Trait-specific sensitive developmental windows: Wing growth best integrates weather conditions encountered throughout the development of nestling Alpine swifts.

The size and growth patterns of nestling birds are key determinants of their survival up to fledging and long-term fitness. However, because traits such as feathers, skeleton and body mass can follow different developmental trajectories, our understanding of the impact of adverse weather on development requires insights into trait-specific sensitive developmental windows. We analysed data from nestling Alpine swifts in Switzerland measured throughout growth up to the age of 50 days (i.e. fledging between 50 and 70 days), for wing length and body mass (2693 nestlings in 25 years) and sternum length (2447 nestlings in 22 years). We show that the sensitive developmental windows for wing and sternum length corresponded to the periods of trait-specific peak growth, which span almost the whole developmental period for wings and the first half for the sternum. Adverse weather conditions during these periods slowed down growth and reduced size. Although nestling body mass at 50 days showed the greatest inter-individual variation, this was explained by weather in the two days before measurement rather than during peak growth. Interestingly, the relationship between temperature and body mass was not linear, and the initial sharp increase in body mass associated with the increase in temperature was followed by a moderate drop on hot days, likely linked to heat stress. Nestlings experiencing adverse weather conditions during wing growth had lower survival rates up to fledging and fledged at later ages, presumably to compensate for slower wing growth. Overall, our results suggest that measures of feather growth and, to some extent, skeletal growth best capture the consequences of adverse weather conditions throughout the whole development of offspring, while body mass better reflects the short, instantaneous effects of weather conditions on their body reserves (i.e. energy depletion vs. storage in unfavourable vs. favourable conditions).

Juvenile survival curves in a solitary ground squirrel with a prolonged hibernation: effects of individual characteristics, environment, and maternal investment.

Juvenile survival is a key life-history influence on population dynamics and adaptive evolution. We analyzed the effects of individual characteristics, early environment, and maternal investment on juvenile survival in a large solitary hibernating rodent-yellow ground squirrel Spermophilus fulvus using Cox mixed-effects models. Only 48% of weaned pups survived to dispersal and 17% survived to hibernation. Early life expectancy was primarily determined by individual characteristics and, to a lesser extent, by the early environment. The strongest and positive predictor of juvenile survival was body mass which crucially affected mortality immediately after weaning. Males suffered higher mortality than females after the onset of dispersal; however, the overall difference between sexes was partly masked by high rates of mortality in the first days after emergence in both sexes. Later emerged juveniles had lower life expectancy than the earliest pups. The overall effect of local juvenile density was positive. Prolonged lactation did not enhance juvenile survival: Pups nursed longer survived shorter than the young nursed for a shorter period. Our findings support the hypothesis that females of S. fulvus cannot effectively regulate maternal expenditures to mitigate the effects of unfavorable conditions on their offspring. The strategy to deal with seasonal time constraints on life history in female S. fulvus suggests an early termination of maternal care at the cost of juvenile quality and survival. This female reproductive strategy corresponds to a "fast-solitary" life of folivorous desert-dwelling S. fulvus and other solitary ground squirrels with prolonged hibernation.

Using data on biomarkers and siblings to study early-life economic determinants of type-2 diabetes.

We study the effect of economic conditions early in life on the occurrence of type-2 diabetes in adulthood using contextual economic indicators and within-sibling pair variation. We use data from Lifelines: a longitudinal cohort study and biobank including 51,270 siblings born in the Netherlands from 1950 onward. Sibling fixed-effects account for selective fertility. To identify type-2 diabetes we use biomarkers on the hemoglobin A1c concentration and fasting glucose in the blood. We find that adverse economic conditions around birth increase the probability of type-2 diabetes later in life both in males and in females. Inference based on self-reported diabetes leads to biased results, incorrectly suggesting the absence of an effect. The same applies to inference that does not account for selective fertility.

Parental nonemployment in childhood and children's health later in life.

