Traditional creative occupations ('artists' & 'authors') were associated with elevated genetic risk for a range of psychiatric disorders, but similar, or greater elevations were seen for religious, helping and teaching professions

Is an elevated family-genetic risk for major psychiatric disorders specific to creative occupations? Kenneth S. Kendler et al. Psychological Medicine, Jun 8 2022. https://www.cambridge.org/core/journals/psychological-medicine/article/abs/is-an-elevated-familygenetic-risk-for-major-psychiatric-disorders-specific-to-creative-occupations/003E0401E67E8FD52BA96B4A1C6BEDAB

Abstract

Background: Despite a large descriptive literature linking creativity and risk for psychiatric illness, the magnitude and specificity of this relationship remain controversial.

Methods: We examined, in 1 137 354 native Swedes with one of 59 3-digit official and objective occupational codes in managerial and educated classes, their familial genetic risk score (FGRS) for ten major disorders, calculated from 1st through 5th degree relatives. Mean FGRS across disorders were calculated, in 3- and 4-digit occupational groups, and then controlled for those whose disorder onset preceded occupational choice. Using sequential analyses, p values were evaluated using Bonferroni correction.

Results: 3-digit professions considered to reflect creativity (e.g. ‘artists’ and ‘authors’) were among those with statistically significant elevations of FGRS. Among more specific 4-digit codes, visual artists, actors, and authors stood out with elevated genetic risks, highest for major depression (MD), anxiety disorders (AD) and OCD, more modest for bipolar disorders (BD) and schizophrenia and, for authors, for drug and alcohol use disorders. However, equal or greater elevations in FGRS across disorders were seen for religious (e.g. ministers), helping (e.g. psychologists, social workers), and teaching/academic occupations (e.g. professors). The potential pathway from FGRS → Disorder → Occupation accounts for a modest proportion of the signal, largely for MD and AD risk.

Conclusions: While traditional creative occupations were associated with elevated genetic risk for a range of psychiatric disorders, this association was not unique, as similar, or greater elevations were seen for religious, helping and teaching professions and was stronger for internalizing than psychotic disorders.

We found women’s ideas to be more original during ovulation compared to non-fertile phases of the ovulatory cycle

Enhanced Originality of Ideas in Women During Ovulation: A Within-Subject Design Study. Katarzyna Galasinska and Aleksandra Szymkow. Front. Psychol., June 9 2022 | https://doi.org/10.3389/fpsyg.2022.859108

Abstract: The signaling theory suggests that creativity may have evolved as a signal for mates. Indeed, its aesthetic value might not have been necessary for survival, but it could have helped to attract a mate, fostering childbearing. If we consider creativity as such a signal, we should expect it will be enhanced in the context related to sexual selection. This hypothesis was tested mainly for men. However, both men and women display physical and mental traits that can attract a mate. Previous studies showed that women can be more creative during their peak fertility. We advanced these findings in the present study, applying reliable measures of menstrual cycle phases (examining saliva and urine samples) and the highly recommended within-subject design. We also introduced and tested possible mediators of the effect. We found women’s ideas to be more original during ovulation compared to non-fertile phases of the ovulatory cycle. The results are discussed in the context of signaling theory and alternative explanations are considered.

Discussion

The aim of the research was to replicate the study investigating enhanced creative potential of fertile women, with the use of more reliable measures of the phases, and more appropriate within-subject design. We tested women during follicular, ovulation, and luteal phases, hypothesizing to find the effect during ovulation. Our hypotheses were based on the signaling theory (Miller, 2000a), which states that creativity may have evolved as a signal for mates. Although we cannot confirm its role as an indicator of fitness, our study suggests that it may be a mental ornament in women, related to the process of sexual selection (Darwin, 1871). Such an ornament should be manifested in the contexts associated with mating, like, for example, during a fertile phase of the ovulatory cycle.

