Socioeconomic Status, Institutional Power, and Body Mass Index among Chinese Adults.

Despite the vast literature on the socioeconomic status (SES) gradient of obesity among adult people, no study has investigated the relationship between institutional power and body mass index. Using national survey data from the "China Labor-force Dynamics Survey 2016" (CLDS 2016), multistage cluster-stratified probability proportional to size (PPS) sampling was employed to select cases from 29 provinces, cities, and autonomous regions in China. This study adopts an institutional approach to explore the influences of SES and institutional power on the state of being overweight or severely overweight (obese) among Chinese adults. It is shown that SES has a non-linear influence on being overweight or obese, higher education has a negative effect on being overweight or obese, income has an inverted U-shaped effect on being overweight or obese, and having a managerial or administrative job has a positive effect on being overweight but less so on obesity. These findings reveal that disparities in health outcome and risks are due to inequality in SES. The work unit is a stronger predictor of adults being overweight or obese than occupation. Working in the public sector has a positive effect on being overweight relative to working in the private sector, and only state institutions and government departments have a positive association with obesity. Our results indicate that institutional structure still has effects on individuals' life chances in the era of China's market transition.

Process of Decline in Activities of Daily Living of Older Chinese People Prior to Death: Evidence From Three Cohorts.

OBJECTIVE: The study analyzes the decline in activities of daily living (ADL) prior to death among three cohorts of older Chinese. METHOD: With data from the Chinese Longitudinal Healthy Longevity Survey, the process of decline in ADL in older people born during the periods 1899-1908, 1909-1918, and 1919-1928 is analyzed using the hierarchical linear model with mixed effects. RESULTS: The remaining survival time has a stronger effect on changes in ADL than chronological age, and there is significant heterogeneity among the older adults in ADL. CONCLUSION: Decline in ADL is delayed by extending life span. Older people with healthy behaviors, good living conditions in childhood, and age-friendly living environment have long-lasting good ADL during their remaining life span; socioeconomic resources help the older adults with ADL disabilities to survive. Selective effects of mortality and protective effects of socioeconomic resources explain the heterogeneity in ADL and its changes over time.

Interpreting polygenic scores, polygenic adaptation, and human phenotypic differences.

Recent analyses of polygenic scores have opened new discussions concerning the genetic basis and evolutionary significance of differences among populations in distributions of phenotypes. Here, we highlight limitations in research on polygenic scores, polygenic adaptation and population differences. We show how genetic contributions to traits, as estimated by polygenic scores, combine with environmental contributions so that differences among populations in trait distributions need not reflect corresponding differences in genetic propensity. Under a null model in which phenotypes are selectively neutral, genetic propensity differences contributing to phenotypic differences among populations are predicted to be small. We illustrate this null hypothesis in relation to health disparities between African Americans and European Americans, discussing alternative hypotheses with selective and environmental effects. Close attention to the limitations of research on polygenic phenomena is important for the interpretation of their relationship to human population differences.

Female fertility history and mid-late-life health: Findings from China.

China's middle-aged and older women suffer from poorer health than men. Using national baseline data from the China Health and Retirement Longitudinal Study (CHARLS), a survey conducted from 2011 to 2012, this article applies logistic models to investigate the association between female fertility history (parity, early childbearing, late childbearing) and middle-aged and late-life health. We find that parity is related to the mid-late-life health of women. Women with four children or more are more likely to suffer from activities of daily living (ADL) impairment and poorer self-rated health than those with one to three children. Early childbearing is associated with ADL impairment; however, the correlation is mediated by socioeconomic status. Early childbearing is related to self-rated health in later life by an indirect-only mediation effect via educational attainment and personal income.

Marriage Squeeze and Intergenerational Support in Contemporary Rural China: Evidence from X County of Anhui Province.

With China's gender imbalance and increasingly severe male marriage squeeze, patterns of intergenerational support in rural areas are likely to undergo significant change. Using data from a survey of four towns from X county in Anhui province carried out in 2008, this article analyzes the effects of sons' marital status on intergenerational support. Random-effect regression analysis shows that son's marital status has strong effects on financial support to and coresidence with parents. Compared with married sons, older unmarried sons (so-called forced bachelors) tend to provide less financial support to their parents and are more likely to live with their parents. Parents' support of sons, as well as the parents' own needs and sons' capabilities all affect the support provided by sons. These results show that both theories of exchange and altruism are simultaneously relevant in the context of the marriage squeeze of contemporary rural China.

