Effects Of Early Life Conditions Research Articles

Vestiges of famine: Long-term mortality impacts of early-life exposure to the 1840s famine in Estonia

The paper investigates whether exposure to a famine in the Russian Tsarist Province of Livland in 1844–1846 in early life negatively affected survival at later ages, using individual data from two rural parishes. We follow 18 birth cohorts born between 1834–1852 until age 75 and differentiate between timing and length of exposures. We find that relative to individuals born in pre- or post- crisis years, there were no significant differences in survival from age 21–75. Cohorts with longer exposure to famine conditions had increased mortality only in short term, up to age 20. Males were more vulnerable in younger ages than females. The negative effect of adverse early life exposure on survival in later life was constrained to lower social group – the landless, but for the better-off groups the effect was constrained to younger ages. The paper highlights the importance of accounting for sex and socio-economic differences in studies exploring the effects of early life conditions on later-life survival.

ECR Spotlight – Alexander Hansson

ECR Spotlight is a series of interviews with early-career authors from a selection of papers published in Journal of Experimental Biology and aims to promote not only the diversity of early-career researchers (ECRs) working in experimental biology during our centenary year but also the huge variety of animals and physiological systems that are essential for the ‘comparative’ approach. Alexander Hansson is an author on ‘ Sex and early-life conditions shape telomere dynamics in an ectotherm’, published in JEB. Alexander conducted the research described in this article while a PhD student in Mats Olsson's lab at the University of Gothenburg, Sweden, and Erik Wapstra's lab at the University of Tasmania, Australia. He has a particular interest in the effects of early-life conditions on telomere dynamics and life history traits in ectotherms.

Effects of early-life conditions on innate immune function in adult zebra finches.

ABSTRACTEarly life conditions can affect individuals for life, with harsh developmental conditions resulting in lower fitness, but the underlying mechanisms are not well understood. We hypothesized that immune function may be part of the underlying mechanism, when harsh developmental conditions result in less effective immune function. We tested this hypothesis by comparing innate immune function between zebra finches (Taeniopygia guttata) in adulthood (n=230; age 108–749 days) that were reared in either small or large broods. We used this experimental background to follow up our earlier finding that finches reared in large broods have a shorter lifespan. To render a broad overview of innate immune function, we used an array of six measures: bacterial killing capacity, hemagglutination, hemolysis, haptoglobin, nitric oxide and ovotransferrin. We found no convincing evidence for effects of natal brood size on any of the six measures of innate immune function. This raised the question whether the origin of variation in immune function was genetic, and we therefore estimated heritabilities using animal models. However, we found heritability estimates to be low (range 0.04–0.11) for all measured immune variables, suggesting variation in innate immune function can largely be attributed to environmental effects independent of early-life conditions as modified by natal brood size.

Experimental simulations of climate change induced mismatch in oak and larval development rates impact indicators of fitness in a declining woodland moth

Consequences of climate change‐driven shifts in the relative timing of spring activities of interacting species are insufficiently understood, especially for insects. We use a controlled experiment which simulates a trophic mismatch scenario in which lepidopteran larvae predominately feed on older leaves due to foliage developing faster than larvae growth rates. As a case study our experiment uses Orthosia cerasi, which is a widespread but declining woodland moth whose UK declines appear to be driven by warming temperatures. In the control experiment larvae are fed young oak Quercus robur leaves (bud burst stages six and seven), whilst in the treatment newly emerged larvae are fed young leaves but then gradually transition to feed on older leaves (post bud burst stage seven). We assess impacts on duration of the larval stage, pupal size and overwintering duration and survival. Larvae in the phenological mismatch treatment had a longer larval period, and smaller and lighter pupae. Larval diet did not carry over to influence emergence dates as earlier pupation of control larvae was balanced by an equivalent increase in the duration of the pupal stage. Increased time spent as larvae could increase predation rates from avian predators, whilst slowing the seasonal decline in food availability for those bird species. Reduced pupal size and weight are indicators of lower fecundity in emerging adults. Notably, we find that adults emerging from the mismatch treatment exhibited greater rates of abnormal vestigial wing development, which is likely to further reduce fitness. Trophic mismatches in which caterpillars have reduced availability of young leaves may thus contribute to the population declines observed in many woodland moth species due to increased mortality at larval stages, and adverse effects of early life conditions that reduce the reproductive success of emerging adults.