In our study, originality of ideas was enhanced among fertile women. Originality is called an impression stimulator (Runco, 2007), as it affects attention. This sort of saliency starts at the sensory level (Gaspelin and Luck, 2018). As the most captivating feature of creativity, originality is also found to be the strongest predictor of it (Diedrich et al., 2015). There are also various ways to achieve original ideas. Flexibility of thinking can lead to such ideas through breaking patterns (Runco, 2007). In our study, flexibility was not differentiated in the comparison of three phases. But, it was higher during fertile phase, compared to less fertile phases combined. Different processes may also foster originality, for example persistence (Nijstad et al., 2010). Further studies are needed to test this idea. The fluency dimension was not differentiated either. The probability to generate an original idea increases with the number of ideas. However, the number of ideas is not essential, as a creative person may produce only one idea, but it may be an original one (Acar et al., 2017). Women had a similar quantity, but different quality of ideas. Furthermore, this quantity was quite high in each phase (about 11 ideas on average per phase), so we can assume that participants were generally motivated to produce ideas in the study. We cannot exclude the influence of the pandemic, as partial isolation might have affected participants’ willingness to engage in any kind of activities related to the outside world, creative activities in particular (Karwowski et al., 2021). This generic increased motivation may have also influenced diversity of their thoughts (flexibility), as this dimension was also not differentiated between phases. However, such motivation was not sufficient to produce similarly original ideas in each phase. Thus, it is difficult to interpret differences in originality between phases in the context of isolation, as it was a fixed condition across the phases. Female’s fertility and cycle length are considered to be affected due to illness (Carp-Veliscu et al., 2022) or vaccination (Nguyen et al., 2021). However, the study was conducted in the pre-vaccine (for COVID-19) period. None of the screened participants reported being sick. Morbidity rates during that time were relatively low when we compare them to the following years. However, we cannot exclude asymptomatic cases of COVID-19. We want to emphasize that we did not investigate creativity in participants whose ovulatory cycle was disturbed. The length of all screened cycles was differentiated within a range from 27 to 35 days, so we did not observe notable changes in the cycle length, in the cases when ovulation normally occurred.

Miller (2000a) outlines that creativity, as a subject of selection, concerns a domain associated with aesthetics and fine arts rather than technological innovation. Darwin (1871) pointed to a ‘sense of beauty,’ suggesting a mechanism for mere aesthetics with no direct benefits. Wallace, on the contrary, pointed to the good-gene, utilitarian model, suggesting signals of vigor and vitality behind the signals of beauty, which started a debate on how exactly the mechanisms of sexual and natural selection interact (Prum, 2012; Hoquet and Levandowsky, 2015). Creative ideas are domain-general and defined as novel and useful (Runco, 2007). However, studies indicate that the effect of novelty is larger than usefulness and the latter is not necessarily predictive of creativity (Diedrich et al., 2015). It is also hard to miss the difference between technology and fine arts. The common variance of creativity and intelligence is found to be moderate, and researchers outline the orthogonality of these two constructs (Runco, 2007). Technological creativity would more likely fit the Wallacean utilitarian view of sexual selection processes (Feist, 2001). As divergent and original thinking is assumed to be independent of IQ (Wallach and Kogan, 1965), in our study we have additionally involved a creative convergent thinking test, reflecting the correlation of creativity and intelligence (Lee et al., 2014), and hence more relevant to survival problem solving. Eventually, we found no differences in these abilities between phases. It leads us to an interesting conclusion, corresponding to the problem of utility or/and beauty aspects of sexual selection. Namely, it is possible that convergent creativity could rather be attributed to natural selection processes, while divergent creativity to sexual selection understood after Darwin (1871) as a non-utilitarian, merely aesthetic mechanism of evolution. Thus, our study suggests that two different types of creativity might have evolved, each one focused on solving problems in different domains, namely survival and reproduction. If so, we should expect divergent creativity, but not the convergent one, to be enhanced in the mating context. This is to be verified in future studies.

The significant role of possible mediators would suggest that creativity may be a by-product of another selection. We tested arousal and positive mood, as they can facilitate creativity (Baas et al., 2008). Men could choose women who were more aroused, or more joyful, not directly creative. Creativity, as facilitated by elevated and activating moods, could have developed in parallel. However, although we found these variables increased during the fertile phase (vs infertile phases), we did not detect any mediating effects. Furthermore, both energetic and tense dimensions of mood were the highest during the luteal phase. However, being asked about general arousal, women reported it to be lower comparing to ovulation. We can suppose that during the luteal phase, women experienced mixed emotions. Progesterone may be associated with PMS syndrome (van Wingen et al., 2008), which we did not control unfortunately. But, as estrogen and progesterone act together during the luteal phase, we cannot exclude their interaction in affecting mood in the way we observed. It is important to note, that we awaited the LH peak during ovulation in our study, which usually co-occurs with a pending decrease of estrogen (Reed and Carr, 2018). Direct hormonal measures are needed to explain the mood effects we obtained.

Fertile phase arousal may manifest differently: as a general arousal on the physiological level, but also as mental, sexual, or motoric stimulation, or even as a motivational boost. It is possible, therefore, that the measures we administered might have not been precise enough and they should be more diversified in future studies. We did not control for premenstrual syndrome, which can also be a confounding variable. Finally, we did not control for typing speed (Forthmann et al., 2017), nor the time of day (Breslin, 2019).2

We did not find any differences in cognitive control between the phases; however, this result should be taken with caution. The conditions were not standardized, as the study procedure was conducted via the Internet. Participants’ PC monitors may differ in size and contrast. Additionally, we were not able to check if all participants did the training as we recommended.