Natural capital and ecosystem services informing decisions: From promise to practice.

The central challenge of the 21st century is to develop economic, social, and governance systems capable of ending poverty and achieving sustainable levels of population and consumption while securing the life-support systems underpinning current and future human well-being. Essential to meeting this challenge is the incorporation of natural capital and the ecosystem services it provides into decision-making. We explore progress and crucial gaps at this frontier, reflecting upon the 10 y since the Millennium Ecosystem Assessment. We focus on three key dimensions of progress and ongoing challenges: raising awareness of the interdependence of ecosystems and human well-being, advancing the fundamental interdisciplinary science of ecosystem services, and implementing this science in decisions to restore natural capital and use it sustainably. Awareness of human dependence on nature is at an all-time high, the science of ecosystem services is rapidly advancing, and talk of natural capital is now common from governments to corporate boardrooms. However, successful implementation is still in early stages. We explore why ecosystem service information has yet to fundamentally change decision-making and suggest a path forward that emphasizes: (i) developing solid evidence linking decisions to impacts on natural capital and ecosystem services, and then to human well-being; (ii) working closely with leaders in government, business, and civil society to develop the knowledge, tools, and practices necessary to integrate natural capital and ecosystem services into everyday decision-making; and (iii) reforming institutions to change policy and practices to better align private short-term goals with societal long-term goals.

Impacts of conservation and human development policy across stakeholders and scales.

Ideally, both ecosystem service and human development policies should improve human well-being through the conservation of ecosystems that provide valuable services. However, program costs and benefits to multiple stakeholders, and how they change through time, are rarely carefully analyzed. We examine one of China's new ecosystem service protection and human development policies: the Relocation and Settlement Program of Southern Shaanxi Province (RSP), which pays households who opt voluntarily to resettle from mountainous areas. The RSP aims to reduce disaster risk, restore important ecosystem services, and improve human well-being. We use household surveys and biophysical data in an integrated economic cost-benefit analysis for multiple stakeholders. We project that the RSP will result in positive net benefits to the municipal government, and to cross-region and global beneficiaries over the long run along with environment improvement, including improved water quality, soil erosion control, and carbon sequestration. However, there are significant short-run relocation costs for local residents so that poor households may have difficulty participating because they lack the resources to pay the initial costs of relocation. Greater subsidies and subsequent supports after relocation are necessary to reduce the payback period of resettled households in the long run. Compensation from downstream beneficiaries for improved water and from carbon trades could be channeled into reducing relocation costs for the poor and sharing the burden of RSP implementation. The effectiveness of the RSP could also be greatly strengthened by early investment in developing human capital and environment-friendly jobs and establishing long-term mechanisms for securing program goals. These challenges and potential solutions pervade ecosystem service efforts globally.

Bequest Motives of older people in Rural China: From the Perspective of Intergenerational Support.

China, a society long characterized by traditional Confucianism and the practice of filial piety, is undergoing dramatic socioeconomic development and erosion of traditions. In this rapidly changing context, the motives behind rural parental bequests have not been well studied. This paper draws on a survey conducted in rural Anhui province of China and uses hierarchical linear models (HLM) to examine whether three kinds of support from children are associated with older parents' bequest motives. We find that while instrumental support accords with an exchange model of motivation, financial transfer is consistent with an altruistic motivation for parental bequest plans. Offspring gender is strongly associated with parental planning of bequests, when only sons are considered; family division is a strong correlate of parents' bequest plan and reflects exchange motivation. These findings have important implications for research on traditional culture and an evolving social security system.

Evolution of division of labor: emergence of different activities among group members.

The division of labor is an important component of the organization of human society. However, why this division evolved in hominids requires further investigation. Archeological evidence suggests that it appeared after the emergence of Homo sapiens and contributed to the great success of our species. We develop a mathematical model to investigate under what conditions division of labor should evolve. We assume two types of resources the acquisition of which demands different skills, and study the evolution of the strategy that an individual should use to divide its lifetime into learning and using each skill. We show that division of labor likely evolves when group size is large, skill learning is important for acquiring resources, and there is food sharing within a group. We also investigate division of labor by gender under the assumption that the genders have different efficiencies in acquiring each resource. We show that division of labor by gender likely evolves when skill learning is important and the difference in efficiencies between genders in acquiring resources is large. We discuss how the results of our analysis might apply to the evolution of division of labor in hominids.

