Human Nature-An Interdisciplinary Biosocial Perspective最新文献

This paper examines how innovative skills and knowledge are transmitted and acquired among adolescents in two hunter-gatherer communities, the Aka of southern Central African Republic and the Chabu of southwestern Ethiopia. Modes of transmission and processes of social learning are addressed. Innovation as well as social learning have been hypothesized to be key features of human cumulative culture, enhancing the fitness and survival of individuals in diverse environments. The innovation literature indicates adult males are more innovative than children and female adults and therefore predicts that adolescents will seek out adult males. Further, the mode of transmission should be oblique (i.e., learning from adults other than parents). Thus, learning of innovations should be oblique or horizontal rather than vertical, with adolescents paying particular attention to "successful" innovative individuals (prestige bias). The social learning literature indicates that complex skills or knowledge is likely to be learned through teaching, and therefore that teaching will be an important process in the transmission of innovations. In-depth and semi-structured interviews, informal observations, and systematic free-listing were used to evaluate these hypotheses. The study found that (1) cultural context patterned whether or not adolescents sought out adult male or female innovators; (2) oblique modes of transmission were mentioned with greater frequency than horizontal or vertical modes; (3) knowledge and skill bias was notable and explicitly linked by the adolescents to reproductive effort; and (4) teaching was biased toward same-sex individuals and was an important but not an exclusive means of transmitting complex skills and social knowledge.

Aspects of human life history and cognition, such as our long childhoods and extensive use of teaching, theoretically evolved to facilitate the acquisition of complex tasks. The present paper empirically examines the relationship between subsistence task difficulty and age of acquisition, rates of teaching, and rates of oblique transmission among Hadza and BaYaka foragers from Tanzania and the Republic of Congo. We further examine cross-cultural variation in how and from whom learning occurred. Learning patterns and community perceptions of task difficulty were assessed through interviews. We found no relationship between task difficulty, age of acquisition, and oblique transmission, and a weak but positive relationship between task difficulty and rates of teaching. While same-sex transmission was normative in both societies, tasks ranked as more difficult were more likely to be transmitted by men among the BaYaka, but not among the Hadza, potentially reflecting cross-cultural differences in the sexual division of subsistence and teaching labor. Further, the BaYaka were more likely to report learning via teaching, and less likely to report learning via observation, than the Hadza, possibly owing to differences in socialization practices.

Teaching is hypothesized to be a species-typical behavior in humans that contributed to the emergence of cumulative culture. Several within-culture studies indicate that foragers depend heavily on social learning to acquire practical skills and knowledge, but it is unknown whether teaching is universal across forager populations. Teaching can be defined ethologically as the modification of behavior by an expert in the presence of a novice, such that the expert incurs a cost and the novice acquires skills/knowledge more efficiently or that it would not acquire otherwise. One behavioral modification hypothesized to be an adaptation for teaching is ostensive communication-exaggerations of prosody and gesture that signal intent to transmit generalizable knowledge and indicate the intended receiver. On this view, the use of ostensive communication in conjunction with the transmission of generalizable knowledge constitutes evidence of teaching. Oral storytelling appears to meet these criteria: Indigenous peoples regard their traditions as important sources of ecological and social knowledge, and oral storytelling is widely reported to employ paralinguistic communication. To test this hypothesis, descriptions of performed narrative in forager societies were coded for the use of 14 ostensive-communicative behaviors and the presence of generalizable knowledge. Although biased toward North America, the study sample comprised 53 forager cultures spanning five continents, 34 language families, and diverse biomes. All cultures evinced the predicted behaviors. Results suggest that foragers use storytelling as a mode of instruction, thus providing cross-cultural evidence of teaching in forager populations.

A fundamental cognitive function found across a wide range of species and necessary for survival is the ability to navigate complex environments. It has been suggested that mobility may play an important role in the development of spatial skills. Despite evolutionary arguments offering logical explanations for why sex/gender differences in spatial abilities and mobility might exist, thus far there has been limited sampling from nonindustrialized and subsistence-based societies. This lack of sampling diversity has left many unanswered questions regarding the effects that environmental variation and cultural norms may have in shaping mobility patterns during childhood and the development of spatial competencies that may be associated with it. Here we examine variation in mobility (through GPS tracking and interviews), performance on large-scale spatial skills (i.e., navigational ability), and performance on small-scale spatial skills (e.g., mental rotation task, Corsi blocks task, and water-level task) among Twa forager/pastoralist children whose daily lives have been dramatically altered since settlement and the introduction of government-funded boarding schools. Unlike in previous findings among Twa adults, boys and girls (N = 88; aged 6-18) show similar patterns of travel on all measures of mobility. We also find no significant differences in spatial task performance by gender for large- or small-scale spatial skills. Further, children performed as well as adults did on mental rotation, and they outperformed adults on the water-level task. We discuss how children's early learning environments may influence the development of both large- and small-scale spatial skills.