To sum up, the present study replicated the effect of enhanced originality of ideas among women during ovulation (Galasinska and Szymkow, 2021). It suggests that originality in divergent creativity is a plausible candidate for mental ornamentation in women. Being boosted during the fertile phase of the cycle, originality presumably increases mate attraction, potentially leading to conception. Nevertheless, it may also promote intrasexual competition to discourage competitors. More contexts should be studied to confirm the hypothesis on the signaling role of creativity. We presented just one of them, showing that with no other incentives, women may manifest some signals of creativity, which may point to its evolutionary legacy.

The belief in free will can be manipulated, showing an increase of deterministic beliefs, but there are no downstream consequences for world views, attitudes or behavior

Manipulating Belief in Free Will and Its Downstream Consequences: A Meta-Analysis. Oliver Genschow et al. Personality and Social Psychology Review, June 8, 2022. https://doi.org/10.1177/10888683221087527

Abstract: Ever since some scientists and popular media put forward the idea that free will is an illusion, the question has risen what would happen if people stopped believing in free will. Psychological research has investigated this question by testing the consequences of experimentally weakening people’s free will beliefs. The results of these investigations have been mixed, with successful experiments and unsuccessful replications. This raises two fundamental questions: Can free will beliefs be manipulated, and do such manipulations have downstream consequences? In a meta-analysis including 145 experiments (95 unpublished), we show that exposing individuals to anti–free will manipulations decreases belief in free will and increases belief in determinism. However, we could not find evidence for downstream consequences. Our findings have important theoretical implications for research on free will beliefs and contribute to the discussion of whether reducing people’s belief in free will has societal consequences.

Keywords: free will, determinism, belief, meta-analysis, morality, cheating, social behavior, punishment

Progressives selected a more unflattering portrait of a typical conservative face than traditional liberals

The Progressive Values Scale: Assessing the Ideological Schism on the Left. Travis Proulx et al. Personality and Social Psychology Bulletin, June 8, 2022. https://doi.org/10.1177/01461672221097529

Abstract: Progressivism has increasingly challenged traditional liberalism as the dominant influence within left-wing ideology. Across four studies, we developed a measure—the Progressive Values Scale (PVS)—that characterizes distinctly progressive values within the left-wing. In Study 1, left-wing participants evaluated divisive issues, with four scale factors emerging. In Study 2, we confirmed this factor structure and included a battery of personality and values measures to explore individual differences among those who maintain a progressive worldview. In Study 3, we achieved final confirmation of the factor structure and validated the ability of the PVS to assess a distinctly progressive perspective, insofar as progressives generated prototypical faces for Liberals and Conservatives that were markedly distinct from those generated by traditional liberals. In Study 4, we distinguished the PVS from measures of left-wing authoritarianism and demonstrated that it is a better predictor of progressive political preferences and social judgments.

Keywords: political psychology, progressivism, liberalism, assessment, values, personality

The effects of computer-mediated communication on well-being get smaller the closer one looks at them

Computer-Mediated Communication and Well-Being in the Age of Social Media: A Systematic Review. Andrew C High et al. Journal of Social and Personal Relationships, June 8, 2022. https://doi.org/10.1177/02654075221106449

Abstract: The association between computer-mediated communication (CMC) and well-being is a complex, consequential, and hotly debated topic that has received significant attention from pundits, researchers, and the media. Conflicting research findings and fear over negative outcomes have spurred both moral panic and further research into these associations. To create a more comprehensive picture of trends, explanations, and future directions in this domain of research, we conducted a systematic meso-level review of 366 studies across 349 articles published since 2007 that report associations between CMC and well-being. Although most of this research is not explicitly theoretical, several potential theoretical mechanisms for positive and negative effects of CMC on well-being are utilized. The heterogeneity of effects in the studies we reviewed could be explained by the discipline in which the research is conducted, the methodology used, the types of CMC and well-being examined, and the population studied. Our evaluation of this body of research highlights the importance of attending to how we conceptualize communication and well-being, the questions we ask, and the populations and contexts we study when both reading and producing research on CMC and well-being.

