of 141 effect sizes from 84 independent studies, examining the relationship between socio-economic conditions and Big Five personality traits. We relied on two types of measures: parental socio-economic status at the individual level, and regional or national indicators, such as GDP per capita, at the aggregate level. Building on a behavioral-ecological framework informed by life history theory, which treats socio-economic conditions as ecological inputs involved in the calibration of psychological traits, we hypothesized that people living in resource-rich ecologies would score higher on Big Five personality traits (extraversion, openness to experience, agreeableness, conscientiousness and emotional stability). Consistent with these predictions, more favorable socio-economic conditions during childhood predicted greater extraversion, openness to experience, agreeableness, and emotional stability at the individual level, as well as higher extraversion and emotional stability at the aggregate level. Although the underlying evidence is correlational, the observed pattern of associations is consistent with the hypothesis that resource availability plays a systematic role in the calibration of personality traits.

We present a comprehensive analysis of the rise of fictions across human narratives, using large-scale datasets that collectively span over 65,000 works across various media (movies, literary works), cultures (over 30 countries, Western and non-Western), and time periods (2000 BCE to 2020 CE). We measured fictiveness - defined as the degree of departure from reality - across three narrative dimensions: protagonists, events, and settings. We used automatic annotations from large language models (LLMs) to systematically score fictiveness and ensured the robustness and validity of our measure, specifically by demonstrating predictable variations in fictiveness across different genres, in all media. Statistical analyses of the changes in fictiveness over time revealed a steady increase, culminating in the 20th and 21st centuries, across all narrative forms. Remarkably, this trend is also evident in our data spanning ancient times: fictiveness increased gradually in narratives dating back as far as 2000 BCE, with notable peaks of fictiveness during affluent periods such as the heights of the Roman Empire, the Tang Dynasty, and the European Renaissance. We explore potential psychological explanations for the rise in fictiveness, including changing audience preferences driven by ecological and social changes.

Why do humans believe in moralizing gods? Leading accounts argue that these beliefs evolved because they help societies grow and promote group cooperation. Yet recent evidence suggests that beliefs in moralizing gods are not limited to large societies and might not have strong effects on cooperation. Here, we propose that beliefs in moralizing gods develop because individuals shape supernatural beliefs to achieve strategic goals in within-group interactions. People have a strategic interest in controlling others' cooperation, either to extort benefits from them or to gain reputational benefits for protecting the public good. Moreover, they believe, based on their folk-psychology, that others would be less likely to cheat if they feared supernatural punishment. Thus, people endorse beliefs in moralizing gods to manipulate others into cooperating. Prosocial religions emerge from a dynamic of mutual monitoring, in which each individual, lacking confidence in the cooperativeness of conspecifics, attempts to incentivize others' cooperation by endorsing beliefs in supernatural punishment. We show how variations of this incentive structure explain the variety of cultural attractors toward which supernatural punishment converges, including extractive religions that extort benefits from exploited individuals, prosocial religions geared toward mutual benefit, and forms of prosocial religion where belief in moralizing gods is itself a moral duty. We review evidence for nine predictions of this account and use it to explain the decline of prosocial religions in modern societies. Supernatural punishment beliefs seem endorsed as long as people believe them necessary to ensure others' cooperation, regardless of their objective effectiveness in doing so. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Research in social cognition suggests that intentions play a fundamental role in moral judgements. This study leverages computational text analysis of over 250,000 U.S. congressional speeches from 1880 to 2020 to examine the evolution of intentionality framing—rhetoric focusing on immigrants' motives, desires, and goals. Using GPT-4 to identify intentionality cues, we find a significant increase in intentionality framing since the mid-20th century, coinciding with growing polarization between Democrats and Republicans. Crucially, pro-immigration discourse increasingly emphasizes positive intentions, while anti-immigration rhetoric has become more behaviorist, focusing on external impacts rather than internal states. This rhetorical divergence intensifies during periods of heightened political polarization. Our findings highlight how political actors strategically mobilize psychological intuitions about intent to mobilize voter support and underscore the role of perceived intentionality in shaping social and moral evaluations of immigrant groups.

