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In this article, we integrate cultural evolutionary theory with empirical research from developmental psychology, cultural anthropology, and primatology to explore the role of peer learning in the development of complex instrumental skills and behavioral norms. We show that instrumental imitation, contingent teaching, generative collaboration, and selective copying contribute to domain-specific transmission of knowledge between peers. Stages of development and characteristics inherent to the learner and model influence how and when children learn from each other. Peer learning is persistent across societies despite cultural beliefs that favor adult-child transmission in some settings. Comparative research hints at the possibility that children's greater motivation to interact with and learn from each other may set humans apart from other primates. We conclude by outlining avenues for future research, including how individual characteristics and developmental changes in social networks, motivation, and cognition may contribute to cultural evolution.

Importance: Although prolonged fasting has become increasingly popular, the favourable biological adaptations and possible adverse effects in humans have yet to be fully elucidated. Objective: To investigate the effects of a three-day water-only fasting, with or without exercise-induced glycogen depletion, on autophagy activation and the molecular pathways involved in cellular damage accumulation and repair in healthy humans. Design: A randomised, single-centre, two-period, two-sequence crossover trial. The primary outcome is autophagic activity, assessed as flux in peripheral blood mononuclear cells (PBMCs) measured in the context of whole blood. Secondary outcomes include changes in body composition, heart rate variability, endothelial function, and genomic, epigenomic, metabolomic, proteomic, and metagenomic adaptations to fasting in plasma, platelets, urine, stools, and PBMCs. Detailed profiling of circulating immune cell populations and their functional states will be assessed by flow cytometry. Setting: All clinical investigations will be undertaken at the Charles Perkins Centre Royal Prince Alfred Hospital clinic, University of Sydney, Australia. Participants: Twenty-four individuals aged 18 to 70 years, with a BMI of 20–40 kg/m2, free of major health conditions other than obesity. Discussion: While autophagic flux induction through fasting has garnered interest, there is a notable lack of human studies on this topic. This trial aims to provide the most detailed and integrated analysis of how three days of prolonged water-only fasting, combined with glycogen-depleting exercise, affects autophagy activation and other crucial metabolic and molecular pathways linked to cellular, metabolic, and immune health. Insights from this study may pave the way for safe and effective strategies to induce autophagy, offering potential preventive interventions for a range of chronic conditions. [ABSTRACT FROM AUTHOR]

This study tested the prediction that, with age, children should rely less on familiarity and more on expertise in their selective social learning. Experiment 1 (N = 50) found that 5- to 6-year-olds copied the technique their mother used to extract a prize from a novel puzzle box, in preference to both a stranger and an established expert. This bias occurred despite children acknowledging the expert model's superior capability. Experiment 2 (N = 50) demonstrated a shift in 7- to 8-year-olds toward copying the expert. Children aged 9-10 years did not copy according to a model bias. The findings of a follow-up study (N = 30) confirmed that, instead, they prioritized their own--partially flawed--causal understanding of the puzzle box.

The current study investigated children's solution choice and imitation of causally-irrelevant actions by using a controlled design to mirror naturalistic learning contexts in which children receive social information for tasks about which they have some degree of prior knowledge. Five-year-old children (N = 167) were presented with a reward retrieval task and either given a social demonstration of a solution or no information, thus potentially acquiring a solution through personal exploration. Fifty-three children who acquired a solution either socially or asocially were then presented with an alternative solution that included irrelevant actions. Rather than remaining polarised to their initial solution like non-human animals, these children attempted the newly presented solution, incorporating both solutions into their repertoire. Such an adaptive and flexible learning strategy could increase task knowledge, provide generalizable knowledge in our tool-abundant culture and facilitate cumulative culture. Furthermore, children who acquired a solution through personally acquired information omitted subsequently demonstrated irrelevant actions to a greater extent than did children with prior social information. However, as some children with successful personally acquired information did copy the demonstrated irrelevant actions, we suggest that copying irrelevant actions may be influenced by social and causal cognition, resulting in an effective strategy which may facilitate acquisition of cultural norms when used discerningly. (Contains 2 tables and 2 figures.)