Keywords: Computer-mediated communication, well-being, social media, mental well-being, subjective well-being, physical well-being

Conclusions and implications

It is important that scholars follow the evidence rather than the moral panic of the moment. The goal of this review was to provide a broad picture of how the link between CMC and well-being has been studied and how researchers can use this information to most productively build on the current body of literature. Studies of CMC and well-being have been conducted across a range of disciplines, though primarily in psychology, communication studies, medicine, and business. Of note is our observation that disciplinary differences were reflected in divergent findings. The tendency for positive and negative effects to vary by discipline is probably related to the different types of questions researchers ask. For example, studies in communication often focused on positive behaviors such as social support, whereas studies in psychology often examined behaviors associated with poorer well-being, such as addiction and social comparison. We also found that populations that experience stigma or social isolation often benefit from the connection that CMC can provide. In contrast, studies on adolescents, tend to find negative effects, potentially due to their vulnerability to cyberbullying or social comparison. The bulk of what we know, however, relies on Western and Asian samples with good access to CMC, and the few studies that examine other populations suggest that effects might differ for them.

Throughout our meso-level review, we highlighted findings observed within underrepresented populations. In many ways, these findings can be divided into groups with easy access to technology (e.g., adolescents) compared to groups who have recently gained access (e.g., older individuals, people who live in isolated areas). Although some of these novel samples produce distinct findings, many of them fit within larger themes. People who have ready access to technology often exhibit varied but small effects. Immersed in social technologies, they may identify negative repercussions of using technology as particularly salient while positive or neutral effects fade into the background of their daily life. In contrast, people who are isolated, whether because of marginalization or physical locale, often perceive CMC to be beneficial, at least early in its reception.

Rather than focusing on single aspects of identity, future research can take intersectionality more seriously. Although there are many studies on adolescents and some studies on underrepresented cultures and ethnic groups, there are few studies on adolescents from minority groups that focus on the lived experiences of these groups (for exceptions, see Baxter, 2017; Stanton et al., 2017). Further considering multiple aspects of identity, particularly underrepresented or marginalized identities, allows scholars to extend research on topics like cyberbullying or exclusion to consider whether negative outcomes are particularly bad for certain groups (e.g., Black adolescents). Alternatively, perhaps the benefits of social capital or social support are especially valued by the same groups. Taken together, these trends point to the need to contextualize both positive and negative findings relative to each other, the populations within which they occur, the intersectionality inherent in people’s identities, and the wide range of other behaviors that contribute to or detract from well-being. Meier and Reinecke (2021) proposed a six-level hierarchical taxonomy to understand different levels through which CMC can be analyzed. The current meso-level review largely focused on what they labeled the application, branded application, and function levels, while also incorporating additional aspects of research that are not included in their taxonomy. Future research can enhance understanding of the connections between CMC and well-being by examining the intersections among different levels of Meier and Reinecke’s (2021) taxonomy alongside other influential aspects of this domain of research.

As we have outlined above, the link between CMC and well-being appears to be generally small and heterogeneous. This conclusion does not minimize the importance of studying that link. Some populations, such as those who are socially isolated, appear to benefit greatly from the ability to connect with others online. Conversely, some CMC behaviors (e.g., upward social comparison and cyberbullying) are consistently associated with poorer well-being. For people who experience less dramatic effects of CMC, its pervasiveness in everyday life means that even small effects can be consequential. As CMC becomes more embedded in how we relate to and communicate with others, it becomes increasingly important to understand when, how, and for whom CMC use is related to enhanced or impaired well-being. Moreover, it is paramount that researchers understand what people are saying and doing in these channels. Our examination of the literature suggests that we can more precisely account for the associations between CMC and well-being by more carefully considering the questions we ask, the populations in which we ask them, the communication that happens in CMC, its relational and cultural contexts, and the ways we conceptualize well-being.

Individuals steadily have grown less conscientiousness and more neurotic since the beginning of the pandemic

Berg, Cameron. 2022. “Personality Trends over the COVID-19 Pandemic.” PsyArXiv. June 8. doi:10.31234/osf.io/9mu46

Abstract: The COVID-19 pandemic has exhibited significant psychological and behavioral impacts, but a precise account of the way that the pandemic has altered human personality is still highly uncertain. This investigation leverages a dataset of Five Factor Model (“Big Five”) personality results from 2.8-million US adults recorded throughout the duration of the pandemic in order to better understand the relationship between significant COVID-19 trends and population-level trait measurements. Using ordinary correlational and more sophisticated machine learning (ML) techniques, we find that (1) individuals steadily have grown less conscientious and more neurotic since the beginning of the pandemic, that (2) average population-level measures of trait agreeableness increased most strongly in response to shorter-term, transient worsening of the pandemic (e.g., hospitalization spikes), while average population-level measures of trait neuroticism increased most strongly in response to longer-term, cumulative worsening of the pandemic (e.g., total deaths), that (3) average population-level measures of trait openness significantly decreased in response to the shorter-term, transient worsening of the pandemic, and that (4) on average, ML-generated regression models were able to explain approximately half of the variance in population-level trait trajectories solely given regressors associated with the course of the COVID-19 pandemic (e.g., the number of people admitted into the ICU for COVID-19 on a given day of the pandemic). Taken together, these findings are among the first to suggest that, at the population level, the COVID-19 pandemic exhibited specific, measurable, and durable impacts on human personality.