While the effects of joblessness on the health of the non-employed are well-documented, its long-term spillover consequences on the health of their relatives, especially children, remain poorly understood. This research explores the long-term associations of parental nonemployment spells experienced during early, mid and late childhood on children's mental and physical health. The analysis exploits data drawn from the British Household Panel Survey (BHPS) and the UK Household Longitudinal Study (UKHLS), linking detailed parental socioeconomic information with their children between the years 1993 and 2013. This paper employs a Correlated Random Effects (CRE) probit model that allows accounting for unobserved heterogeneity as well as a non-linear Generalized Estimating Equations (GEE) random effects estimator accounting in addition for the dependency structure of the data. Results indicate that experiencing parental nonemployment during early and late childhood has a negative association on the children's likelihood of suffering from long-standing illnesses later in life, while experiencing parental nonemployment during middle childhood negatively affects the young adult's mental health. Moreover, experiencing parental nonemployment during late childhood increases the probability of both reporting poor or fair self-assessed health and the likelihood of consuming prescribed medicines in early adulthood. However, there seems to be a considerable effect heterogeneity by family socioeconomic status, parents' gender, and frequencies of parental nonemployment spells. Current adulthood circumstances, such as level of educational attainment, job situation and household demographics, are used to explore the potential mechanisms affecting results. These findings may help policymakers shape appropriate responses to mitigate the psychological and physical burden derived from parental nonemployment, especially among already disadvantaged households.

Short Lives: The Impact of Parental Death on Early-Life Mortality and Height in the Netherlands, 1850-1940.

We investigate how experiencing parental death in infancy, childhood, or adolescence affected individuals' health using two distinct measures: mortality before age 20 and young adult height. Using two complementary indicators of health enables us to gain more insights into processes of selection and the scarring of health. Employing nationally representative data for the Netherlands for the 1850-1940 period, we analyze the survival of roughly 36,000 boys and girls using Cox proportional hazard models, and the stature of more than 4,000 young adult men using linear regression models. Results show that losing a parent-particularly a mother-at an early age (0-1 or 1-5) was related to a strongly increased risk of mortality. We find no evidence that losing a parent at these ages affected stature in young adulthood. For boys, experiencing maternal death between ages five and 12 was strongly associated with a shorter young adult height; however, we did not find evidence for an association between experiencing paternal death and shorter stature. We conclude that stature may not be a particularly good measure of the effects of early-life adversity if the health shock greatly increases mortality, as these effects create potential issues of health selection.

Exposure in utero to adverse events and health late-in-life: Evidence from China.

This paper estimates the effect of in utero exposure to adverse events on late life diabetes, cardiovascular disease risks and cognition deficiency. We merge data on the regional violence during the Cultural Revolution and the excessive death rates during the Chinese Great Famine with data from the China Health and Retirement Longitudinal Study survey. Results show that female babies who were exposed in utero to the famine have higher diabetes risks, while male babies who were exposed to the Cultural Revolution are shown to have lower cognitive abilities.

Trends in inequality of opportunity in health over the life cycle: The role of early-life conditions.

This paper explores the evolution of inequality of opportunity in the prevalence of chronic diseases along the life cycle and across different birth cohorts for individuals aged 50 or older and residing in 13 European countries. We adopt an ex-ante parametric approach and rely on the dissimilarity index as our reference inequality metric. In addition to a commonly used set of circumstances, we pay particular attention to the role of adverse early-life conditions, such as the experience of harm and the quality of the relationship with parents. In order to quantify the relative importance of each circumstance, we apply the Shapley inequality decomposition method. Our results suggest that inequality of opportunity in health is not stable over the life cycle - it is generally lower at younger ages and then monotonically increases. Moreover, it varies between different birth cohorts and is generally higher for younger individuals than for older age groups. Finally, the contribution of adverse early life conditions ranges between 25% and 45%, which is comparable to the share of socio-economic circumstances but significantly higher than the relative contribution of other demographic characteristics, especially at younger ages.

Stressors interact across generations to influence offspring telomeres and survival.

Parental stress often has long-term consequences for offspring. However, the mechanisms underlying these effects and how they are shaped by conditions offspring subsequently experience are poorly understood. Telomeres, which often shorten in response to stress and predict longevity, may contribute to, and/or reflect these cross-generational effects. Traditionally, parental stress is expected to have negative effects on offspring telomeres, but experimental studies in captive animals suggest that these effects may depend on the subsequent conditions that offspring experience. Yet, the degree to which parental stress influences and interacts with stress experienced by offspring to affect offspring telomeres and survival in free-living organisms is unknown. To assess this, we experimentally manipulated the stress exposure of free-living parent and offspring house sparrows (Passer domesticus). We found a weak, initial, negative effect of parental stress on offspring telomeres, but this effect was no longer evident at the end of post-natal development. Instead, the effects of parental stress depended on the natural sources of stress that offspring experienced during post-natal development whereby some outcomes were improved under more stressful rearing conditions. Thus, the effects of parental stress on offspring telomeres and survival are context-dependent and may involve compensatory mechanisms of potential benefit under some circumstances.

