Human Nature-An Interdisciplinary Biosocial Perspective最新文献

Previous research indicates that having children can negatively affect relationship satisfaction, yet it may also strengthen bonding between partners. Romantic love is hypothesized to serve as a commitment device contributing to marital satisfaction. Interestingly, the relationship between romantic love and the number of children is complex and has received limited empirical attention, especially in diverse cultural contexts. However, some evidence from traditional societies suggests a positive correlation. Guided by Sternberg's Triangular Theory of Love, we examined the relationship between the number of children and romantic love and its three components (passion, intimacy, commitment) across 25 populations. Based on prior research, we hypothesized that the number of children would be positively associated with passion and commitment but negatively associated with intimacy. Our global sample included 3,187 married or engaged individuals (55.9% women), aged 18-99 years (M = 38.69, SD = 10.55), from 25 countries. Contrary to our predictions, having children, but not the number of children, was negatively related to overall romantic love, intimacy, and passion, but unrelated to commitment. These findings suggest that parenthood may be linked to reduced romantic love, particularly in terms of intimacy and passion, across diverse cultural settings. This pattern may reflect challenges commonly associated with the transition to parenthood, including increased stress, fatigue, financial strain, and work-life conflict, which can diminish partners' sense of closeness and attraction. Overall, the results underscore the importance of supporting couples' romantic relationships during the parenting stage to help sustain emotional and physical connection under the demands of family life.

Bride kidnapping, where Women are abducted for marriage, persists in Kyrgyzstan despite being illegal. Although it is estimated that up to one-third of marriages in Kyrgyzstan result from abduction, the true prevalence of this practice is unknown. Estimates are based on self-reporting of a practice that has become illegal. Here we examine whether there are sex and intergenerational differences in this reporting, that reflect a changing legal and social environment that might influence the self-reporting of bride kidnapping marriage. Using data from 468 participants in two Kyrgyz villages collected through 2023, this study examines self-reporting discrepancies in kidnap marriages among married couples. Significant differences were found in how husbands and wives report their marriages: husbands often describe the marriages as consensual, while wives see them as non-consensual. These discrepancies show a convergence over time, with couples married more recently agreeing on the marriage type. Furthermore, fathers often reported their son's marriages as consensual, while the sons themselves reported them as non-consensual, highlighting a generational divide. Our findings suggest a normative transformation driven by cohort replacement, where evolving attitudes toward consent erode the cultural mechanisms sustaining bride kidnapping. This offers insight into the evolutionary dynamics of such gender-biased harmful practices, highlighting how legal reforms and societal pressures reshape perceptions over time.

Social dilemmas in the real world, such as pollution and the extraction of resources, often differ regarding the visibility of involved actors and their behavior. While publicly disclosing individual decisions in social dilemmas is known to increase cooperation, little is known about whether revealing individual identities specifically makes a difference. This study uses an artefactual public good field experiment conducted in rural Namibia with 144 villagers, who are randomly assigned to one of two experimental conditions: one in which group members' identities are not disclosed and one in which they are. Individual contributions to the public good remain private in both cases, so the only difference lies in whether participants can see who their group members are. In addition, the experiment's setting in village communities entails pre-existing social ties between participants, which likely amplify potential effects that revealing identities can have on cooperation and allow investigating the role of group composition, such as the share of friends and family members. Results, somewhat unexpectedly, show that contributions to the public good are significantly higher when group members cannot identify one another - a finding that can be explained by several, not necessarily mutually exclusive, mechanisms. Exploratory analyses further reveal that contributions in the identified condition are distinctly lower when group members are socially distant from each other. Although overall variability of contributions does not differ across the two experimental conditions, decisions are more homogenous within groups and more heterogeneous between groups when identities are disclosed.

The evolution of menopause, grandmothering and long lifespan represent key events in the evolution of human life history. Demographic studies have amply demonstated inclusive fitness benefits from grandmaternal care, but the hormonal bases of such care, and how it evolved in relation to other reproductive and demographic traits, have yet to be addressed in detail. We propose and evaluate a novel hypothesis for the coevolution and adaptive covariation of life history, physiology, and behavior among women in this context. The hypothesis centers on relatively low testosterone, which promotes: (1) earlier, higher fertility and fecundity, (2) earlier cessation of ovarian activity (leading to earlier grandmothering), and (3) enhanced alloparental care. The hypothesis can help to explain among-female variation in grandmaternal care, and potential trajectories for the concerted evolution of grandmothering, prolonged human lifespan, and associated life history traits. A suite of convergent evidence supports the hypothesis, and it makes new predictions that are straightforward to test.