Stronger sex drive in men compared to women, with a medium-to-large effect size: Men more often think and fantasize about sex, more often experience sexual affect like desire, and more often engage in masturbation than women

Frankenbach, Julius, Marcel Weber, David D. Loschelder, Helena Kilger, and Malte Friese. 2022. “Sex Drive: Theoretical Conceptualization and Meta-analytic Review of Gender Differences.” PsyArXiv. June 8. doi:10.31234/osf.io/9yk8e

Abstract: Few spheres in life are as universally relevant for (almost) all individuals past puberty as sexuality. One important aspect of sexuality concerns individuals’ sex drive—their dispositional sexual motivation. A vigorous scientific (and popular) debate revolves around the question of whether or not there is a gender difference in sex drive. Several theories predict a higher sex drive in men compared to women, with some theories attributing this difference to biased responding rather than true differences. Currently, there is little consensus on how to conceptualize sex drive, nor does a quantitative summary of the literature exist. In this paper, we present a theory-driven conceptualization of sex drive as the density distribution of state sex drive, where state sex drive is defined as momentary sexual motivation that manifests in sexual cognition, affect, and behavior. We conduct a comprehensive meta-analysis of gender differences in sex drive based on 211 studies, 856 effect sizes, and 621,463 persons. The meta-analysis revealed a stronger sex drive in men compared to women, with a medium-to-large effect size (g = 0.69, CI95 [0.58, 0.81]). Men more often think and fantasize about sex, more often experience sexual affect like desire, and more often engage in masturbation than women. Adjustment for biased responding reduced the gender difference (g = 0.54). Moderation analyses suggest that the effect is robust and largely invariant to contextual factors. There was no evidence of publication bias. The discussion focuses on validity considerations, limitations, and implications for psychological theory and people’s everyday lives.

Jazz musicians were less conscientious and more open to experience than classical musicians

The musician’s personality: Do personality traits vary according to ensemble membership? Zahava L Heydel, Randyl D Smith, Nels Grevstad. Psychology of Music, June 6, 2022. https://doi.org/10.1177/03057356221096779

Abstract: Despite many decades’ worth of investigations into associations between music and personality, the empirical findings are quite scant and scattered. Perhaps, this is because musicians are a diverse group of people, with far-reaching musical interests and wide-ranging personalities. Little research, however, has investigated whether musicians’ choice of musical genre bears a relationship to their personalities. In this study, we explore the limited literature on the relationship between music ensemble membership and personality by investigating personality differences between jazz and classical ensemble musicians on the Big Five personality dimensions. Musicians (N = 221) were recruited from college music ensembles, an introductory psychology course, a Facebook page, and Amazon Mechanical Turk. Participants completed the Big Five Inventory (BFI), a validated self-report personality questionnaire, and analyses were conducted to compare the scores of jazz musicians to the scores of classical musicians. Significant differences emerged between jazz and classical musicians’ personalities, with gender playing a mediating role. These results may be beneficial for music educators and directors, as knowledge that specific personality traits predict music ensemble membership may help guide instruction techniques, communication, understanding between musicians of different musical genres, and general cooperation between music educators/directors and their ensembles.

Keywords: musicians, personality, classical musician, jazz musician, Big Five model

The evolutionary novelty of childcare by and with strangers: Net of education, earnings, sex, current marital status, and number of children, more intelligent British parents were more likely to resort to paid childcare at ages 33 & 42

The evolutionary novelty of childcare by and with strangers. Satoshi Kanazawa. Journal of Experimental Child Psychology, Volume 221, September 2022, 105432. https://doi.org/10.1016/j.jecp.2022.105432

Abstract: Alloparenting by and with genetically unrelated individuals is evolutionarily novel; thus, the Savanna–IQ Interaction Hypothesis predicts that more intelligent parents are more likely to resort to paid childcare by strangers. Analyses of individual data (National Child Development Study) in the United Kingdom (Study 1) and macrolevel data from the United States (Study 2) and economically developed Organization for Economic Cooperation and Development (OECD) nations (Study 3) confirmed the hypothesis. Net of education, earnings, sex, current marital status, and number of children, more intelligent British parents were more likely to resort to paid childcare at ages 33 and 42; net of female labor force participation rate, median household income, median cost of childcare, and mean education, U.S. states with higher average intelligence had higher proportions of children (ages 0–4) in paid childcare; and net of maternal employment, gross domestic product (GDP) per capita, cost of childcare, and female educational attainment, OECD nations with higher average intelligence had higher proportions of infants (ages 0–2) in paid childcare. The results were remarkably consistent; both across the 50 U.S. states and 45 economically developed OECD nations, a one IQ point increase in the average intelligence of the population was associated with a 1.8% increase in the proportion of children in paid childcare. Contrary to earlier findings, there was some suggestive evidence that the experience of paid daycare might harm the cognitive development of children. The studies point to the importance of evolutionary perspective in developmental psychology and child development.