We investigate whether age profiles of ethnobiological knowledge development are consistent with predictions derived from life history theory about the timing of productivity and reproduction. Life history models predict complementary knowledge profiles developing across the lifespan for women and men as they experience changes in embodied capital and the needs of dependent offspring. We evaluate these predictions using an ethnobiological knowledge assessment tool developed for an off-grid pastoralist population known as Choyeros, from Baja California Sur, Mexico. Our results indicate that while individuals acquire knowledge of most dangerous items and edible resources by early adulthood, knowledge of plants and animals relevant to the age and sex divided labor domains and ecologies (e.g., women's house gardens, men's herding activities in the wilderness) continues to develop into middle adulthood but to different degrees and at different rates for men and women. As the demands of offspring on parents accumulate with age, reproductive-aged adults continue to develop their knowledge to meet their children's needs. After controlling for vision, our analysis indicates that many post-reproductive adults show the greatest ethnobiological knowledge. These findings extend our understanding of the evolved human life history by illustrating how changes in embodied capital and the needs of dependent offspring predict the development of men's and women's ethnobiological knowledge across the lifespan.

Recent work with infants suggests that plant foraging throughout evolutionary history has shaped the design of the human mind. Infants in Germany and the US avoid touching plants and engage in more social looking toward adults before touching them. This combination of behavioral avoidance and social looking strategies enables safe and rapid social learning about plant properties within the first two years of life. Here, we explore how growing up in a context that requires frequent interaction with plants shapes children's responses with the participation of communities in rural Fiji. We conducted two interviews with adults and a behavioral study with children. The adult interviews map the plant learning landscape in these communities and provide context for the child study. The child study used a time-to-touch paradigm to examine whether 6- to 48-month-olds (N = 33) in participating communities exhibit avoidance behaviors and social looking patterns that are similar to, or different from, those of German and American infants. Our adult interview results confirmed that knowledge about daily and medicinal uses of plants is widely known throughout the communities, and children are given many opportunities to informally learn about plants. The results of the child behavioral study suggest that young Fijian children, like German and American infants, are reluctant to reach for novel artificial plants and are fastest to interact with familiar household items and shells. In contrast to German and American infants, Fijian children also quickly reached for familiar real plants and did not engage in differential social looking before touching them. These results suggest that cultural contexts flexibly shape the development of plant-relevant cognitive design.

Previous work proposes that dispositional fear exists predominantly among political conservatives, generating the appearance that fears align strictly along party lines. This view obscures evolutionary dynamics because fear evolved to protect against myriad threats, not merely those in the political realm. We suggest prior work in this area has been biased by selection on the dependent variable, resulting from an examination of exclusively politically oriented fears that privilege conservative values. Because the adaptation regulating fear should be based upon both universal and ancestral-specific selection pressures combined with developmental and individual differences, the elicitation of it should prove variable across the ideological continuum dependent upon specific combinations of fear and value domains. In a sample of ~ 1,600 Australians assessed with a subset of the Fear Survey Schedule II, we find fears not infused with political content are differentially influential across the political spectrum. Specifically, those who are more fearful of sharp objects, graveyards, and urinating in public are more socially conservative and less supportive of gay rights. Those who are more fearful of death are more supportive of gay rights. Those who are more fearful of suffocating and swimming alone are more concerned about emissions controls and immigration, while those who are more fearful of thunderstorms are also more anti-immigration. Contrary to existing research, both liberals and conservatives are more fearful of different circumstances, and the role of dispositional fears are attitude-specific.

How does segregation along ethnic boundaries emerge in social networks? Human evolution resulted in highly social beings, capable of prosociality, mindreading, and self-control, which are important aspects of the "social brain." Our neurophysiologically "wired" social cognition implies different cognitive goal frames. In line with recent developments in behavioral theory, the present study defines network ties as episodes of social exchange. This dynamic definition can account for shifts in goal frames during an exchange episode: whereas deliberate choice and hedonic or gain goals drive the initiation of a tie, given the opportunity structure, the normative goal frame activates a strong dynamic effect of reciprocity, which limits actors' choice set and appears as "self-organization" at the network level. Longitudinal analyses of 18 birthday party networks comprising 501 students support the definition of network ties as exchange episodes, as well as the relevance of humans' inherent tendency to reciprocate. However, reciprocation is much stronger in dyads of the same ethnicity than in dyads of different ethnicities. Network segregation along ethnic boundaries results from deliberate decisions during the initiation of an episode, but also from different commitments to reciprocity during the ongoing exchange process, depending on intra or interethnic dyadic constellations.

Two prominent theoretical frameworks in moral psychology, Moral Foundations and Dual Process Theory, share a broad foundational assumption that individual differences in human morality are dispositional and in part due to genetic variation. The only published direct test of heritability, however, found little evidence of genetic influences on moral judgments using instrumentation approaches associated with Moral Foundations Theory. This raised questions about one of the core assumptions underpinning intuitionist theories of moral psychology. Here we examine the heritability of moral psychology using the moral dilemmas approach commonly used in Dual Process Theory research. Using such measures, we find consistent and significant evidence of heritability. These findings have important implications not only for understanding which measures do, or do not, tap into the genetically influenced aspects of moral decision-making, but in better establishing the utility and validity of different intuitionist theoretical frameworks and the source of why people differ in those frameworks.