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Testing the Trivers-Willard Hypothesis on Polish kings and dukes. ANTHROPOLOGICAL REVIEW 2019. [DOI: 10.2478/anre-2019-0030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The Trivers-Willard Hypothesis (TWH), frequently investigated by evolutionary psychologists, states that human beings may have evolved to produce a greater number of sons when having a high status, and a greater number of daughters when having a low status. To test this hypothesis, we examined the sex of children of Polish high status: kings, dukes, magnates families; and of low status: peasants, burghers and gentry. Our findings do not provide evidence for the Trivers-Willard Hypothesis (TWH), as there were no differences between offspring’s sex ratio among any of the investigated social classes (with the exception of magnates families). We draw our conclusions with caution, as historical data carry many limitations.
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Smith-Greenaway E, Weitzman A, Chilungo A. Child Sex Composition, Parental Sex Preferences, and Marital Outcomes: Evidence From a Matrilineal Context. JOURNAL OF MARRIAGE AND THE FAMILY 2019; 81:1126-1143. [PMID: 39144153 PMCID: PMC11323038 DOI: 10.1111/jomf.12591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 04/18/2019] [Indexed: 08/16/2024]
Abstract
Objective The authors study matrilineal settings in rural Malawi, a southeast African country, to assess if women experience better marital outcomes in the presence of daughters and if so whether daughter preference plays a role. Background A provocative finding in family sociology is that couples with sons experience better marital outcomes relative to those with daughters. Sociologists contend that these marital benefits are attributable to the gender system fostering greater closeness between fathers and sons, a preference for sons, or economic, cultural, and social incentives for fathers to invest more in unions that have produced sons. Extrapolating these arguments beyond son-inspired marital benefits in patriarchal settings suggests that the reverse process-daughter-inspired marital benefits-could prevail in matrilineal contexts. Method The authors analyze three rounds of the nationally representative Malawi Demographic and Health Survey. They estimate three series of parity-specific, multivariable logistic regression models to assess the associations between child sex composition and marital outcomes (two forms of relationship abuse and polygyny) and model each outcome among the full sample of women with one to four children and control for number of children, thus conveying the average effect of sex composition across parities. Results Women with daughters-particularly women with only daughters-in predominately matrilineal, rural communities in the central and southern regions of Malawi are more likely to be in monogamous versus polygynous unions and are less likely to have experienced emotionally abusive and controlling behaviors. We find little evidence that women and men explicitly prefer or pursue daughters. Conclusion The study shows that a matrilineal gender system can influence marital dynamics in the presence of daughters even without fostering an overwhelming preference for them.
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Competitive reputation manipulation: Women strategically transmit social information about romantic rivals. JOURNAL OF EXPERIMENTAL SOCIAL PSYCHOLOGY 2018. [DOI: 10.1016/j.jesp.2018.03.011] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Spending patterns of Chinese parents on children's backpacks support the Trivers-Willard hypothesis. EVOL HUM BEHAV 2018. [DOI: 10.1016/j.evolhumbehav.2018.02.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Luo L, Ding R, Gao X, Sun J, Zhao W. Socioeconomic status influences sex ratios in a Chinese rural population. PeerJ 2017; 5:e3546. [PMID: 28674672 PMCID: PMC5494181 DOI: 10.7717/peerj.3546] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 06/15/2017] [Indexed: 11/23/2022] Open
Abstract
According to the logic of the Trivers–Willard hypothesis, in a human population, if socioeconomic status is transmitted across generations to some extent, and if sons of high-status parents tend to have higher reproductive success than daughters, while daughters of low-status parents tend to have higher reproductive success than sons, then we should expect that offspring sex ratio is positively associated with socioeconomic status. This study examines whether the assumptions and prediction of this hypothesis apply to a rural population in northern China. Results show that (1) current family socioeconomic status is positively related to family head’s father’s socioeconomic status in around 1950, (2) low-status family heads have more grandchildren through their daughters than their sons, whereas high- or middle-status family heads have more grandchildren through sons, and (3) as family heads’ status increases, they tend to produce a higher offspring sex ratio. Therefore, the assumptions and prediction of the hypothesis are met in the study population. These results are discussed in reference to past studies on sex ratio manipulation among humans.
