Evidence of adaptive intergenerational sex ratio adjustment in contemporary human populations.

Using the abrupt decline in sex ratio at birth in China during and immediately after the 1959-1961 Great Leap Forward Famine in China as a natural experiment, this study conducts difference-in-differences analysis to test the hypothesis that changes in the sex ratio at birth of the maternal generation can produce adaptive changes in the sex ratio at birth of the offspring generation toward the opposite direction, which was derived from the developmental and evolutionary psychological literature on female reproductive strategy. The results show that, after controlling for sex-selective abortion, the decline in the sex ratio at birth in 1962-1964 caused a substantial increase in the sex ratio at birth among children whose mothers were born in 1963. Such finding suggests the presence of adaptive intergenerational sex ratio adjustment in humans.

Assessing the impact of in utero exposure to famine on fecundity: evidence from the 1959-61 famine in China.

This study identifies a significant increase in sterility among rural, but not urban, Chinese women who were conceived and born during the 1959-61 famine that resulted from the Great Leap Forward. Applied to data from two large-scale, nationally representative, sample surveys of Chinese women of childbearing age conducted in 1997 and 2001 by the State Family Planning Commission, difference-in-differences analysis revealed that exposure to the famine while in the womb caused an increase in the risk of sterility amongst the adult women surveyed of 1.1 per cent. This is a substantial increase given that the overall prevalence of primary and permanent sterility is only slightly over 1 per cent in China. These findings support the hypothesis that a woman exposed to acute malnutrition while in the womb may experience a long-term negative impact on her reproductive system, which could result in permanently impaired fecundity.

Does famine influence sex ratio at birth? Evidence from the 1959-1961 Great Leap Forward Famine in China.

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.

Whole Genome Characterization and Genetic Evolution Analysis of a New Ostrich Parvovirus.

Ostrich diseases characterized by paralysis have been breaking out in broad areas of China since 2015, causing major damage to the ostrich breeding industry in China. This report describes a parvovirus detected in ostriches from four different regions. The entire genomes of four parvovirus strains were sequenced following amplification by PCR, and we conducted comprehensive analysis of the ostrich parvovirus genome. Results showed that the length genomes of the parvovirus contained two open reading frames. Ostrich parvovirus (OsPV) is a branch of goose parvovirus (GPV). Genetic distance analysis revealed a close relationship between the parvovirus and goose parvovirus strains from China, with the closest being the 2016 goose parvovirus RC16 strain from Chongqing. This is the first report of a parvovirus in ostriches. However, whether OsPV is the pathogen of ostrich paralysis remains uncertain. This study contributes new information about the evolution and epidemiology of parvovirus in China, which provides a new way for the study of paralysis in ostriches.

Famine, death, and madness: schizophrenia in early adulthood after prenatal exposure to the Chinese Great Leap Forward Famine.

Using data from large scale, nationally representative sample surveys, we tested the hypothesis that prenatal exposure to famine increases schizophrenia risk at adulthood by studying the Great Leap Forward Famine in China (1959-1961). Our results show that, in the urban population, being conceived and born during the famine increased the risk of developing schizophrenia at early adulthood as compared to both the pre-famine and post-famine cohorts. In the rural population, however, the post-famine cohort had the highest risk of developing schizophrenia, and there was virtually no difference in schizophrenia risk between the pre-famine and the famine cohort. This finding contrasts sharply with previous studies on the Dutch Hunger Winter as well as with smaller scale local studies in China based on hospital records. We offer an explanation for the urban-rural difference in the schizophrenia-famine relationship based on population selection by differential excess mortality and provide supportive evidence through province- and cohort-level ecological analysis.

Does famine have a long-term effect on cohort mortality? Evidence from the 1959-1961 great leap forward famine in China.

