{"title":"Kin selection as a modulator of human handedness: sex-specific, parental and parent-of-origin effects.","authors":"Bing Dong, Silvia Paracchini, Andy Gardner","doi":"10.1017/ehs.2024.24","DOIUrl":"10.1017/ehs.2024.24","url":null,"abstract":"<p><p>The frequency of left-handedness in humans is ~10% worldwide and slightly higher in males than females. Twin and family studies estimate the heritability of human handedness at around 25%. The low but substantial frequency of left-handedness has been suggested to imply negative frequency-dependent selection, e.g. owing to a 'surprise' advantage of left-handers in combat against opponents more used to fighting right-handers. Because such game-theoretic hypotheses involve social interaction, here we perform an analysis of the evolution of handedness based on kin-selection, which is understood to play a major role in the evolution of social behaviour generally. We show that: (1) relatedness modulates the balance of right-handedness vs. left-handedness, according to whether left-handedness is marginally selfish vs. marginally altruistic; (2) sex differences in relatedness to social partners may drive sex differences in handedness; (3) differential relatedness of parents and offspring may generate parent-offspring conflict and sexual conflict leading to the evolution of maternal and paternal genetic effects in relation to handedness; and (4) differential relatedness of maternal-origin vs. paternal-origin genes may generate intragenomic conflict leading to the evolution of parent-of-origin-specific gene effects - such as 'genomic imprinting' - and associated maladaptation.</p>","PeriodicalId":36414,"journal":{"name":"Evolutionary Human Sciences","volume":"6 ","pages":"e32"},"PeriodicalIF":2.2,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11418076/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142308695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jenni E Pettay, David A Coall, Mirkka Danielsbacka, Antti O Tanskanen
{"title":"The role of mating effort and co-residence history in step-grandparental investment.","authors":"Jenni E Pettay, David A Coall, Mirkka Danielsbacka, Antti O Tanskanen","doi":"10.1017/ehs.2024.17","DOIUrl":"10.1017/ehs.2024.17","url":null,"abstract":"<p><p>The prevalence of divorce in both parental and grandparental generations has led to a rise in the number of children who now have families that include both biological and step-grandparents. Despite the thorough examination of biological grandparents' contributions in the recent literature, there remains a scarcity of studies focusing on the investment of step-grandparents. Using population-based data from a sample of 2494 parents in Germany, we assessed grandparental investment through financial support and assistance with childcare of grandparents (<i>N</i> = 4238) and step-grandparents (<i>N</i> = 486). The study revealed that step-grandparents provided lower levels of investment in their grandchildren compared with biological grandparents. Furthermore, the study identified that a longer duration of co-residence between step-grandparents and parents earlier in life did not correspond to an increase or decrease in step-grandparental investment. However, investment by separated biological grandparents increased with the increasing length of co-residence with parents. In line with the scarce literature on step-grandparental investment, these findings indicate that mating effort may be the most important motivation for step-grandparental investment.</p>","PeriodicalId":36414,"journal":{"name":"Evolutionary Human Sciences","volume":"6 ","pages":"e27"},"PeriodicalIF":2.6,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11106544/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141076951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The floating duck syndrome: biased social learning leads to effort-reward imbalances.","authors":"Erol Akçay, Ryotaro Ohashi","doi":"10.1017/ehs.2024.20","DOIUrl":"10.1017/ehs.2024.20","url":null,"abstract":"<p><p>An increasingly common phenomenon in modern work and school settings is individuals taking on too many tasks and spending effort without commensurate rewards. Such an imbalance of efforts and rewards leads to myriad negative consequences, such as burnout, anxiety and disease. Here, we develop a model to explain how such effort-reward imbalances can come about as a result of biased social learning dynamics. Our model is based on a phenomenon that on some US college campuses is called 'the floating duck syndrome'. This phrase refers to the social pressure on individuals to advertise their successes but hide the struggles and the effort put in to achieve them. We show that a bias against revealing the true effort results in social learning dynamics that lead others to underestimate the difficulty of the world. This in turn leads individuals to both invest too much total effort and spread this effort over too many activities, reducing the success rate from each activity and creating effort-reward imbalances. We also consider potential ways to counteract the floating duck effect: we find that solutions other than addressing the root cause, biased observation of effort, are unlikely to work.