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Affiliation(s)
- Liqun Luo
- Department of Sociology, Central China Normal University, Wuhan, China
| | - Rui Ding
- Department of Sociology, Central China Normal University, Wuhan, China
| | - Xiali Gao
- Department of Sociology, Central China Normal University, Wuhan, China
| | - Jingjing Sun
- Hubei Institute of Economic and Social Development, Central China Normal University, Wuhan, China
| | - Wei Zhao
- Department of Sociology, Central China Normal University, Wuhan, China
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Luo L, Zhao W, Weng T. Sex-Biased Parental Investment among Contemporary Chinese Peasants: Testing the Trivers-Willard Hypothesis. Front Psychol 2016; 7:1215. [PMID: 27582718 PMCID: PMC4987354 DOI: 10.3389/fpsyg.2016.01215] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 08/02/2016] [Indexed: 12/04/2022] Open
Abstract
The Trivers-Willard hypothesis predicts that high-status parents will bias their investment to sons, whereas low-status parents will bias their investment to daughters. Among humans, tests of this hypothesis have yielded mixed results. This study tests the hypothesis using data collected among contemporary peasants in Central South China. We use current family status (rated by our informants) and father's former class identity (assigned by the Chinese Communist Party in the early 1950s) as measures of parental status, and proportion of sons in offspring and offspring's years of education as measures of parental investment. Results show that (i) those families with a higher former class identity such as landlord and rich peasant tend to have a higher socioeconomic status currently, (ii) high-status parents are more likely to have sons than daughters among their biological offspring, and (iii) in higher-status families, the years of education obtained by sons exceed that obtained by daughters to a larger extent than in lower-status families. Thus, the first assumption and the two predictions of the hypothesis are supported by this study. This article contributes a contemporary Chinese case to the testing of the Trivers-Willard hypothesis.
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Affiliation(s)
- Liqun Luo
- Department of Sociology, Central China Normal University Wuhan, China
| | - Wei Zhao
- Department of Sociology, Central China Normal University Wuhan, China
| | - Tangmei Weng
- Department of Sociology, Central China Normal University Wuhan, China
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Kolk M, Schnettler S. Socioeconomic status and sex ratios at birth in Sweden: No evidence for a Trivers-Willard effect for a wide range of status indicators. Am J Hum Biol 2015; 28:67-73. [DOI: 10.1002/ajhb.22756] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 05/13/2015] [Accepted: 05/25/2015] [Indexed: 11/08/2022] Open
Affiliation(s)
- Martin Kolk
- Demography Unit; Department of Sociology; Stockholm University; Stockholm SE-106 91 Sweden
| | - Sebastian Schnettler
- Department of Sociology; Faculty of History and Sociology, University of Konstanz; D-78457 Konstanz Germany
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Stulp G, Pollet TV, Barrett L. The not-always-uniquely-predictive power of an evolutionary approach to understanding our not-so-computational nature. Front Psychol 2015; 6:419. [PMID: 25954214 PMCID: PMC4404731 DOI: 10.3389/fpsyg.2015.00419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 03/25/2015] [Indexed: 11/19/2022] Open
Affiliation(s)
- Gert Stulp
- Department of Population Health, London School of Hygiene & Tropical Medicine London, UK
| | - Thomas V Pollet
- Department of Social and Organizational Psychology, VU University Amsterdam Amsterdam, Netherlands
| | - Louise Barrett
- Department of Psychology, University of Lethbridge Lethbridge, AB, Canada
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Song S. Malnutrition, Sex Ratio, and Selection. HUMAN NATURE-AN INTERDISCIPLINARY BIOSOCIAL PERSPECTIVE 2014; 25:580-95. [DOI: 10.1007/s12110-014-9208-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Abstract
Neo-Darwinian evolution is widely acknowledged as the key framework for understanding the form and function of living systems, including myriad aspects of animal behavior. Yet extensions to human behavior and society are perennially challenged; debates are vociferous and seemingly irresolvable, and evolutionary approaches to human behavior are marginalized within much of anthropology and other social sciences. This review explores this contested terrain, arguing that although many critiques of evolutionary analyses of behavior are faulty, some valid concerns must be addressed. Human agency, behavioral plasticity, and the partial autonomy of cultural and historical change present real challenges to the standard evolutionary framework. However, several additions to the standard framework currently employed by evolutionary anthropologists and others address these concerns and provide a more comprehensive understanding of human behavioral evolution and adaptation. These additions include phenotypic adaptation, cultural transmission, gene-culture coevolution, and niche construction.
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Affiliation(s)
- Eric Alden Smith
- Department of Anthropology, University of Washington, Seattle, Washington 98195
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Rapaport LG, Kloc B, Warneke M, Mickelberg JL, Ballou JD. Do mothers prefer helpers? Birth sex-ratio adjustment in captive callitrichines. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.03.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Cognitive ability correlates positively with son birth and predicts cross-cultural variation of the offspring sex ratio. Naturwissenschaften 2013; 100:559-69. [DOI: 10.1007/s00114-013-1052-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Revised: 04/18/2013] [Accepted: 04/19/2013] [Indexed: 11/30/2022]
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Abstract
In many parts of Asia, the Middle East and North Africa, women and children are so undervalued, neglected, abused, and so often killed, that sex ratios are now strongly male biased. In recent decades, sex-biased abortion has exacerbated the problem. In this article I highlight several important insights from evolutionary biology into both the origin and the severe societal consequences of “Asia's missing women”, paying particular attention to interactions between evolution, economics and culture. Son preferences and associated cultural practices like patrilineal inheritance, patrilocality and the Indian Hindu dowry system arise among the wealthy and powerful elites for reasons consistent with models of sex-biased parental investment. Those practices then spread via imitation as technology gets cheaper and economic development allows the middle class to grow rapidly. I will consider evidence from India, China and elsewhere that grossly male-biased sex ratios lead to increased crime, violence, local warfare, political instability, drug abuse, prostitution and trafficking of women. The problem of Asia's missing women presents a challenge for applied evolutionary psychology to help us understand and ameliorate sex ratio biases and their most severe consequences.