Reproductive Strategies Affect Telomere Dynamics across the Life Course.

AbstractBecause parental care has a heritable basis, the benefits of receiving increased parental provisioning early in life are genetically linked to the costs of providing increased parental provisioning at adulthood. Reproductive strategies thus result in distinct cost-benefit syndromes across the life course that may shape individual health and aging trajectories. Here we used an artificial selection approach in Japanese quail (Coturnix japonica) to test how reproductive strategies affect telomere length, a biomarker of somatic state, at different life stages. We show that males but not females from lines selected for low maternal investment (i.e., developing in a relatively small egg) had shorter telomeres at birth. These patterns were still weakly present at the end of the juvenile growth period. In contrast, significantly shorter telomeres were found in reproductively active adult birds from the high-investment lines, suggesting that telomere attrition was accelerated in these individuals once they had become reproductively active. Our study shows that reproductive strategies differentially affect telomere dynamics across the life course, highlighting the role of cross-generational constraints in shaping individual aging trajectories.

Childhood Socioeconomic Disadvantage and Pathways to Memory Performance in Mid to Late Adulthood: What Matters Most?

OBJECTIVES: Childhood socioeconomic disadvantage is consistently associated with lower cognitive function in later life. This study aims to distinguish the contribution of specific aspects of childhood socioeconomic disadvantage for memory performance in mid to late adulthood, with consideration for direct and indirect effects through education and occupation. METHODS: Data were from adults aged 50 to 80 years who completed the life history module in the 2006/2007 wave of the English Longitudinal Study of Aging (n = 4,553). The outcome, memory score, was based on word recall tests (range: 0-20 points). We used the g-formula to estimate direct and indirect effects of a composite variable for childhood socioeconomic disadvantage and its 4 individual components: lower-skilled occupation of the primary breadwinner, having few books in the home, overcrowding in the home, and lack of water and heating facilities in the home. RESULTS: Few books were the most consequential component of childhood socioeconomic disadvantage for later-life memory (total effect: -0.82 points for few books; 95% confidence interval [CI]: -1.04, -0.60), with roughly half being a direct effect. The total effect of a breadwinner in lower-skilled occupations was smaller but not significantly different from a few books (-0.67 points; 95% CI: -0.88, -0.46), while it was significantly smaller with overcrowding (-0.31 points; 95% CI: -0.56, -0.06). The latter 2 total effects were mostly mediated by education and occupation. DISCUSSION: A literate environment in the childhood home may have lasting direct effects on memory function in mid to later life, while parental occupation and overcrowding appear to influence memory primarily through educational and occupational pathways.

Rising childhood income inequality and declining Americans' health.

Morbidity and mortality are on the rise among Baby Boomers and younger cohorts. This study investigates whether this unfavorable health trend across birth cohorts 1925-1999 is related to rising income inequality Americans face during childhood. We use two nationally representative datasets: National Health and Nutrition Examination Surveys (NHANES) 1988-2018 and Panel Studies of Income Dynamics (PSID) 1968-2013, and two health outcomes: biomarkers of physiological dysregulation, and a chronic disease index. Childhood income inequality is measured by the average of the Gini index at the national level each birth cohort is exposed to between birth and age 18, where the Gini index from 1925 to 2016 is computed based on Internal Revenue Service income data. By merging childhood income inequality to individual level data from NHANES or PSID based on birth cohort, we find childhood income inequality is positively associated with the risk of physiological dysregulation in adulthood for all gender and racial groups in the NHANES data. It is also significantly related to the risk of chronic disease in the PSID data. This association is robust to controls for individual level childhood health and family background, adulthood socioeconomic and marital status, and contemporary macro socioeconomic factors. More importantly, childhood income inequality exposure explains a substantial amount of variation in these two health outcomes across cohorts, a pattern not observed for other early life exposures that display negative temporal trends similar to those for childhood income inequality. This study provides important evidence that income inequality experienced during childhood may have a long-lasting negative consequence for adult health, which partially explains the adverse health trends experienced by Baby Boomers and younger cohorts in the United States.

Fitness Changes in Adolescent Girls Following In-School Combined Aerobic and Resistance Exercise: Interaction With Birthweight.

