Social biology最新文献

This paper examines the conditions under which there might be a strong or weak relationship between childhood mortality and fertility at the micro level. The premise is that as a society undergoes transition during which a conscious effort is made to space and limit birth, the effect associated with infant death on the risk of subsequent birth reduces. Using the 1998 DHS data from Ghana and Kenya, our multivariate hazard models show that women who have experienced infant deaths tend to have a higher risk of subsequent births than those without any infant deaths at all parities studied in both countries. In a comparative context, however, the magnitude of the effect associated with infant death was weaker in Kenya at all parities, corroborating the hypothesis that the effect indeed reduces in the course of transition. Besides infant deaths, other demographic, socioeconomic and sociocultural factors were also found to associate with the risk of births. The limitations and policy implications of the findings are discussed.

In order to characterize and define human populations from a thermodynamic point of view, and considering that human societies are complex systems whose global description can be obtained by their energetic balance, the relationship was evaluated between individual energy consumption and the demographic and social-economic variables in all provinces of Spain. Pearson bivariate correlation, lineal regression analysis, and the coefficient of determination were applied. The results obtained show that individual energy consumption is associated with almost all the variables considered, in provinces with fewer than 400,000 inhabitants. However, in provinces having a population larger than 400,000, the association is reduced to about 50 percent. The positive or negative association between individual energy consumption and certain variables, especially those that determine reproductive success, suggests that the consumption of energy is explained both by the irreversible thermodynamics in relatively small populations and by the optimization principle in relatively large populations.

Historically, population researchers considered the Hutterites the champions of high fertility, since they most closely approximated the human fertility potential. Yet contemporary researchers have found evidence of a decline in fertility and a shift from natural to controlled fertility behavior among the Hutterite population. Various reasons for these recent changes have been suggested, including the use of birth control. Using interview data from a Dariusleut colony, this is the first paper to document the presence and prevalence of birth control among the North American Hutterites. All interviewed women recognized the use of birth control and reported that female sterilization was the most commonly used method. I address how the various forms of birth control and the reasons for its use relate to the Hutterite ideology.

The relationship between 27 different measures of hyperactive, impulsive, and inattentive behavior, including those considered to be more objective and those considered more influenced by social factors, is examined using a normal sample of 219 Mexican children, ages 6 to 12. Measures were based on activity monitoring by accelerometry, ethological observation of attentional and movements states in the classroom, cognitive testing using the TOVA continuous performance test (CPT), and parents' and teachers' reports on ratings scales and symptom checklists. Factor analysis was used to examine to what degree these different measures are reporting similar underlying constructs (factors) of hyperactivity and inattention. Parent and teacher ratings appear to be describing underlying constructs that are distinct from those described by the other measures, but measures based on CPT, observation, and activity monitoring did not factor together either, nor more highly correlate to each other. Analysis combining all the measures showed that parent and teacher ratings factored together based on who was reporting the behavior, rather than the behavior being reported. The findings underscore that each type of measurement of hyperactivity, impulsivity, and inattention measures a different aspect of a complex behavioral phenomenon, rather than some better measuring than others the same underlying factor.

Using data from the National Longitudinal Survey of Adolescent Health (Add Health), I investigate the relationship between birth weight and cognitive development among adolescents aged 12-17. Initial OLS regression models reveal a significant, positive relationship between low birth weight and verbal ability. Controlling for demographic, socioeconomic, and other adolescent characteristics modifies, but does not eliminate, this relationship. Additional models that stratify the sample by parental education illustrate the greater importance of other family and adolescent characteristics for cognitive development in adolescence, and a diminished role of birth weight. In the final section of the paper, fixed effects models of non-twin full siblings indicate no significant association between birth weight and verbal ability, suggesting that traditional cross-sectional models overstate the influence of birth weight for cognitive development in adolescence.

This study uses the evolutionary model to guide an exploration of the effects of body mass on aggressive and competitive behaviors among Asian-Pacific adolescents in Guam. Using a probability sample of Guam's high-school students, the results of logistic regressions suggest that adolescent females with greater body mass are more likely to engage in physical fights (aggression) and to participate in team sports (competitiveness). Ethnic differences indicate the possibility that individuals with lower body mass may be less likely to participate in physically aggressive acts and team sports. Alternate theoretical explanations for the results are also considered.

Because women are more likely than men to use social status as a criterion in mate selection, evolutionary theory has led to the hypothesis that higher proportions of males will be born to parents of high social status than to parents of low status. To date, the research that has tested this deduction has not provided consistent support. This could be partly due to the small sample size in several of the studies. The present study tested the hypothesis using 6 different social status measures provided by more than 11,000 United States and Canadian college students. The offspring sex ratio was measured by asking the students their own sex plus that of each of their siblings. No evidence was found to support the hypothesis that parental social status has any significant effect on the sex ratio of offspring.

This study examines the relationship between polygyny and child survival in light of conflicting findings reported in a number of studies. Using data from the Demographic and Health Surveys from six West African countries, the risks of neonatal, postneonatal, and overall infant mortality are estimated. Controlling for a set of social and bio-demographic factors, it is found that substantial risks of mortality are associated with polygyny. A separate analysis explores the possibility that polygyny's impact could differ from country to country. No significant interaction effects are detected, leading to the conclusion that regardless of the country in which it is practiced, polygyny still poses a challenge to the survival chances of West African children.

In contrast to cues to women's mate value (youth and physical attractiveness), many qualities that men display in lekking are socially and culturally specific. We predict that, for this reason, men avoid exposure to foreign cultures, but such xenophobia should cease once they are married (especially since the presence of their wives can function as a cross-culturally meaningful lekking device). Analyses of data from Europe and the United States confirm our predictions.