On the stability of the Bayenv method in assessing human SNP-environment associations.

BACKGROUND: Phenotypic variation along environmental gradients has been documented among and within many species, and in some cases, genetic variation has been shown to be associated with these gradients. Bayenv is a relatively new method developed to detect patterns of polymorphisms associated with environmental gradients. Using a Bayesian Markov Chain Monte Carlo (MCMC) approach, Bayenv evaluates whether a linear model relating population allele frequencies to environmental variables is more probable than a null model based on observed frequencies of neutral markers. Although this method has been used to detect environmental adaptation in a number of species, including humans, plants, fish, and mosquitoes, stability between independent runs of this MCMC algorithm has not been characterized. In this paper, we explore the variability of results between runs and the factors contributing to it. RESULTS: Independent runs of the Bayenv program were carried out using genome-wide single-nucleotide polymorphism (SNP) data from samples from 60 worldwide human populations following previous applications of the Bayenv method. To assess factors contributing to the method's stability, we used varying numbers of MCMC iterations and also analyzed a second modified data set that excluded two Siberian populations with extreme climate variables. Between any two runs, correlations between Bayes factors and the overlap of SNPs in the empirical p value tails were surprisingly low. Enrichments of genic versus non-genic SNPs in the empirical tails were more robust than the empirical p values; however, the significance of the enrichments for some environmental variables still varied among runs, contradicting previously published conclusions. Runs with a greater number of MCMC iterations slightly reduced run-to-run variability, and excluding the Siberian populations did not have a large effect on the stability of the runs. CONCLUSIONS: Because of high run-to-run variability, we advise against making conclusions about genome-wide patterns of adaptation based on only one run of the Bayenv algorithm and recommend caution in interpreting previous studies that have used only one run. Moving forward, we suggest carrying out multiple independent runs of Bayenv and averaging Bayes factors between runs to produce more stable and reliable results. With these modifications, future discoveries of environmental adaptation within species using the Bayenv method will be more accurate, interpretable, and easily compared between studies.

The spread of inequality.

The causes of socioeconomic inequality have been debated since the time of Plato. Many reasons for the development of stratification have been proposed, from the need for hierarchical control over large-scale irrigation systems to the accumulation of small differences in wealth over time via inheritance processes. However, none of these explains how unequal societies came to completely displace egalitarian cultural norms over time. Our study models demographic consequences associated with the unequal distribution of resources in stratified societies. Agent-based simulation results show that in constant environments, unequal access to resources can be demographically destabilizing, resulting in the outward migration and spread of such societies even when population size is relatively small. In variable environments, stratified societies spread more and are also better able to survive resource shortages by sequestering mortality in the lower classes. The predictions of our simulation are provided modest support by a range of existing empirical studies. In short, the fact that stratified societies today vastly outnumber egalitarian societies may not be due to the transformation of egalitarian norms and structures, but may instead reflect the more rapid migration of stratified societies and consequent conquest or displacement of egalitarian societies over time.

Rural household income and inequality under the Sloping Land Conversion Program in western China.

As payment for ecosystem services (PES) programs proliferate globally, assessing their impact upon households' income and livelihood patterns is critical. The Sloping Land Conversion Program (SLCP) is an exceptional PES program, in terms of its ambitious biophysical and socioeconomic objectives, large geographic scale, numbers of people directly affected, and duration of operation. The SLCP has now operated in the poor mountainous areas in China for 10 y and offers a unique opportunity for policy evaluation. Using survey data on rural households' livelihoods in the southern mountain area in Zhouzhi County, Shaanxi Province, we carry out a statistical analysis of the effects of PES and other factors on rural household income. We analyze the extent of income inequality and compare the socio-demographic features and household income of households participating in the SLCP with those that did not. Our statistical analysis shows that participation in SLCP has significant positive impacts upon household income, especially for low- and medium-income households; however, participation also has some negative impacts on the low- and medium-income households. Overall, income inequality is less among households participating in the SLCP than among those that do not after 7 y of the PES program. Different income sources have different effects on Gini statistics; in particular, wage income has opposite effects on income inequality for the participating and nonparticipating households. We find, however, that the SLCP has not increased the transfer of labor toward nonfarming activities in the survey site, as the government expected.

