141 research outputs found
Socialization, autonomy, and cooperation: Insights from task assignment among the egalitarian BaYaka
Hunter-gatherer childrenâs object play and tool use: An ethnohistorical analysis
Learning to use, make, and modify tools is key to our speciesâ success. Researchers have hypothesized that play with objects may have a foundational role in the ontogeny of tool use and, over evolutionary timescales, in cumulative technological innovation. Yet, there are few systematic studies investigating childrenâs interactions with objects outside the post-industrialized West. Here, we survey the ethnohistorical record to uncover cross-cultural trends regarding hunter-gatherer childrenâs use of objects during play and instrumental activities. Our dataset, consisting of 434 observations of childrenâs toys and tools from 54 hunter-gatherer societies, reveals several salient trends: Most objects in our dataset are used in play. Children readily manufacture their own toys, such as dolls and shelters. Most of the objects that children interact with are constructed from multiple materials. Most of the objects in our dataset are full-sized or miniature versions of adult tools, reflecting learning for adult roles. Children also engage with objects related to child culture, primarily during play. Taken together, our findings show that hunter-gatherer children grow up playing, making, and learning with objects
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Bayaka adolescent boys nominate accessible adult men as preferred spear hunting = models les adolescents bayaka nomment les hommes adultes qui leurs sont accessibles comme modĂšles prĂ©fĂ©rĂ©s pour lâapprentissage de la chasse Ă la lance
Data availability: data are available on request. The code used in the analysis can be found online at https://www.journals.uchicago.edu/doi/suppl/10.1086/716853/suppl_file/303893code.zip .Online enhancements: appendix, R code.Humans are selective social learners. In a cultural landscape with many potential models, learners must balance the cost associated with learning from successful models with learning from accessible ones. Using structured interviews, we investigate the model selection biases of Congolese BaYaka adolescent boys learning to hunt with spears (n = 24; mean age [mage] = 15.79 years; range, 12â20 years). Results from social relations models suggest that adolescents nominated accessible adult men (closely related kin and neighbors) as preferred spear hunting models. Direct cues for success were not strong predictors for adolescent nomination in the statistical models, despite learners justifying model selection according to teaching and spear hunting skill. Indirect cues including body mass index, age, and cross-domain prestige were weak predictors for adolescent nomination. We interpret these findings as suggesting that BaYaka spear hunting knowledge is widely shared in the community, with all adult men participating in spear hunting and therefore having the requisite experience to transmit this skill. This supports previous findings that in egalitarian societies with low rates of role specialization, prestige has limited importance for cross-domain learning.
Les ĂȘtres humains sont des apprenants sociaux sĂ©lectifs. Dans un paysage culturel comportant de nombreux modĂšles potentiels, les apprenants doivent trouver un Ă©quilibre entre le coĂ»t associĂ© Ă lâapprentissage Ă partir de modĂšles qui ont fait leurs preuves et celui Ă partir de modĂšles accessibles. Ă lâaide dâentretiens structurĂ©s, nous Ă©tudions les biais de sĂ©lection de modĂšles des adolescents congolais BaYaka qui apprennent Ă chasser Ă la lance (n = 24, Ăąge moyen = 15,79 ans, intervalle: 12â20 ans). Les rĂ©sultats des modĂšles de relations sociales suggĂšrent que les adolescents dĂ©signent des hommes adultes accessibles (parents proches et voisins) comme modĂšles prĂ©fĂ©rĂ©s de chasse Ă la lance. Les indices directs de rĂ©ussite ne constituaient pas des prĂ©dicteurs forts de nomination par des adolescents dans les modĂšles statistiques, bien que les apprenants justifiaient la sĂ©lection du modĂšle en fonction des habiletĂ©s dâenseignement et de la chasse Ă la lance. Les indices indirects, dont lâindice de masse corporelle, lâĂąge et le prestige inter-domaines, constituaient de faibles prĂ©dicteurs de la nomination par les adolescents. Ces rĂ©sultats suggĂšrent que la connaissance de la chasse Ă la lance des BaYaka est largement partagĂ©e dans la communautĂ©, puisque tous les hommes adultes participent Ă la chasse Ă la lance et ont donc lâexpĂ©rience requise pour transmettre cette compĂ©tence. Ceci confirme les rĂ©sultats de recherches antĂ©rieures selon lesquels dans les sociĂ©tĂ©s Ă©galitaires, qui ont de faibles niveaux de spĂ©cialisation des rĂŽles, le prestige a une importance limitĂ©e dans lâapprentissage inter-domaines.Funding for this research was provided by awards from the Wenner-Gren Foundation (no. 9789) and the Leakey Foundation to S. Lew-Levy and A. Milks. Research was also supported by a Social Sciences and Humanities Research Council of Canada Postdoctoral Fellowship (no. 756-2019-0102) to S. Lew-Levy
Out of the empirical box: A mixed-methods study of tool innovation among Congolese BaYaka forager and Bondongo fisherâfarmer children