</p>","PeriodicalId":36414,"journal":{"name":"Evolutionary Human Sciences","volume":"6 ","pages":"e30"},"PeriodicalIF":2.2,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11362996/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142113002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vidrige H Kandza, Haneul Jang, Francy Kiabiya Ntamboudila, Sheina Lew-Levy, Adam H Boyette
{"title":"Dyadic inter-group cooperation in shotgun hunting activities in a Congo Basin village.","authors":"Vidrige H Kandza, Haneul Jang, Francy Kiabiya Ntamboudila, Sheina Lew-Levy, Adam H Boyette","doi":"10.1017/ehs.2024.14","DOIUrl":"https://doi.org/10.1017/ehs.2024.14","url":null,"abstract":"<p><p>Understanding the dynamics of inter-group cooperation in human adaptation has been the subject of recent empirical and theoretical studies in evolutionary anthropology, beginning to fill gaps in our knowledge of how interactions across political, economic and social domains can - and often do - lead to stable, large-scale cooperation. Here we investigate dyadic intergroup cooperation in shotgun hunting in the Republic of the Congo. In the Congo Basin, inter-group cooperation between foragers and farmers is at the centre of an exchange system maintained by traditional norms and institutions such as fictive kinship. Here, we focused on what factors predict cooperative shotgun hunting exchanges between BaYaka and Yambe. We conducted structured interviews with 48 BaYaka hunters and 18 Yambe men who organise hunts in a village along the Motaba River. We used Bayesian multilevel regression models to investigate the influence of Yambe and BaYaka attributes on probability of dyadic cooperation. We found that BaYaka men's reputations as skilled hunters and their family size each predicted cooperation in shotgun hunting, whereas there was no effect of Yambe attributes (status, wealth, family size). We discuss the results in terms of evolutionary models of men as hunters and inter-group cooperation, as well as biodiversity conservation implications.</p>","PeriodicalId":36414,"journal":{"name":"Evolutionary Human Sciences","volume":"6 ","pages":"e22"},"PeriodicalIF":2.6,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11058523/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140867637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Arianna Dalzero, Bret A Beheim, Hillard Kaplan, Jonathan Stieglitz, Paul L Hooper, Cody T Ross, Michael Gurven, Dieter Lukas
{"title":"Cross-cousin marriage among Tsimane forager-horticulturalists during demographic transition and market integration.","authors":"Arianna Dalzero, Bret A Beheim, Hillard Kaplan, Jonathan Stieglitz, Paul L Hooper, Cody T Ross, Michael Gurven, Dieter Lukas","doi":"10.1017/ehs.2024.11","DOIUrl":"10.1017/ehs.2024.11","url":null,"abstract":"<p><p>Although still prevalent in many human societies, the practice of cousin marriage has precipitously declined in populations undergoing rapid demographic and socioeconomic change. However, it is still unclear whether changes in the structure of the marriage pool or changes in the fitness-relevant consequences of cousin marriage more strongly influence the frequency of cousin marriage. Here, we use genealogical data collected by the Tsimane Health and Life History Project to show that there is a small but measurable decline in the frequency of first cross-cousin marriage since the mid-twentieth century. Such changes are linked to concomitant changes in the pool of potential spouses in recent decades. We find only very modest differences in fitness-relevant demographic measures between first cousin and non-cousin marriages. These differences have been diminishing as the Tsimane have become more market integrated. The factors that influence preferences for cousin marriage appear to be less prevalent now than in the past, but cultural inertia might slow the pace of change in marriage norms. Overall, our findings suggest that cultural changes in marriage practices reflect underlying societal changes that shape the pool of potential spouses.