Keywords: Day careChild careIsraeli kibbutzimTaiwanese sim pua marriagesIncest avoidanceWestermarck effect

Unambiguous chickens were not present until ∼1650 to 1250 BCE in central Thailand; production and storage of rice & millet may have acted as a magnet, thus initiating the chicken domestication process

The biocultural origins and dispersal of domestic chickens. Joris Peters et al. Proceedings of the National Academy of Sciences, 119 (24) e2121978119, June 6, 2022. https://doi.org/10.1073/pnas.2121978119

Significance: Chickens are the world’s most numerous domestic animal. In order to understand when, where, and how they first became associated with human societies, we critically assessed the domestic status of chicken remains described in >600 sites in 89 countries, and evaluated zoogeographic, morphological, osteometric, stratigraphic, contextual, iconographic, and textual data. Although previous studies have made claims for an early origin of chickens, our results suggest that unambiguous chickens were not present until ∼1650 to 1250 BCE in central Thailand. A correlation between early chickens and the first appearance of rice and millet cultivation suggests that the production and storage of these cereals may have acted as a magnet, thus initiating the chicken domestication process.

Abstract: Though chickens are the most numerous and ubiquitous domestic bird, their origins, the circumstances of their initial association with people, and the routes along which they dispersed across the world remain controversial. In order to establish a robust spatial and temporal framework for their origins and dispersal, we assessed archaeological occurrences and the domestic status of chickens from ∼600 sites in 89 countries by combining zoogeographic, morphological, osteometric, stratigraphic, contextual, iconographic, and textual data. Our results suggest that the first unambiguous domestic chicken bones are found at Neolithic Ban Non Wat in central Thailand dated to ∼1650 to 1250 BCE, and that chickens were not domesticated in the Indian Subcontinent. Chickens did not arrive in Central China, South Asia, or Mesopotamia until the late second millennium BCE, and in Ethiopia and Mediterranean Europe by ∼800 BCE. To investigate the circumstances of their initial domestication, we correlated the temporal spread of rice and millet cultivation with the first appearance of chickens within the range of red junglefowl species. Our results suggest that agricultural practices focused on the production and storage of cereal staples served to draw arboreal red junglefowl into the human niche. Thus, the arrival of rice agriculture may have first facilitated the initiation of the chicken domestication process, and then, following their integration within human communities, allowed for their dispersal across the globe.

Discussion

Assessing the Spatiotemporal Pattern of Chicken Domestication.

Two initial hypotheses proposed separate temporal and geographic origins of domestic chickens. Zeuner (5) argued that domestic chickens were present in the Indus Valley during the mature Harappan period (∼2600 to 1900 BCE) and subsequently introduced to Mesopotamia. Based upon the presumption that archaeological bird remains dated to the sixth millennium BCE in Neolithic northern China were chickens, West and Zhou (6) claimed that chicken domestication must have taken place in Southeast Asia prior to this before being translocated into China, and then farther west following a northern route. A more recent study concluded that red junglefowl were domesticated in the Yellow River basin shortly after the onset of the Holocene (8) (SI Appendix, Table S1).

With respect to South Asia, the claim that chickens were present within the Indus Valley Civilization was based upon two bone remains from Harappa (25) and four from Mohenjo-daro (24), as well as an incomplete “hen” figurine from Mohenjo-daro (23, 79). Our reanalysis of the two Harappan bones shows that one is morphologically inconsistent with Gallus, and the other’s taxonomic classification is ambiguous. The taxonomic classification of three of the four fragmentary bird bones from Mohenjo-daro is also questionable. In addition, all of these bones, including a completely preserved femur, pertain to individuals that significantly exceed the size of prehistoric chickens. Finally, all four specimens have been collected in upper strata. Given the propensity for chicken bones to move between stratigraphic boundaries (13), it’s possible these remains are recent intrusions. These lines of evidence call into question the assumption that poultry farming was present in Bronze Age Mohenjo-daro (SI Appendix, Table S3).