Using retrospective individual mortality records of three cohorts of newborns (1954-1958, 1959-1962 and 1963-1967) from a large national fertility survey conducted in 1988 in China, this paper examines the effect of being conceived or born during the 1959-1961 Great Leap Forward Famine on postnatal mortality. The results show strong evidence of a short-term (period) effect of the famine, caused directly by starvation or severe malnutrition during the period of the famine. After controlling for period mortality fluctuation, however, the famine-born cohort does not show higher mortality than either the pre-famine or the post-famine cohort. Aggregate-level cross-temporal comparisons using published cohort population counts from China's 1982 Census, 1990 Census, 1995 micro-Census, 2000 Census and 2005 micro-Census lead to the same conclusion. The relevance of these new findings for the 'fetal origins' hypothesis and the selection effect hypothesis is discussed.

Does son preference influence children's growth in height? A comparative study of Chinese and Filipino children.

Research has demonstrated that son preference has a serious impact on the survival and well-being of female infants and children in some parts of South and East Asia, but little is known about the consequences of son preference in later childhood and adolescence. We compare children's growth trajectories in height over childhood and adolescence in China, where the level of son preference is relatively high, and the Philippines, where it is relatively low. Children's height reflects long-term nutritional status and exposure to infectious diseases, both influenced by household decision-making and, presumably, by a preference for sons. Using data from two high-quality longitudinal studies and multilevel growth models, we find that male children in China show an additional height advantage relative to their female counterparts, when compared to the sex difference in growth trajectories in the Philippines. Further analysis reveals that the additional advantage of males in China is stronger in rural areas.

Exodus from Hunger: The Long-Term Health Consequences of the 1959-1961 Chinese Famine.

This article examines the long-term health consequences of China's 1959-1961 famine by comparing people who stayed in Guangdong and endured the famine with people who crossed the border to immigrate to Hong Kong and thus escaped the famine. Based on data from the Hong Kong Panel Study of Social Dynamics (HKPSSD) and the China Family Panel Studies (CFPS), we focused on two health indicators-body mass index (BMI) and self-rated health (SRH)-of the cohort born before 1959. Our results show that the stayers who experienced the famine have a lower BMI than the emigrants, and they are likely to have a poor SRH. The difference-in-differences (DID) estimates further show that the famine exposure reduced the odds of giving higher ratings of SRH by 60 and 42 percent, respectively, for the 1923-1940 and 1941-1958 birth cohorts. For the 1923-1940 cohort, famine exposure also reduced their BMI by 1.5 points.

Privation, stress, and human sex ratio at birth.

This article reviews the growing interdisciplinary literature on the effect of privation and stress on human sex ratio at birth. Borrowing strength from the potential outcomes causal analysis framework, the discussion focuses on the issues of study design and identification strategy and how they have influenced the current state of the field. The review suggests that much of the inconsistency in the literature regarding the effect of privation and stress on human sex ratio at birth is due to the weak designs and over-simplistic identification strategies used in previous studies. Studies based on natural experimental designs and well-thought-out identification strategies, on the other hand, have produced rather compelling and consistent evidence suggesting that maternal privation and stress during pregnancy reduce male births.

Malnutrition, sex ratio, and selection: a study based on the great leap forward famine.

This study tests the evolutionary hypothesis that maternal nutritional condition can influence offspring sex ratio at birth in humans. Using the 1959-1961 Chinese Great Leap Forward famine as a natural experiment, this study combines two large-scale national data sources and difference-in-differences method to identify the effect of famine-induced acute malnutrition on sex ratio at birth. The results show a significant famine-induced decrease in the proportion of male births in the 1958, 1961, and 1964 in the urban population but not in the rural population. Given that both the urban and rural populations suffered from the famine-induced malnutrition, and that the rural population experienced a drastic famine-induced mortality increase and fertility reduction, these results suggest the presence of a short-term famine effect, a long-term famine effect, and a selection effect. The timing of the estimated famine effects suggests that famine influences sex ratio at birth by differential implantation and differential fetal loss by fetal sex.

Identifying the intergenerational effects of the 1959-1961 Chinese Great Leap Forward Famine on infant mortality.