PURPOSE: To assess the efficacy of a supervised in-school combined resistance and aerobic training program in adolescent girls and investigate whether responses differ according to birthweight. METHODS: Participants (girls aged 13-17 y) were randomized either to an intervention replacing physical education (PE) classes with 2 × 60-minute training sessions per week (n = 58) or to a control group that continued to attend 2 × 60 minutes per week of curriculum PE (n = 41). We measured muscular fitness (handgrip, standing long jump, and sit-ups), cardiorespiratory fitness (20-m shuttle run), skinfolds, and lean body mass preintervention and postintervention and determined effect size (Hedge's g) differences between changes in these measures. We also compared changes within lower (<3000 g) and normal birthweight intervention and PE control subgroups. RESULTS: The intervention group showed greater improvements in all the fitness measures and lean body mass (g = 0.22-0.48) and lower skinfold increases (g = 0.41) than PE controls. Within the intervention group, improvements in all fitness measures were larger in lower birthweight (g = 0.53-0.94) than in normal birthweight girls (g = 0.02-0.39). CONCLUSION: Replacing curriculum PE with supervised training improved muscular and cardiorespiratory fitness and body composition outcomes in adolescent females. Our findings suggest an enhanced adaptive response to training in participants with lower birthweight which warrants further investigation.

Life-Course Transitions in Rural Residence and Old-Age Mortality in Iowa, 1930-2014.

Early-life conditions are associated with mortality in men, but not studied to the same extent in women. We add new evidence by studying a cohort of women born between 1916 and 1931 and followed for mortality between 1986 and 2013. Our sample from Iowa includes a significant number of rural women, from both farms and small towns. The long-term effects of growing up in a rural area were mixed: farmers' daughters lived longer than women growing up off-farm in rural areas. Daughters of farm laborers and skilled or semi-skilled trades workers fared worst, when considering early-life socioeconomic status. We also find evidence that migrating to small-town Iowa was associated with lower life expectancy after age fifty-five. Considering social class and farm-nonfarm status is important for understanding the health of rural America.

Unstable Childhood, Adult Adversity, and Smoking Accelerate Biological Aging Among Middle-Age African Americans: Similar Findings for GrimAge and PoAm.

Objectives: The recent biological clocks GrimAge and PoAm are robust predictors of morbidity and mortality. Little research, however, has investigated the factors that influence their ticking speed. No study has used multivariate analyses to examine whether childhood adversity, adult hardship, lifestyle practices, or some combination of these factors best explains acceleration of these indices. Methods: Using a sample of 506 middle-age African Americans, the present study investigated the extent to which childhood instability, adult adversity, and lifestyle predict accelerated GrimAge and PoAm. Results: The two clocks were highly correlated and the pattern of findings was very similar for the two measures. Childhood instability, adult financial hardship, and smoking were significant predictors of both clocks. Discussion: The findings support a life course perspective where both the long arm of childhood as well as later life conditions influence speed of aging. Similar results across the two clocks enhance confidence in the findings.

Direct and indirect associations between childhood socioeconomic status and cognitive function in the middle-aged and older adults in China.

OBJECTIVES: To investigate whether childhood socioeconomic status (SES) is associated with cognitive function, and what factors might mediate the associations. METHOD: Using data from the China Health and Retirement Longitudinal Study (CHARLS) and within frameworks of the latency model, the pathway model and the accumulation model, we quantified direct and indirect pathways between childhood SES and cognitive function for Chinese middle-aged and older adults aged 45+ by structural equations modeling. RESULTS: We found significant direct, indirect and total effects of childhood SES on cognitive function at baseline. The indirect effects were mediated through educational attainment, household consumption, smoking behaviors and social engagement. At follow-ups, cognitive enhancement can be made by indirect pathways through educational attainment, improvement of household consumption and social engagement. CONCLUSION: Our results supported the latency model, the pathway model and the accumulation model when considering pathways linking childhood SES to cognitive function. The findings underscored the value of taking early interventions to improve SES and cognitive function, especially among those with low childhood SES.

Impact of Early Life Socioeconomic Status on Decision Making in Older Adults Without Dementia.