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Affiliation(s)
- Robert Brooks
- Evolution & Ecology Research Centre and School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, Australia
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Brooks R. "Asia's missing women" as a problem in applied evolutionary psychology? EVOLUTIONARY PSYCHOLOGY 2012; 10:910-25. [PMID: 23253795 PMCID: PMC10429992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 08/10/2012] [Indexed: 06/01/2023] Open
Abstract
In many parts of Asia, the Middle East and North Africa, women and children are so undervalued, neglected, abused, and so often killed, that sex ratios are now strongly male biased. In recent decades, sex-biased abortion has exacerbated the problem. In this article I highlight several important insights from evolutionary biology into both the origin and the severe societal consequences of "Asia's missing women", paying particular attention to interactions between evolution, economics and culture. Son preferences and associated cultural practices like patrilineal inheritance, patrilocality and the Indian Hindu dowry system arise among the wealthy and powerful elites for reasons consistent with models of sex-biased parental investment. Those practices then spread via imitation as technology gets cheaper and economic development allows the middle class to grow rapidly. I will consider evidence from India, China and elsewhere that grossly male-biased sex ratios lead to increased crime, violence, local warfare, political instability, drug abuse, prostitution and trafficking of women. The problem of Asia's missing women presents a challenge for applied evolutionary psychology to help us understand and ameliorate sex ratio biases and their most severe consequences.
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Affiliation(s)
- Robert Brooks
- Evolution & Ecology Research Centre and School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, Australia.
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Wallner B, Fieder M, Seidler H. Ownership of dwelling affects the sex ratio at birth in Uganda. PLoS One 2012; 7:e51463. [PMID: 23284697 PMCID: PMC3524175 DOI: 10.1371/journal.pone.0051463] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 10/25/2012] [Indexed: 11/26/2022] Open
Abstract
Background Socio-economic conditions can affect the secondary sex ratio in humans. Mothers under good environmental conditions are predicted to increase the birth rates of sons according to the Trivers-Willard hypothesis (TWH). This study analyzed the effects of ownership and non-ownership of dwellings on the sex ratio at birth (SRB) on a Ugandan sample. Methodology/Principal Findings Our investigation included 438,640 mothers aged between 12 and 54 years. The overall average SRB was 0.5008. Mothers who live in owned dwellings gave increased births to sons (0.5019) compared to those who live in non-owned dwellings (0.458). Multivariate statistics revealed the strongest effects of dwelling ownership when controlling for demographic and social variables such as marital status, type of marriage, mothers’ age, mothers’ education, parity and others. Conclusions/Significance The results are discussed in the framework of recent plausible models dealing with the adjustment of the sex ratio. We conclude that the aspect of dwelling status could represent an important socio-economic parameter in relation to SRB variations in humans if further studies are able to analyze it between different countries in a comparative way.
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Affiliation(s)
- Bernard Wallner
- Department of Anthropology, University of Vienna, Vienna, Austria.
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Parental status and gender preferences for children: is differential fertility stopping consistent with the trivers-willard hypothesis? J Biosoc Sci 2012; 45:683-704. [PMID: 22989525 DOI: 10.1017/s0021932012000557] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Based on evolutionary reasoning, Trivers & Willard (1973) predicted status-biased sex composition and parental investment with son-preferencing effects in higher, and daughter-preferencing effects in lower status groups. Previous research shows mixed results. This study uses event-history methods and Swedish register data to study one possible mechanism in isolation: do parents in different status groups vary in their proclivities to continue fertility based on the sex composition of previous offspring? The results show no support for the Trivers-Willard hypothesis on a wide range of different status indicators. Future research on the stated hypothesis should focus on physiological rather than behavioural mechanisms.