Excavations conducted in other Indus Valley Civilization sites and contemporaneous settlements produced additional chicken bones, especially in Saraushtra (SI Appendix, Fig. S2). These specimens were classified as domestic fowl based on the absence of modern wild jungle fowl populations in the region (22) and the aforementioned incorrect claim for fowl husbandry in the Indus Valley. Although currently located beyond the present-day natural distribution of both red and gray junglefowl (Fig. 1 and SI Appendix, Fig. S1), this region shares similar ecological characteristics and borders the region where gray junglefowl is extant (80). It is therefore likely that the natural range of gray junglefowl extended into the Indus River basin during the Mid-Holocene, and that these remains derive instead from local wild populations. This conclusion is supported by the presence of other fauna present in zooarchaeological assemblages, or in Harappan art (including Indian Hog Deer: Axis porcinus; Swamp Deer: Cervus duvauceli; and the Indian Rhinoceros: Rhinoceros unicornis), indicating relatively larger distributions of several fauna in the past (81). The combined weight of this evidence suggests that, contrary to the long-standing hypothesis, chickens were not domesticated in the Indus Valley.

Regarding northern China, subsequent reevaluations of the galliform remains (1, 9), as well as photographs and drawings, demonstrate that they are pheasant bones (2, 82). In addition, high-resolution climate and precipitation records from temperate Holocene East Asia, and the habitat requirements of the vertebrate taxa associated with the pheasants, suggest that the subtropical forest habitat conducive to thermophilic red junglefowl did not extend into northern China during the Holocene climatic optimum (1). Finally, mitochondrial analyses of modern breeds support a late dispersal scenario of chickens into northern China (83). Our analysis thus supports a much later arrival in this region consistent with the first appearance of chickens in Japan in the early first millennium CE, and in Mongolia during the early second millennium CE.

Our combined reanalyses of zooarchaeological, linguistic, genetic, and iconographic evidence suggests the following scenario. The first chickens were likely derived from a population of the subspecies G. gallus spadiceus, whose current range spans southwestern China, northern Thailand, and Myanmar (16) (Fig.1). The first unambiguous chicken bones in the archaeological record are present within the faunal assemblage at Neolithic Ban Non Wat in central Thailand, and date to ∼1650 to 1250 BCE. Once incorporated into human societies, chickens dispersed into and beyond the range of other Gallus subspecies and species. The evidence presented here demonstrates that chickens did not appear in archaeological contexts within Central China, South Asia, or Mesopotamia until the late second millennium BCE, just before their initial presence in Melanesia. By ∼700 BCE, chickens had arrived in Ethiopia and Mediterranean Europe (Fig. 2). This western dispersal was substantially more rapid than the establishment of chicken populations in temperate regions present in higher latitudes (Fig. 2). Overall, our analyses indicate a temporal origin and spread of chickens that substantially postdates many of those suggested by previous studies (6, 8).

A Hypothesis for the Process of Chicken Domestication.

Within the native range of red junglefowl, many Southeast Asian languages refer to chickens as “bamboo fowl,” given how readily they take advantage of cyclical bamboo mass flowering and seeding events (10). Red junglefowl are also known to consume rice grains (Oryza sp.) (44, 84), a staple dietary component of Southeast Asian domestic chickens (85). Rice and millet (Setaria italica) were cultivated by mixed foraging and cereal producing Neolithic communities in mainland Southeast Asia (86–88). An analysis of the material culture (including pottery decoration) associated with these agriculturalists suggests that rice and millet cultivating communities dispersed from the Yangtze valley (89–92) into southern China, where they arrived by the mid-third millennium BCE (90, 93). From there, they continued into peninsular Southeast Asia, where people following distinct dispersal pathways emphasized either rice or millet (94).

Land reclamation for cereal cultivation led to the replacement of primary forest by secondary vegetation, a habitat more suitable for red junglefowl. Outside of bamboo thickets, red junglefowl are known to thrive in slash-and-burn agricultural systems (10). The novel presence of cultivated fields, fallow fields (necessary for either millet or rainfed rice), cereal harvest residues, remainders of human food preparation and consumption, invertebrates associated with keeping pigs and cattle, and other aspects of the human niche may have attracted red junglefowl to human settlements and their immediate catchment.

The long-term abundance of cereals within the human niche would have led to dramatic shifts in selective pressure that lasted multiple generations, including a relaxation of selection against larger clutch size, as well as increased selection against territoriality in cocks (10). These conditions likely also facilitated larger bird population densities near farming communities, followed by subsequent “accommodation” of birds within the village. The availability of cultivated cereals may have therefore catalyzed a shift in the relationship between people and red junglefowl consistent with the commensal pathway (95, 96).