© 2021 The Authors. Tool innovation has played a crucial role in human adaptation. Yet, this capacity seems to arise late in development. Before 8 years of age, many children struggle to solve the hook task, a common measure of tool innovation that requires modification of a straight pipe cleaner into a hook to extract a prize. Whether these findings are generalizable beyond postindustrialized Western children remains unclear. In many small-scale subsistence societies, children engage in daily tool use and modification, experiences that theoretically could enhance innovative capabilities. Although two previous studies found no differences in innovative ability between children from Western and small-scale subsistence societies, these did not account for the latterâs inexperience with pipe cleaners. Thus, the current study investigated how familiarity with pipe cleaners affected hook task success in 132 Congolese BaYaka foragers (57 girls) and 59 Bondongo fisherâfarmers (23 girls) aged 4â12 years. We contextualized these findings within childrenâs interview responses and naturalistic observations of how pipe cleaners were incorporated into daily activities. Counter to our expectation, prior exposure did not improve childrenâs performance during the hook task. Bondongo children innovated significantly more hooks than BaYaka children, possibly because they participate in hook-and-line fishing. Observations and interviews showed that children imagined and innovated novel uses for pipe cleaners outside the experimental context, including headbands, bracelets, and suspenders. We relate our findings to ongoing debates regarding systematic versus unsystematic tool innovation, the importance of prior experience for the ontogeny of tool innovation, and the external validity of experimental paradigms
Mothers' and fathers' joint profiles for testosterone and oxytocin in a smallâscale fishingâfarming community: Variation based on marital conflict and paternal contributions
Introduction: Testosterone and oxytocin are psychobiological mechanisms that interrelate with relationship quality between parents and the quantity and quality of parenting behaviors, thereby affecting child outcomes. Their joint production based on family dynamics has rarely been tested, particularly crossâculturally. Methods: We explored family function and salivary testosterone and oxytocin in mothers and fathers in a smallâscale, fishingâfarming society in Republic of the Congo. Fathers ranked one another in three domains of family life pertaining to the local cultural model of fatherhood. Results: Fathers who were viewed as better providers had relatively lower oxytocin and higher testosterone than men seen as poorer providers, who had lower testosterone and higher oxytocin. Fathers also had higher testosterone and lower oxytocin in marriages with more conflict, while those who had less marital conflict had reduced testosterone and higher oxytocin. In contrast, mothers in conflicted marriages showed the opposite profiles of relatively lower testosterone and higher oxytocin. Mothers had higher oxytocin and lower testosterone if fathers were uninvolved as direct caregivers, while mothers showed an opposing pattern for the two hormones if fathers were seen as involved with direct care. Conclusions: These results shed new light on parents' dual oxytocin and testosterone profiles in a smallâscale society setting and highlight the flexibility of human parental psychobiology when fathers' roles and functions within families differ across cultures
A Systematic Mapping Approach of 16q12.2/FTO and BMI in More Than 20,000 African Americans Narrows in on the Underlying Functional Variation: Results from the Population Architecture using Genomics and Epidemiology (PAGE) Study
Genetic variants in intron 1 of the fat mass- and obesity-associated (FTO) gene have been consistently associated with body mass index (BMI) in Europeans. However, follow-up studies in African Americans (AA) have shown no support for some of the most consistently BMI-associated FTO index single nucleotide polymorphisms (SNPs). This is most likely explained by different race-specific linkage disequilibrium (LD) patterns and lower correlation overall in AA, which provides the opportunity to fine-map this region and narrow in on the functional variant. To comprehensively explore the 16q12.2/FTO locus and to search for second independent signals in the broader region, we fine-mapped a 646-kb region, encompassing the large FTO gene and the flanking gene RPGRIP1L by investigating a total of 3,756 variants (1,529 genotyped and 2,227 imputed variants) in 20,488 AAs across five studies. We observed associations between BMI and variants in the known FTO intron 1 locus: the SNP with the most significant p-value, rs56137030 (8.3Ă10-6) had not been highlighted in previous studies. While rs56137030was correlated at r2>0.5 with 103 SNPs in Europeans (including the GWAS index SNPs), this number was reduced to 28 SNPs in AA. Among rs56137030 and the 28 correlated SNPs, six were located within candidate intronic regulatory elements, including rs1421085, for which we predicted allele-specific binding affinity for the transcription factor CUX1, which has recently been implicated in the regulation of FTO. We did not find strong evidence for a second independent signal in the broader region. In summary, this large fine-mapping study in AA has substantially reduced the number of common alleles that are likely to be functional candidates of the known FTO locus. Importantly our study demonstrated that comprehensive fine-mapping in AA provides a powerful approach to narrow in on the functional candidate(s) underlying the initial GWAS findings in European populations