Pervasive gender gaps in academic subject and career choices are likely to be underpinned by social influences, including gender stereotypes of competence in academic and career domains (e.g., men excel at engineering, women excel at care), and model-based social learning biases (i.e., selective copying of particular individuals). Here, we explore the influence of gender stereotypes on social learning decisions in adolescent and adult males and females. Participants (Exp 1: N = 69 adolescents; Exp 2: N = 265 adults) were presented with 16 difficult multiple-choice questions from stereotypically feminine (e.g., care) and masculine (e.g., engineering) domains. The answer choices included the correct response and three incorrect responses paired with a male model, a female model, or no model. Participants' gender stereotype knowledge and endorsement were measured, and adolescents (Exp. 1) listed their academic subject choices. As predicted, there was a bias towards copying answers paired with a model (Exp.1: 74%, Exp. 2: 65% ps <.001). This resulted in less success than would be expected by chance (Exp. 1: 12%, Exp. 2: 16% ps <.001), demonstrating a negative consequence of social information. Adults (Exp 2) showed gender stereotyped social learning biases; they were more likely to copy a male model in masculine questions and a female model in feminine questions (p =.012). However, adolescents (Exp 1) showed no evidence of this stereotype bias; rather, there was a tendency for male adolescents to copy male models regardless of domain (p =.004). This own-gender bias was not apparent in female adolescents. In Exp 1, endorsement of masculine stereotypes was positively associated with selecting more own-gender typical academic subjects at school and copying significantly more male models in the male questions. The current study provides evidence for the first time that decision-making in both adolescence and adulthood is impacted by gender biases. [ABSTRACT FROM AUTHOR]

In the first of two experiments, we demonstrate the spread of a novel form of tool use across 20 "cultural generations" of child-to-child transmission. An experimentally seeded technique spread with 100% fidelity along twice as many "generations" as has been investigated in recent exploratory "diffusion" experiments of this type. This contrasted with only a single child discovering the technique spontaneously in a comparable group tested individually without any model. This study accordingly documents children's social learning of tool use on a new, population-level scale that characterizes real-world cultural phenomena. In a second experiment, underlying social learning processes were investigated with a focus on the contrast between imitation (defined as copying actions) and emulation (defined as learning from the results of actions only). In two different "ghost" conditions, children were presented with the task used in the first experiment but now operated without sight of an agent performing the task, thereby presenting only the information used in emulation. Children in ghost conditions were less successful than those who had watched a model in action and showed variable matching to what they had seen. These findings suggest the importance of observational learning of complex tool use through imitation rather than only through emulation. Results of the two experiments are compared with those of similar experiments conducted previously with chimpanzees and are discussed in relation to the wider perspective of human culture and the influence of task complexity on social learning. (Contains 1 table and 2 figures.)

Across two studies, we investigated gender stereotype knowledge and endorsement in UK schoolchildren, and their impact on academic subject choice. In Study 1, children aged 9–11 (N = 68) and 13–15 (N = 61) completed a newly developed Gender Attribute scale assessing their knowledge and endorsement of gender stereotypes relating to academic subjects and occupations. Participants demonstrated gender stereotype knowledge and endorsement, although significantly higher knowledge than endorsement scores indicated a level of stereotype rejection. Stereotype knowledge was greater in the older age group, and older girls showed significantly higher levels of stereotype rejection than all other groups. In Study 2, children aged 13–15 (N = 165) completed the Gender Attribute scale and provided information on their school subject choices. Patterns of stereotype knowledge and endorsement followed those of Study 1. Subject choice information showed that boys selected significantly more masculine than feminine subjects, while girls chose a similar proportion of each. Further, boys' level of gender stereotype endorsement predicted their subject choices, while girls' did not. We suggest that in contemporary UK some progress is being made in relation to girls challenging stereotypes that work against them but that more work is needed to encourage boys into female‐dominated disciplines. [ABSTRACT FROM AUTHOR]