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Pryke SR, Rollins LA. Mothers adjust offspring sex to match the quality of the rearing environment. Proc Biol Sci 2012; 279:4051-7. [PMID: 22859597 DOI: 10.1098/rspb.2012.1351] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Theory predicts that mothers should adjust offspring sex ratios when the expected fitness gains or rearing costs differ between sons and daughters. Recent empirical work has linked biased offspring sex ratios to environmental quality via changes in relative maternal condition. It is unclear, however, whether females can manipulate offspring sex ratios in response to environmental quality alone (i.e. independent of maternal condition). We used a balanced within-female experimental design (i.e. females bred on both low- and high-quality diets) to show that female parrot finches (Erythrura trichroa) manipulate primary offspring sex ratios to the quality of the rearing environment, and not to their own body condition and health. Individual females produced an unbiased sex ratio on high-quality diets, but over-produced sons in poor dietary conditions, even though they maintained similar condition between diet treatments. Despite the lack of sexual size dimorphism, such sex ratio adjustment is in line with predictions from sex allocation theory because nutritionally stressed foster sons were healthier, grew faster and were more likely to survive than daughters. These findings suggest that mothers may adaptively adjust offspring sex ratios to optimally match their offspring to the expected quality of the rearing environment.
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Affiliation(s)
- Sarah R Pryke
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
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Song S. Does famine influence sex ratio at birth? Evidence from the 1959-1961 Great Leap Forward Famine in China. Proc Biol Sci 2012; 279:2883-90. [PMID: 22456881 DOI: 10.1098/rspb.2012.0320] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The current study examined the long-term trend in sex ratio at birth between 1929 and 1982 using retrospective birth histories of 310 101 Chinese women collected in a large, nationally representative sample survey in 1982. The study identified an abrupt decline in sex ratio at birth between April 1960, over a year after the Great Leap Forward Famine began, and October 1963, approximately 2 years after the famine ended, followed by a compensatory rise between October 1963 and July 1965. These findings support the adaptive sex ratio adjustment hypothesis that mothers in good condition are more likely to give birth to sons, whereas mothers in poor condition are more likely to give birth to daughters. In addition, these findings help explain the lack of consistent evidence reported by earlier studies based on the 1944-1945 Dutch Hunger Winter or the 1942 Leningrad Siege.
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Affiliation(s)
- Shige Song
- Queens College and CUNY Institute for Demographic Research, City University of New York, Flushing, NY 11367, USA.
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Thomas F, Daoust SP, Elguero E, Raymond M. Do Mothers from Rich and Well-Nourished Countries Bear More Sons? ACTA ACUST UNITED AC 2012. [DOI: 10.4303/jem/235568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Dama MS. Sex ratio at birth and mortality rates are negatively related in humans. PLoS One 2011; 6:e23792. [PMID: 21887320 PMCID: PMC3161077 DOI: 10.1371/journal.pone.0023792] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 07/26/2011] [Indexed: 11/25/2022] Open
Abstract
Evolutionary theory posits that resource availability and parental investment ability could signal offspring sex selection, in order to maximize reproductive returns. Non-human studies have provided evidence for this phenomenon, and maternal condition around the time of conception has been identified as most important factor that influence offspring sex selection. However, studies on humans have reported inconsistent results, mostly due to use of disparate measures as indicators of maternal condition. In the present study, the cross-cultural differences in human natal sex ratio were analyzed with respect to indirect measures of condition namely, life expectancy and mortality rate. Multiple regression modeling suggested that mortality rates have distinct predictive power independent of cross-cultural differences in fertility, wealth and latitude that were earlier shown to predict sex ratio at birth. These findings suggest that sex ratio variation in humans may relate to differences in parental and environmental conditions.
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Pellegrini AD, Van Ryzin MJ, Roseth C, Bohn-Gettler C, Dupuis D, Hickey M, Peshkam A. Behavioral and social cognitive processes in preschool children's social dominance. Aggress Behav 2011; 37:248-57. [PMID: 21246568 DOI: 10.1002/ab.20385] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 11/04/2010] [Indexed: 11/12/2022]
Abstract
This longitudinal, naturalistic study addressed behavioral and social cognitive processes implicated in preschool children's social dominance. In the first objective, we examined the degree to which peer aggression, affiliation, and postaggression reconciliation predicted social dominance across a school year. Consistent with predictions, all three predicted dominance early in the year while only affiliation predicted dominance later in the year, suggesting that aggression, affiliation, and reconciliation were used to establish social dominance where affiliation was used to maintain it. In the second, exploratory, objective we tested the relative importance of social dominance and reconciliation (the Machiavellian and Vygotskian intelligence hypotheses, respectively) in predicting theory of mind/false belief. Results indicated that social dominance accounted for significant variance, beyond that related to reconciliation and affiliation, in predicting theory of mind/false belief status. Results are discussed in terms of specific behavioral and social cognitive processes employed in establishing and maintaining social dominance.
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STELKENS RIKEB, WEDEKIND CLAUS. Environmental sex reversal, Trojan sex genes, and sex ratio adjustment: conditions and population consequences. Mol Ecol 2010; 19:627-46. [DOI: 10.1111/j.1365-294x.2010.04526.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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