OBJECTIVES: A growing body of evidence points to the negative impact of early life socioeconomic status (SES) on health and cognitive outcomes in later life. However, the effect of early life SES on decision making in old age is not well understood. This study investigated the association of early life SES with decision making in a large community-based cohort of older adults without dementia from the Rush Memory and Aging Project. MATERIALS AND METHODS: Cross-sectional data from the Rush Alzheimer's Disease Center Memory and Aging Project was analyzed. Participants were 1044 community-dwelling older adults without dementia (M age = 81.15, SD = 7.49; 75.8% female; 5.4% non-White). Measures of financial and healthcare decision making and early life SES were collected, along with demographics, global cognition, and financial and health literacy. RESULTS: Early life SES was positively associated with decision making (estimate = 0.218, p = 0.027), after adjustments for demographic covariates and global cognition, such that a one-unit increase in early life SES was equivalent to the effect of being four years younger in age as it pertains to decision making. A subsequent model demonstrated that the relationship was strongest in those with low literacy, and weakest for those with high literacy (estimate = -0.013, p = 0.029). CONCLUSIONS: Findings from this study suggest that early life SES is associated with late life decision making and that improving literacy, a modifiable target for intervention, may buffer the negative impact of low early life SES on decision making in older adulthood.

Height and quality of life among older adults (50+) in India: a cross-sectional study.

Adult height is a summary measure of health and net nutrition in early childhood. This study examines the association between height and quality-of-life outcomes in older adults (50+) in India. Cross-sectional data from Wave 1 of the World Health Organization (WHO) Study on global AGEing and adult health (SAGE) conducted in 2007 were analysed. The association between height and quality of life was assessed using bivariate and multivariate logistic and linear regression models. The mean WHO quality-of-life score (WHO-QoL) increased from 45.2 among the older adults in the lowest height quintile to 53.2 for those in the highest height quintile. However, the prevalence of self-rated poor quality of life declined from 16.4% in the lowest height quintile to 6.1% in the highest height quintile. In the fully adjusted regression model, height was found to be positively associated with quality-of-life outcomes among both men and women, independent of socioeconomic and physical health confounders. The association was particularly strong for women. Women in the highest height quintile had a 2.65 point higher WHO-QoL score than those in the lowest height quintile. Similarly, the likelihood of reporting a poor quality of life was lower among women in the highest height quintile. Furthermore, measures of economic status, handgrip strength, cognitive ability and poor self-rated health were significantly associated with WHO-QoL and self-rated poor quality of life. Overall, this study revealed a significant association between height and quality of life among older adults in India, suggesting a significant role of childhood circumstances in quality of life in later life.

Subjective socioeconomic status, health, and early-life conditions.

We study the role of subjective social status on health and its correlates, with an emphasis on the predictive power of early-life conditions on subjective social status. A well-established literature links early-life conditions to later-life objective measures of socioeconomic status, but little attention has been paid to their effects on subjective socioeconomic status. We find that socioeconomic factors during childhood are important predictors of subjective social status, even after controlling for contemporaneous socioeconomic conditions. This shows an additional psychological and behavioral channel through which early-life conditions influence later outcomes and which has not been yet studied in sufficient detail.

Extreme weather and mortality: Evidence from two millennia of Chinese elites.

Modern technology empowers human beings to cope with various extreme weather events. Using Chinese historical data, we examine the impact of extreme weather on long-term human mortality in an environment where individuals had no access to modern technology. By combining life-course data on 5000 Chinese elites with historical weather data over the period 1-1840 AD, we find a significant and robust negative impact of droughts in childhood on the longevity of elites. Quantitatively, encountering three years of droughts in childhood reduces an elite's life span by about two years.

Silver-spoon upbringing improves early-life fitness but promotes reproductive ageing in a wild bird.

Early-life conditions can have long-lasting effects and organisms that experience a poor start in life are often expected to age at a faster rate. Alternatively, individuals raised in high-quality environments can overinvest in early-reproduction resulting in rapid ageing. Here we use a long-term experimental manipulation of early-life conditions in a natural population of collared flycatchers (Ficedula albicollis), to show that females raised in a low-competition environment (artificially reduced broods) have higher early-life reproduction but lower late-life reproduction than females raised in high-competition environment (artificially increased broods). Reproductive success of high-competition females peaked in late-life, when low-competition females were already in steep reproductive decline and suffered from a higher mortality rate. Our results demonstrate that 'silver-spoon' natal conditions increase female early-life performance at the cost of faster reproductive ageing and increased late-life mortality. These findings demonstrate experimentally that natal environment shapes individual variation in reproductive and actuarial ageing in nature.