Romantic relationships are an important part of human life and thus, according to the continuity hypothesis of dreaming, one's romantic partner should show up in dreams quite frequently. The present study is based on 1612 dream reports provided by 425 students. The findings confirmed the hypothesis that partner dreams are more frequent than ex-partner dreams and, thus, support the continuity hypothesis of dreaming. Moreover, interactions with ex-partners within the dream were more often negatively toned compared to dreamed interactions with the partner. Unexpectedly, we also found more positive emotions and friendliness in ex-partner dreams compared to partner dreams, indicating that partner dreams are more mundane. To conclude, dreams reflect important aspects of romantic partnerships and their break-ups and, thus, can be very helpful in psychotherapy. [ABSTRACT FROM AUTHOR]

When drawing faces, people show a systematic bias of placing the eyes higher up the head than they are placed in reality. This study investigated the development of this phenomenon while removing the potential confound of drawing ability. Participants (N = 124) in three age groups (3–5 yo, 10–11 yo, and adults) reconstructed two foam faces: one from observation and one from memory. The high eye placement bias was remarkably robust with mean eye placement in every condition significantly higher than the original faces. The same bias was not shown for mouth placement. Eye placement was highest for the youngest participants and for the memory conditions. The results suggest that an eye placement bias is not caused by the motor skill demands required for drawing and lend evidence to the suggestion that an eye placement bias is caused by perceptual and decision-making processes. [ABSTRACT FROM AUTHOR]

It has been claimed that a unique feature of human culture is that it accumulates beneficial modifications over time. On the basis of a couple of methodological considerations, we here argue that, perhaps surprisingly, there is insufficient evidence for a proper test of this claim. And we indicate what further research would be needed to firmly establish the cumulativeness of human culture. [ABSTRACT FROM AUTHOR]

Understanding individual differences in captive squirrel monkeys is a topic of importance both for improving welfare by catering to individual needs, and for better understanding the results and implications of behavioral research. In this study, 23 squirrel monkeys ( Saimiri sciureus), housed in an environment that is both a zoo enclosure and research facility, were assessed for (i) the time they spent by an observation window under three visitor conditions: no visitors, small groups, and large groups; (ii) their likelihood of participating in voluntary research; and (iii) zookeepers, ratings of personality. A Friedman's ANOVA and Wilcoxon post-hoc tests comparing mean times found that the monkeys spent more time by the window when there were large groups present than when there were small groups or no visitors. Thus, visitors do not seem to have a negative effect and may be enriching for certain individuals. Through GLMM and correlational analyses, it was found that high scores on the personality trait of playfulness and low scores on cautiousness, depression, and solitude were significant predictors of increased window approach behavior when visitors were present. The GLMM and correlational analyses assessing the links between personality traits and research participation found that low scores of cautiousness and high scores of playfulness, gentleness, affection, and friendliness, were significant predictors. The implications of these results are discussed in relation to selection bias and its potential confounding effect on cognitive studies with voluntary participation. [ABSTRACT FROM AUTHOR]

Cumulative culture is rare, if not altogether absent in nonhuman species. At the foundation of cumulative learning is the ability to modify, relinquish, or build upon previous behaviors flexibly to make them more productive or efficient. Within the primate literature, a failure to optimize solutions in this way is often proposed to derive from low-fidelity copying of witnessed behaviors, suboptimal social learning heuristics, or a lack of relevant sociocognitive adaptations. However, humans can also be markedly inflexible in their behaviors, perseverating with, or becoming fixated on, outdated or inappropriate responses. Humans show differential patterns of flexibility as a function of cognitive load, exhibiting difficulties with inhibiting suboptimal behaviors when there are high demands on working memory. We present a series of studies on captive chimpanzees that indicate that behavioral conservatism in apes may be underlain by similar constraints: Chimpanzees showed relatively little conservatism when behavioral optimization involved the inhibition of a well-established but simple solution, or the addition of a simple modification to a well-established but complex solution. In contrast, when behavioral optimization involved the inhibition of a well-established but complex solution, chimpanzees showed evidence of conservatism. We propose that conservatism is linked to behavioral complexity, potentially mediated by cognitive resource availability, and may be an important factor in the evolution of cumulative culture. [ABSTRACT FROM AUTHOR]