Womenâs subsistence strategies predict fertility across cultures, but context matters
While it is commonly assumed that farmers have higher, and foragers lower, fertility compared to populations practicing other forms of subsistence, robust supportive evidence is lacking. We tested whether subsistence activitiesâincorporating market integrationâare associated with fertility in 10,250 women from 27 small-scale societies and found considerable variation in fertility. This variation did not align with group-level subsistence typologies. Societies labeled as âfarmersâ did not have higher fertility than others, while âforagersâ did not have lower fertility. However, at the individual level, we found strong evidence that fertility was positively associated with farming and moderate evidence of a negative relationship between foraging and fertility. Markers of market integration were strongly negatively correlated with fertility. Despite strong cross-cultural evidence, these relationships were not consistent in all populations, highlighting the importance of the socioecological context, which likely influences the diverse mechanisms driving the relationship between fertility and subsistence
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Women's subsistence strategies predict fertility across cultures, but context matters
Data, Materials, and Software Availability. Anonymized CSV file data have been deposited in OSF (https://osf.io/8d9n2/?view_only=9e07c25 e06414f7a8d041e80e8539e5c) (49).Supporting Information is available online at: https://www.pnas.org/doi/suppl/10.1073/pnas.2318181121/suppl_file/pnas.2318181121.sapp.pdf .While it is commonly assumed that farmers have higher, and foragers lower, fertility compared to populations practicing other forms of subsistence, robust supportive evidence is lacking. We tested whether subsistence activitiesâincorporating market integrationâare associated with fertility in 10,250 women from 27 small-scale societies and found considerable variation in fertility. This variation did not align with group-level subsistence typologies. Societies labeled as âfarmersâ did not have higher fertility than others, while âforagersâ did not have lower fertility. However, at the individual level, we found strong evidence that fertility was positively associated with farming and moderate evidence of a negative relationship between foraging and fertility. Markers of market integration were strongly negatively correlated with fertility. Despite strong cross-cultural evidence, these relationships were not consistent in all populations, highlighting the importance of the socioecological context, which likely influences the diverse mechanisms driving the relationship between fertility and subsistence.A.E.P. received funding from the Medical Research Council MRC (grant no. MR/P014216/1). J.S. acknowledges Institute for Advanced Study in Toulouse funding from the French National Research Agency (ANR) under the Investments for the Future (Investissements dâAvenir) program, grant ANR-17-EURE-0010. This material is based upon work supported while S.M. served at the National Science Foundation (NSF)
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External ballistics of Pleistocene hand-thrown spears: experimental performance data and implications for human evolution
The appearance of weaponry - technology designed to kill - is a critical but poorly established threshold
in human evolution. It is an important behavioural marker representing evolutionary changes in
ecology, cognition, language and social behaviours. While the earliest weapons are often considered
to be hand-held and consequently short-ranged, the subsequent appearance of distance weapons is a
crucial development. Projectiles are seen as an improvement over contact weapons, and are considered
by some to have originated only with our own species in the Middle Stone Age and Upper Palaeolithic.
Despite the importance of distance weapons in the emergence of full behavioral modernity, systematic
experimentation using trained throwers to evaluate the ballistics of thrown spears during fight and at
impact is lacking. This paper addresses this by presenting results from a trial of trained javelin athletes,
providing new estimates for key performance parameters. Overlaps in distances and impact energies
between hand-thrown spears and spearthrowers are evidenced, and skill emerges as a signifcant factor in
successful use. The results show that distance hunting was likely within the repertoire of hunting strategies
of Neanderthals, and the resulting behavioural flexibility closely mirrors that of our own specie
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