Compared to other apes, humans show a distinctive capacity for the cultural learning and transmission of know-how: we extract know-how from other individuals and artifacts in ways that regularly give rise to forms of know-how that no single individual could realistically invent on their own. Such a capacity is plausibly foundational to humans' striking cultural prowess and hence all that goes with it (e.g., symbolic language, religion). In this article, we critically examine attempts to date the transformation of know-how copying in the hominin lineage through an estimation of the costs of stone toolmaking. More specifically, we take as our target the idea that the costs inherent in making early stone tools, that is, Oldowan and Early Acheulean tools, already likely reflect a meaingful upgrade in hominin know-how copying abilities. Our survey of potentially relevant costs of stone toolmaking is generous, covering: (i) the risks and dangers of toolmaking; (ii) the time, energy, and opportunity costs of toolmaking; and finally (iii) the material costs of toolmaking. Ultimately, we find that, based on current evidence pertaining to these costs, the case for inferring know-how copying abilities in Oldowan or even Early Acheulean stone toolmakers is weak. This skeptical conclusion, combined with independent evidence that the design of stone tools during this period likely remained within the range of what the relevant hominins could invent without know-how copying, points to a later date for the establishment of this crucial human skill.

The self-domestication hypothesis has made significant contributions to our thinking about hominin evolution and ecology. It has struggled, however, to find compelling and testable causes of reductions in hominin aggression and violent behavior. This paper examines variability among hominin mating systems and imbalances in operation sex ratios (OSRs) as a potential factor influencing levels of aggression resulting from male intrasexual competition, i.e., male-male competitive aggression. This paper uses multivariate generalized linear modeling (GLM) to examine data from modern hunter-gatherer societies having to do with the causes and consequences of OSR imbalances (as reflected by levels of polygamy) and male intrasexual competition. This paper focuses especially on the role of population density as a potential source of OSR variability. This paper shows that population density correlates strongly with hunter-gatherer OSRs and that this relationship remains strong when controlling for the effects of other potentially intercorrelated variables. This paper shows that, among modern hunter-gatherers, lower population densities lead to greater imbalances in terms of OSRs and therefore higher levels of male-male aggression. This implies high levels of male intrasexual competition among early hominins given likely conditions of very low population densities. The paper closes by proposing some strategies for investigating hominin demographic patterning prehistorically and predicting OSR imbalances, as well as intrasexual competition, based on that information.

In four pre-registered studies, we tested implications from a cooperation model that explains victim-blaming and victim-devaluation as the result of cooperation dilemmas, as a way for people to avoid the costs of helping victims (who seem to be unpromising cooperation partners) without paying the reputational cost of being seen as ungenerous, reluctant cooperators. An implication of this perspective is that, if a victim of misfortune is seen as imposing costs on others by requesting help (as opposed to bearing the costs), they will be seen as persons of low character, avoided as future cooperators, and deemed responsible for their misfortune (seen as negligent). The four studies presented here support these predictions. The effect is not confounded by familiar or social obligations, as it occurs in the same way when the targets, from whom help is requested, are the victim's parents, siblings, best friends or communities. Contrary to expectations, negligence attributions were not modulated by the victim's being described as poor (in need of help) or rich (not in need).

Previous work has suggested that males and females adopt different exploration styles, with females often taking a more secure, or cautious exploration approach. However, exploration behavior is multi-faceted, and previous studies often investigated only specific aspects of it. As a result, sex differences in exploration remain vaguely defined, and it currently remains unclear when differences develop. In the current study, females (n = 206) and males (n = 218) aged 7-77 years explored a 3D virtual environment. First, we computed a series of exploration measures that are commonly used in the animal literature (including roaming entropy, distance traveled, shape of exploration and exploratory efficiency). Taking a fine-grained approach, based on a hierarchical cluster analysis we identified three distinct measures of exploration: (1) Exploratory activity; (2) Exploratory efficiency; (3) Shape of exploration. We investigated whether these distinct aspects capture individual differences- between sexes and across the lifespan- in exploration behavior. Males were found to explore more than females, as evidenced by higher exploratory activity and a more complex shape of exploration. Interestingly, however, females explored more efficiently than males. No interaction between age and sex was observed, suggesting that the effect remains stable across the lifespan. These findings suggest that even though women show more caution when exploring an unknown environment, they are more efficient in charting it. Our novel fine-grained exploratory behavior analyses further suggested that older individuals had a simpler exploration shape- as defined by lower sinuosity/tortuosity in their path- than younger individuals, while other exploration measures were not affected by age. The current novel findings thus suggest that specific characteristics of exploration behavior depend on individual differences, including sex and age. Previous work has suggested that exploration behavior is affected in several neuropsychiatric disorders (e.g., in schizophrenia), and our measures of exploration could potentially be used to characterize unique aspects of these disorders, and serve as cognitive markers.

To gain support, children use signals to communicate their needs and wants to parents. Infant signals of need, particularly infant cries, have been extensively studied in diverse populations. However, the full range of potential child signals of need, which extend beyond cries, has rarely been investigated in a single study of children of all ages. To help fill this gap, we collected mother and other primary caregiver reports of three common types of child signaling from 131 families with 263 children on Utila, a small island off the coast of Honduras. In exploratory analyses, we found that child signaling was common in both sexes and across all ages, although it decreased with age and neighborhood quality and increased with the frequency of conflict between children and caretakers. Consistent with signaling theory, children who were sad more frequently were perceived as needier within the household and were more likely to receive investment. Caregivers were less likely to respond positively in situations of family conflict or child transgressions, and more likely for injuries and illness. Our results suggest that evolutionary theories of signaling can help explain patterns of child sadness, crying, and temper tantrums.