The prevailing view in the literature treats cultural dynamics as fundamentally distinct from other ecological processes—governed by a second system of inheritance and requiring a separate set of theoretical foundations. Yet at its core, culture is simply an emergent outcome of interactions among individuals and with their shared environment—the very kind of phenomenon ecologists routinely study. In fact, in many ecosystems not considered cultural, such interactions do produce stable population differences, rapid innovations, informational changes, or even cumulative dynamics. These phenomena are more pronounced in cultural ecosystems, but they are not different in kind. Accordingly, we argue that cultural ecosystems should be studied through the same mechanisms as other ecosystems—ecological modifications, phenotypic responses, legacy effects, and ecological cascades. Different ecosystems may require specific methods or concepts, but not fundamentally different theoretical frameworks. The main strength of this deflationary view of culture lies in its parsimony. If culture is not fundamentally special, we can rely on the same robust and well-tested framework—namely, inclusive fitness theory—to understand human behavior in cultural ecosystems, just as we do for animal behavior more generally. Inclusive fitness theory, in turn, can help explain both (i) individual behavior in culturally rich ecosystems and (ii) how the interaction of such behaviors gives rise to the large-scale ecological patterns we call culture.

This study investigates the historical evolution of individualism by analysing trends in Name Uniqueness — the distinctiveness of personal names — as a proxy for values emphasising autonomy, independence and self-expression. Using a dataset of 2313,713 notable individuals from Wikidata (1500–2000), we aimed to capture the historic evolution of Name Uniqueness in the Western hemisphere. Our analysis reveals an increase in individualism in Europe, the Americas, and Australia that predates widespread modernisation, which aligns with the conclusions of historians. In line with modernisation theory, we also observe a strong positive correlation between GDP per capita and Name Uniqueness across five centuries. These results remain robust when controlling for gender, occupation, and time period. Our findings challenge Max Weber’s thesis that the spread of Protestantism is associated with an increase in individualism; in fact, we find that it is associated with a decrease. By combining large-scale historical data with a validated cultural indicator, this study contributes to the growing body of evidence linking economic development to profound shifts in identity and social behaviour. It highlights Name Uniqueness as a powerful tool for tracing the long-term dynamics of individualism in large scale societies.

Modernization refers to the shift from traditional values to individual autonomy and self-development, driven by economic development. Previously considered unique to Western culture, modernization has now emerged as a global phenomenon, with East Asia playing a leading role. This article explores the possibility that modernization might have occurred outside the Western world prior to Western influence. We pioneered a novel approach for understanding the evolution of Chinese values by creating a unique and comprehensive database of narrative fiction. This database includes all major Chinese narrative fiction from the Tang dynasty (7th century) to the present, encompassing 3,496 works from mainland China and 3,338 modern works from Singapore, Taiwan, and Hong Kong. It also provides a systematic comparison of ancient fictions and their modern adaptations (e.g., Journey to the West ). Our findings confirm that modernization has been underway in China since the late twentieth century. Surprisingly, a similar rise in modern values was detected as early as the seventeenth and eighteenth centuries, coinciding with significant economic development. This era saw an increasing expression of romantic love, open-mindedness, and reciprocal cooperation. However, this shift was not sustained, leading to a significant reassertion of traditional values from the late eighteenth century until the early twentieth century. These findings not only highlight the nuanced dynamics of early modernization beyond Western contexts but also demonstrate that values are dynamic, evolving constantly in response to economic development, thereby challenging the binary distinction between WEIRD (Western, Educated, Industrialized, Rich and Democratic) and non-WEIRD societies.

A well-established finding in Evolutionary Behavioural Sciences is that a low waist-to-hip ratio (WHR) is judged as more attractive than a high WHR in women, a preference hypothesised to track female mate value. However, virtually all studies on the topic display nude or minimally clothed bodies, under highly standardised conditions, potentially exaggerating WHR’s influence in real-world contexts. We tested whether WHR-based judgements generalise to fully clothed women and to more ecologically valid conditions by analysing 608 painted female figures from European portraits (1650–1950), embedded in socially rich, minimally sexualised settings. Online Prolific observers (N = 1,525) independently estimated the body shape, attractiveness, age, and likelihood of previous childbirth from either the body or the face of the painted characters. Perceived WHR strongly predicted trait judgements: lower WHR was associated with higher attractiveness, younger perceived age, and lower perceived likelihood of previous childbirth. These relationships persisted after controlling for various variables, including posture, body orientation, perceived weight, and perceived facial age. Our findings show that WHR-based heuristics persist even in visually complex, clothed, and historically diverse depictions of women. They further suggest that fashion styles that exaggerate WHR may have functioned as strategic amplifiers of socially and reproductively relevant cues, with implications for theories of mate choice, social signalling, fashion history and cultural evolution.