</p>","PeriodicalId":36414,"journal":{"name":"Evolutionary Human Sciences","volume":"6 ","pages":"e18"},"PeriodicalIF":2.2,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10988167/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140858351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Why cultural distance can promote - or impede - group-beneficial outcomes.","authors":"Bret Alexander Beheim, Adrian Viliami Bell","doi":"10.1017/ehs.2024.8","DOIUrl":"10.1017/ehs.2024.8","url":null,"abstract":"<p><p>Quantifying the distance between cultural groups has received substantial recent interest. A key innovation, borrowed from population genetics, is the calculation of cultural <i>F<sub>ST</sub></i> (<i>CF<sub>ST</sub></i>) statistics on datasets of human culture. Measuring the variance between groups as a fraction of total variance, <i>F<sub>ST</sub></i> is theoretically important in additive models of cooperation. Consistent with this, recent empirical work has confirmed that high values of pairwise <i>CF<sub>ST</sub></i> (measuring cultural distance) strongly predict unwillingness to cooperate with strangers in coordination vignettes. As applications for <i>CF<sub>ST</sub></i> increase, however, there is greater need to understand its meaning in naturalistic situations beyond additive cooperation. Focusing on games with both positive and negative frequency dependence and high-diversity, mixed equilibria, we derive a simple relationship between <i>F<sub>ST</sub></i> and the evolution of group-beneficial traits across a broad spectrum of social interactions. Contrary to standard assumptions, this model shows why <i>F<sub>ST</sub></i> can have both positive and <i>negative</i> marginal effects on the spread of group-beneficial traits under certain realistic conditions. These results provide broader theoretical direction for empirical applications of <i>CF<sub>ST</sub></i> in the evolutionary study of culture.</p>","PeriodicalId":36414,"journal":{"name":"Evolutionary Human Sciences","volume":"6 ","pages":"e14"},"PeriodicalIF":2.6,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10955364/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140185899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Natalia Albuquerque, Carine Savalli, Marina Belli, Ana Clara Varella, Beatriz Felício, Juliana França, Patrícia Izar
{"title":"Erratum: The shape of lipsmacking: socio-emotional regulation in bearded capuchin monkeys (Sapajus libidinosus) - CORRIGENDUM.","authors":"Natalia Albuquerque, Carine Savalli, Marina Belli, Ana Clara Varella, Beatriz Felício, Juliana França, Patrícia Izar","doi":"10.1017/ehs.2024.4","DOIUrl":"10.1017/ehs.2024.4","url":null,"abstract":"<p><p>[This corrects the article DOI: 10.1017/ehs.2023.10.].</p>","PeriodicalId":36414,"journal":{"name":"Evolutionary Human Sciences","volume":"6 ","pages":"e13"},"PeriodicalIF":2.6,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10955351/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140185897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nikhil Chaudhary, Abigail E Page, Gul Deniz Salali, Mark Dyble, Daniel Major-Smith, Andrea B Migliano, Lucio Vinicius, James Thompson, Sylvain Viguier
{"title":"Hunter-Gatherer children's close-proximity networks: Similarities and differences with cooperative and communal breeding systems.","authors":"Nikhil Chaudhary, Abigail E Page, Gul Deniz Salali, Mark Dyble, Daniel Major-Smith, Andrea B Migliano, Lucio Vinicius, James Thompson, Sylvain Viguier","doi":"10.1017/ehs.2024.1","DOIUrl":"10.1017/ehs.2024.1","url":null,"abstract":"<p><p>Among vertebrates, allomothering (non-maternal care) is classified as cooperative breeding (help from sexually mature non-breeders, usually close relatives) or communal breeding (shared care between multiple breeders who are not necessarily related). Humans have been described with both labels, most frequently as cooperative breeders. However, few studies have quantified the relative contributions of allomothers according to whether they are (a) sexually mature and reproductively active and (b) related or unrelated. We constructed close-proximity networks of Agta and BaYaka hunter-gatherers. We used portable remote-sensing devices to quantify the proportion of time children under the age of 4 spent in close proximity to different categories of potential allomother. Both related and unrelated, and reproductively active and inactive, campmates had substantial involvement in children's close-proximity networks. Unrelated campmates, siblings and subadults were the most involved in both populations, whereas the involvement of fathers and grandmothers was the most variable between the two populations. Finally, the involvement of sexually mature, reproductively inactive adults was low. Where possible, we compared our findings with studies of other hunter-gatherer societies, and observed numerous consistent trends. Based on our results we discuss why hunter-gatherer allomothering cannot be fully characterised as cooperative or communal breeding.