Using the 1959-1961 Chinese Great Leap Forward Famine as a natural experiment, this study examines the relationship between mothers' prenatal exposure to acute malnutrition and their children's infant mortality risk. According to the results, the effect of mothers' prenatal famine exposure status on children's infant mortality risk depends on the level of famine severity. In regions of low famine severity, mothers' prenatal famine exposure significantly reduces children's infant mortality, whereas in regions of high famine severity, such prenatal exposure increases children's infant mortality although the effect is not statistically significant. Such a curvilinear relationship between mothers' prenatal malnutrition status and their children's infant mortality risk is more complicated than the linear relationship predicted by the original fetal origins hypothesis but is consistent with the more recent developmental origins of health and disease theory.

Dynamics of inequality: mother's education and infant mortality in China, 1970-2001.

In this study, the authors analyze the dynamic relationship between Chinese women's education, their utilization of newly available medical pregnancy care, and their infants' mortality risk. China has undergone enormous social, economic, and political changes over recent decades and is a novel context in which to examine the potential influence of social change and technological innovation on health disparities. The authors consider efficacy, or the ability to quickly absorb and effectively utilize new medical innovations, and argue that the social stratification of efficacy provides an important conceptual link between education and the greater likelihood of benefitting from medical innovations. Using the 2001 National Family Planning and Reproductive Health Survey data and multilevel, multiprocess models, the authors show that Chinese infants born to better educated mothers retained a survival advantage over the turbulent decades between 1970 and 2000. This occurs largely because educated mothers more actively sought prenatal care and professional delivery assistance use.

Mortality consequences of the 1959-1961 Great Leap Forward famine in China: Debilitation, selection, and mortality crossovers.

Using retrospective mortality records for three cohorts of newborns (1956-1958, 1959-1961, and 1962-1964) drawn from a large Chinese national fertility survey conducted in 1988, this article examines cohort mortality differences up to age 22, with the aim of identifying debilitating and selection effects of the 1959-1961 Great Leap Forward Famine. The results showed that the mortality level of the non-famine cohort caught up to and exceeded the level of the famine cohort between ages 11 and 12, suggesting both debilitating and selection effects. Multilevel multiprocess models further established a more direct connection between frailties in infancy and frailties at subsequent ages, revealing the underlying dynamics of mortality convergence between the famine and the non-famine cohorts caused by differential excess infant mortality. These results provide important new insights into the human mortality process.

Ageing, the urban-rural gap and disability trends: 19 years of experience in China - 1987 to 2006.

BACKGROUND: As the age of a population increases, so too does the rate of disability. In addition, disability is likely to be more common in rural compared with urban areas. The present study aimed to examine the influence of rapid population changes in terms of age and rural/urban residence on the prevalence of disability. METHODS: Data from the 1987 and 2006 China Sampling Surveys on Disability were used to estimate the impacts of rapid ageing and the widening urban-rural gap on the prevalence of disability. Stratum specific rates of disability were estimated by 5-year age-group and type of residence. The decomposition of rates method was used to calculate the rate difference for each stratum between the two surveys. RESULTS: The crude disability rate increased from 4.89% in 1987 to 6.39% in 2006, a 1.5% increase over the 19 year period. However, after the compositional effects from the overall rates of changing age-structure in 1987 and 2006 were eliminated by standardization, the disability rate in 1987 was 6.13%, which is higher than that in 2006 (5.91%). While in 1987 the excess due to rural residence compared with urban was <1.0%, this difference increased to >1.5% by 2006, suggesting a widening disparity by type of residence. When rates were decomposed, the bulk of the disability could be attributed to ageing, and very little to rural residence. However, a wider gap in prevalence between rural and urban areas could be observed in some age groups by 2006. CONCLUSION: The increasing number of elderly disabled persons in China and the widening discrepancy of disability prevalence between urban and rural areas may indicate that the most important priorities for disability prevention in China are to reinforce health promotion in older adults and improve health services in rural communities.