The influence of social niche on cultural niche construction: modelling changes in belief about marriage form in Taiwan.

With introduction of social niche effects into a model of cultural change, the frequency of a practice cannot predict the frequency of its underlying belief. The combination of a general model with empirical data from a specific case illustrates the importance of collaboration between modellers and field researchers, and identifies the type of quantitative data necessary for analysing case studies. Demographic data from colonial-period household registers in Taiwan document a shift in marriage form within 40 years, from a mixture of uxorilocal marriages and virilocal marriages to the latter's dominance. Ethnographic data indicate marriage-related beliefs, costs, ethnic effects and colonial policies as well as the importance of horizontal cultural transmission. We present a formal model for the effects of moral beliefs about marriage and a population economic index on the decline of uxorilocal marriage. We integrate empirical marriage rates and an estimated economic index to produce five projections of the historical frequencies of one belief. These projections demonstrate how economic development may affect a cultural niche. They also indicate the need for future research on the relationship between wealth and cultural variability, the motivational force of cultural versus social factors, and the process of cultural niche construction.

On the classification of epistatic interactions.

Modern genomewide association studies are characterized by the problem of "missing heritability." Epistasis, or genetic interaction, has been suggested as a possible explanation for the relatively small contribution of single significant associations to the fraction of variance explained. Of particular concern to investigators of genetic interactions is how to best represent and define epistasis. Previous studies have found that the use of different quantitative definitions for genetic interaction can lead to different conclusions when constructing genetic interaction networks and when addressing evolutionary questions. We suggest that instead, multiple representations of epistasis, or epistatic "subtypes," may be valid within a given system. Selecting among these epistatic subtypes may provide additional insight into the biological and functional relationships among pairs of genes. In this study, we propose maximum-likelihood and model selection methods in a hypothesis-testing framework to choose epistatic subtypes that best represent functional relationships for pairs of genes on the basis of fitness data from both single and double mutants in haploid systems. We gauge the performance of our method with extensive simulations under various interaction scenarios. Our approach performs reasonably well in detecting the most likely epistatic subtype for pairs of genes, as well as in reducing bias when estimating the epistatic parameter (epsilon). We apply our approach to two available data sets from yeast (Saccharomyces cerevisiae) and demonstrate through overlap of our identified epistatic pairs with experimentally verified interactions and functional links that our results are likely of biological significance in understanding interaction mechanisms. We anticipate that our method will improve detection of epistatic interactions and will help to unravel the mysteries of complex biological systems.

Coevolution of adaptive technology, maladaptive culture and population size in a producer-scrounger game.

Technology (i.e. tools, methods of cultivation and domestication, systems of construction and appropriation, machines) has increased the vital rates of humans, and is one of the defining features of the transition from Malthusian ecological stagnation to a potentially perpetual rising population growth. Maladaptations, on the other hand, encompass behaviours, customs and practices that decrease the vital rates of individuals. Technology and maladaptations are part of the total stock of culture carried by the individuals in a population. Here, we develop a quantitative model for the coevolution of cumulative adaptive technology and maladaptive culture in a 'producer-scrounger' game, which can also usefully be interpreted as an 'individual-social' learner interaction. Producers (individual learners) are assumed to invent new adaptations and maladaptations by trial-and-error learning, insight or deduction, and they pay the cost of innovation. Scroungers (social learners) are assumed to copy or imitate (cultural transmission) both the adaptations and maladaptations generated by producers. We show that the coevolutionary dynamics of producers and scroungers in the presence of cultural transmission can have a variety of effects on population carrying capacity. From stable polymorphism, where scroungers bring an advantage to the population (increase in carrying capacity), to periodic cycling, where scroungers decrease carrying capacity, we find that selection-driven cultural innovation and transmission may send a population on the path of indefinite growth or to extinction.

Intergenerational support and subjective health of older people in rural China: a gender-based longitudinal study.