</p>","PeriodicalId":36414,"journal":{"name":"Evolutionary Human Sciences","volume":"6 ","pages":"e11"},"PeriodicalIF":2.6,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10955362/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140185898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Sex ratios and gender norms: why both are needed to understand sexual conflict in humans.","authors":"Renée V Hagen, Brooke A Scelza","doi":"10.1017/ehs.2024.3","DOIUrl":"10.1017/ehs.2024.3","url":null,"abstract":"<p><p>Sexual conflict theory has been successfully applied to predict how in non-human animal populations, sex ratios can lead to conflicting reproductive interests of females and males and affect their bargaining positions in resolving such conflicts of interests. Recently this theory has been extended to understand the resolution of sexual conflict in humans, but with mixed success. We argue that an underappreciation of the complex relationship between gender norms and sex ratios has hampered a successful understanding of sexual conflict in humans. In this paper, we review and expand upon existing theory to increase its applicability to humans, where gender norms regulate sex ratio effects on sexual conflict. Gender norms constrain who is on the marriage market and how they are valued, and may affect reproductive decision-making power. Gender norms can also directly affect sex ratios, and we hypothesize that they structure how individuals respond to market value gained or lost through biased sex ratios. Importantly, gender norms are in part a product of women's and men's sometimes conflicting reproductive interests, but these norms are also subject to other evolutionary processes. An integration of sexual conflict theory and cultural evolutionary theory is required to allow for a full understanding of sexual conflict in humans.</p>","PeriodicalId":36414,"journal":{"name":"Evolutionary Human Sciences","volume":"6 ","pages":"e10"},"PeriodicalIF":2.6,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10897493/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139984106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Frederik Hartmann, Seán G. Roberts, Paul Valdes, Rebecca Grollemund
{"title":"Investigating environmental effects on phonology using diachronic models","authors":"Frederik Hartmann, Seán G. Roberts, Paul Valdes, Rebecca Grollemund","doi":"10.1017/ehs.2023.33","DOIUrl":"https://doi.org/10.1017/ehs.2023.33","url":null,"abstract":"\u0000 Previous work has proposed various mechanisms by which the environment may affect the emergence of linguistic features. For example, dry air may cause careful control of pitch to be more effortful, and so affect the emergence of linguistic distinctions that rely on pitch such as lexical tone or vowel inventories. Criticisms of these proposals point out that there are both historical and geographic confounds that need to be controlled for. We take a causal inference approach to this problem to design the most detailed test of the theory to date. We analyse languages from the Bantu language family, using prior geographic-phylogenetic tree of relationships to establish where and when languages were spoken. This is combined with estimates of humidity for those times and places, taken from historical climate models. We then estimate the strength of causal relationships in a causal path model, controlling for various influences of inheritance and borrowing. We find no evidence to support the previous claims that humidity affects the emergence of lexical tone. This study shows how using causal inference approaches lets us test complex causal claims about the cultural evolution of language.","PeriodicalId":36414,"journal":{"name":"Evolutionary Human Sciences","volume":"11 8","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139451073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}