The current archaeobotanical evidence indicates that sites with rice cultivation appeared within the distribution of G. gallus spadiceus [the subspecies recently identified as the most likely progenitor of chickens (16)] from about 2000 BCE in two regions: southern Yunnan and northeast Thailand (Fig. 3 and SI Appendix, Table S4). Although cereal farming was also present at this time within the inferred distributions of Gallus gallus jabouillei and G. gallus gallus, there is as yet no evidence for the early presence of domestic chicken populations. Although there is confirmation of early rice farming near coastal areas and in low-lying wetlands (86, 94), the zooarchaeological records in Neolithic Vietnam, for example, show evidence for the hunting of wetland birds, but lack remains of Gallus (97). In more interior zones, early rainfed rice/millet cultivation likely spurred a tighter relationship between people and G. gallus spadiceus, as attested by the earliest confirmed chicken bones at Ban Non Wat and Non Nok Tha (SI Appendix, Table S2) (98). Because the rice was rainfed, it would have required more land area and fallow cycles relative to later, more productive irrigated rice (87), and these conditions would have created large areas of secondary thicket vegetation. In the northern region of the G. gallus spadiceus distribution, similar processes were likely possible, but detailed avifaunal studies at prehistoric archaeological sites in Yunnan have not yet been carried out.

Fig. 3.

A map depicting the distribution of dated archaeological rice finds taken from the revised Rice Archaeological Database compiled by D.Q.F. and colleagues, RAD 2.0 (90), with newly added archaeological records and cleaned reports with associated dates that appear too early based on current understanding of archaeological chronology. This is especially the case in mainland Southeast Asia where most of the arrival of cereal agriculture is now thought to be ∼2500 BC for northern Vietnam and southernmost China only and ∼2000 BC for the rest of the region (94, 123).

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In regions north of Yunnan, wet rice agriculture, characterized by small-scale, intensive wetland fields in the Yangtze (87, 99), is present as early as 4000 to 3000 BCE, and these wet paddyfield systems spread throughout central China during the Neolithic. Chickens, however, were absent in the Neolithic (100) and only appear ∼1000 BCE (Fig. 3). Relative to wet rice, dry rice and millet cultivation that predominate in the tropical south is characterized by more extensive mosaics of field and fallow, a niche more suited to wild and commensal red junglefowl.

A Combined Chicken–Rice Dispersal Across Asia and Africa.

Following the integration of chickens and human agricultural societies, the correlated spatiotemporal patterns of rice and chicken dispersal across Asia is striking. In South Asia for example, sedentism became widespread in the Ganges plains in the second millennium BCE (22, 101), and domesticated rice, wheat, barley, and other grain crops began to dominate the economy (102, 103). At this time, agriculture in the Deccan focused on small millets, beans, and occasionally wheat and barley (22, 101). It is during this period, perhaps from the later second millennium BCE, that the subsistence context would have been ideal for chickens or commensal jungle fowl, and this timing corresponds with the arrival of bird remains unambiguously identified as chickens in the Indian subcontinent.

While there is evidence for proto-indica rice management by hunter–fisher–gatherers in the middle Ganges plains predating ∼2000 BCE (102, 104, 105), proto-indica rice was managed in natural, seasonal wetlands that were unlikely to attract Gallus in large numbers. This is illustrated by a dearth of Gallus remains and a low level of both cereal production and livestock husbandry in the archaeological record (22). The domesticated indica rice introduced ∼1600 to 1500 BCE in the Upper and Middle Ganges (104, 105) was typically rainfed in more extensive systems with periods of fallow (102, 106), and thus more attractive to fowl. Recent genomic evidence derived from modern populations suggested that although modern domestic chickens in South Asia possess signatures associated with the local subspecies G. gallus murghi, these ancestral affinities are the result not of a local, independent domestication process, but the result of admixture with introduced domestic chickens derived from G. gallus spadiceus (16).

In Iron Age Mesopotamia, rice and millet cultivation may also have been linked to the initiation and intensification of poultry farming. For example, the cultivation of Chinese millets (Panicum miliaceum, Setaria italica) began in the later second millennium BCE (107–109) and intensified after ∼1000 BCE (110, 111), precisely when poultry husbandry becomes visible archaeologically (Fig. 2 and SI Appendix, Table S2). Middle Assyrian texts also confirm that irrigated rice became established in Syria by ∼1100 BCE, and references to this practice increased from the eighth century BCE (112). Thus, alongside the diversification of grain crops, chickens may represent an additional element of the broadening of Near Eastern subsistence practices after the late Bronze Age collapse (45).

There is also a correlation in Africa between the appearance of chickens and rice agriculture. The translocation of chickens to coastal Southeast Africa and the Indian Ocean islands in the eighth/ninth centuries CE coincides with the introduction of Asian crops, such as rice, tree cotton, and mung bean (113). In addition, archaeobotanical evidence in the Niger Basin illustrates the prominent role of cereal diversification, including more widespread rice cultivation and increasing urbanism ∼300 to 900 CE (114), a temporal window that coincides with the first appearance of chickens.