AIM: To examine gender differences in the effect of intergenerational exchanges on subjective health of Chinese rural elderly. METHODS: Using the data from three waves of the survey 'Well-being of Elderly in Anhui Province, China' conducted in 2001, 2003 and 2006, respectively, this study uses random effect logit models for men and women separately. RESULTS: While an increase in instrumental support from children to older people is associated with deterioration in the subjective health of older men, financial support from older people to children is associated with improvement in the formers' subjective health. Although an increase in instrumental support from older people to children, and mutual emotional support is associated with improved subjective health of older women, financial support from children to older women has a negative effect on the latter's subjective health. CONCLUSIONS: Reciprocal intergenerational transfers contribute to improvement in subjective health of older people, while increased support through demand-based transfers appears to result in deterioration of their health.

Economics, cultural transmission, and the dynamics of the sex ratio at birth in China.

In rural China, the ratio of newborn boys to newborn girls [sex ratio at birth (SRB)] has been rising for several decades, to values significantly above its biological norm. This trend has a number of alarming societal consequences, and has attracted the attention of scholars and politicians. The root of the problem lies in a 2,500-year-old culture of son preference. This culture is intricately linked with the economic reality of each couple's life, so that there are financial and psychological repercussions to parents who have no sons. To bring greater clarity and understanding to this issue, we present a quantitative framework that describes the interaction between economics and cultural transmission. We start with an explicit mechanism by which economic incentives can change cultural beliefs of a given individual, and go on to include a mechanism of cultural inheritance from generation to generation. We then show how economic conditions can affect the dynamics of cultural change in an entire society, and may lead to a decrease in the country's sex ratio at birth.

Cultural coevolution of norm adoption and enforcement when punishers are rewarded or non-punishers are punished.

A number of studies have shown that social norms can be maintained at a high frequency when norm-violators are punished. However, there remains the problem of how norm-adopters and punishers coevolve within a single group. We develop a recursive system to examine the coevolution of norm-adopters and punishers where the viability of punishers is enhanced by one of two "metanorms": (1) Norm-observers reward punishers for punishing norm-violators (Reward Model); (2) Punishers punish non-punishers (Punishment Model). Both models generate a bistable system and each is characterized in phenotype frequency space by a distinct region of attraction to the equilibrium consisting of only norm-adopting punishers. Using a Monte Carlo simulation, we find that cultural drift may allow norm-adopters and punishers to coevolve from invasion into this region of attraction, resulting in their fixation. This coevolution typically occurs across a wider range of conditions under the reward- than the punishment-based metanorm. We also show that, under appropriate conditions, a large negative statistical association between the two traits may evolve only under the Reward Model. Furthermore, for each metanorm, a population of norm-adopters who always observe the norm can be locally stable over a continuum of punishment frequencies.

Marriage form and age at first marriage: a comparative study in three counties in contemporary rural China.

Using data from two surveys in three counties in which the prevalence of uxorilocal marriage differs greatly, this article analyzes the effects of marriage form, individual, family, and social factors on age at first marriage and spousal age difference. The results show that, under the Chinese patrilineal joint family system, compared with the dominant virilocal marriage form, uxorilocal marriage significantly lowers women's age at first marriage, increases men's age at first marriage, and consequently increases spousal age difference. Education, number of brothers, adoption status, marriage arrangement, and marriage circle also significantly affect age at first marriage for both genders. Age at first marriage and spousal age difference vary greatly among the three counties. These findings address the process and consequences of change in rural family and marriage customs during the current demographic and social transition and may help to promote later marriage and later childbearing under the present low fertility conditions in rural China.

Gender differences in child survival in contemporary rural China: a county study.

Using data from a survey of deaths of children less than 5 years old conducted in 1997 in a county in Shaanxi Province, China, this paper examines gender differences in child survival in contemporary rural China. First, excess female child mortality in the county in 1994-96 is described, followed by an analysis of the mechanisms whereby the excess mortality takes place, and the underlying social, economic and cultural factors behind it. Excess female child mortality in this county is probably caused primarily by discrimination against girls in curative health care rather than in preventive health care or food and nutrition. Although discrimination occurs in all kinds of families and communities, discrimination itself is highly selective, and is primarily against girls with some specific characteristics. It is argued that the excess mortality of girls is caused fundamentally by the strong son preference in traditional Chinese culture, but exacerbated by the government-guided family planning programme and regulations. This suggests that it is crucial to raise the status of girls within the family and community so as to mitigate the pressures to discriminate against girls in China's low fertility regime. Finally, the possible policy options to improve female child survival in contemporary rural China are discussed.