Effects of maternal exposure to a bacterial antigen and altered post-hatching rearing conditions on avian offspring behaviour

The early-life environment plays a crucial role in shaping morphological, physiological, and behavioural traits, with potential long-term consequences for fitness. Indeed, a set of factors experienced by offspring during prenatal and early post-natal development has been recognised to affect behavioural trait expression in later life. Several studies have shown that in birds, nutritional and social rearing conditions and maternal and/or neonatal immunisations may profoundly determine the development and establishment of behaviour in offspring. To our knowledge, no research has examined whether and how the interaction between immune-mediated maternal effects and post-hatching rearing conditions affects offspring behaviour. Here, we studied the effects of maternal exposure to a bacterial antigen and altered brood size on docility, breathing rate, and aggression in the offspring of great tit, Parus major. We used a 2 × 2 design to investigate the interactive effects of maternal immunisation and brood size manipulation on offspring behavioural development. We found no such interactive effect on offspring behaviour, although we observed it regarding to offspring body mass and tarsus length. Maternal immunisation itself did not affect offspring behaviour. However, we demonstrated that the offspring breathing rate and level of aggression were affected by brood size manipulation. Both breathing rate and aggression in offspring reared in enlarged broods were lower than those in offspring reared in non-manipulated broods. Our study did not confirm earlier reports that immune-mediated maternal effects modulate offspring behavioural development, but we showed that brood size during rearing might indeed be a factor that affects offspring behaviour.Significance statementThe early environment experienced by offspring constitutes a significant source of developmental plasticity, which may profoundly affect the establishment of their behavioural traits. Food availability, social conditions, and maternal or offspring infection are crucial factors shaping various behavioural traits in birds. However, there remains a lack of studies emphasising the potential interactive effects of early-life conditions on behavioural trait development in natural bird populations. Here, to our knowledge for the first time, we experimentally examined how maternal immunisation and altered post-hatching rearing conditions interact to determine the behaviour of fledged offspring. We found that maternal treatment and brood size manipulation interactively affected offspring body mass and tarsus length, but this interaction had no effect on offspring behaviour. Our findings suggest that different mechanisms may underlie the development of morphological and behavioural traits.

Association between childhood socioeconomic status and subjective memory complaints among older adults: results from the Japan Gerontological Evaluation Study 2010.

Subjective memory complaints (SMC) have been suggested as an early marker of mild cognitive impairment and dementia. However, there is a paucity of evidence on the effects of early life conditions on the development of SMC in old age. This study is aimed at investigating the association between childhood socioeconomic status (SES) and SMC in community-dwelling older adults. We used the data of the Japan Gerontological Evaluation Study, a population-based cohort study of people aged 65 years or older enrolled from 28 municipalities across Japan. Childhood SES and SMC in everyday life were assessed from the self-report questionnaire administered in 2010 (n = 16,184). Poisson regression was performed to determine their association, adjusted for potential confounders and life-course mediators and examined cohort effects. We identified SMC in 47.4% of the participants. After adjusting for sex, age, and number of siblings, low and middle childhood SES were associated with 29% (prevalence ratio [PR]: 1.29, 95% confidence interval [CI]: 1.22, 1.36) and 10% higher prevalence of SMC (PR: 1.10, 95%CI: 1.04, 1.17), respectively, compared with high childhood SES (p for trend <.001). The interaction terms between childhood SES and age groups were not statistically significant. Childhood SES is significantly associated with SMC among community-dwelling older adults. Efforts to minimize childhood poverty may diminish or delay the onset of SMC and dementia in later life.

The effect of early life conditions on song traits in male dippers (Cinclus cinclus).

Song complexity and singing frequency in male birds are shaped by female choice; they signal male quality because song is costly to develop and produce. The timing of song learning and the development of the brain structures involved occur during a period when chicks are exposed to a number of potential stressors. The quality and quantity of song produced by adults may therefore reflect the level of stress experienced during early life, a theory known as the ‘developmental stress hypothesis’. We tested this hypothesis using song recordings and life-history data from an individually marked, long-term study population of wild dippers (Cinclus cinclus). The extent to which early life conditions predict adult song traits was investigated using natal brood size as a measure of sibling competition; the rate of provisioning by parents as a proxy for nutritional stress; and residuals of the linear regression between body mass and tarsus length as a measure of nestling condition. The syllable diversity in the songs of adult males was positively correlated with their body condition as nestlings, but there was no significant correlation with either provisioning rate or brood size. Provisioning rate did, however, predict song rate; males in relatively poor condition as nestlings or those raised in smaller broods which were fed more frequently by their parents sang at a higher rate in adulthood. These results support the developmental stress hypothesis and provide some of the first evidence from a wild bird of how the conditions experienced during early life impact adult song. Song traits may therefore provide females with information regarding both the current condition and developmental history of males.

When the Census Comes Marching In: Challenges and Successes in Linking Individual-Level Census Records to the Utah Population Database

IntroductionThe availability of historic, individual-level census records in the United States has grown in recent years. With access to identifiers, it is possible to link these records to existing databases. The performance of and strategy for these linking efforts is not well characterized.&#x0D; Objectives and ApproachThe Utah Population Database (UPDB), launched in 1975, is a population registry comprising comprehensive data from genealogies, medical/vital records, and numerous administrative and demographic records spanning the past two centuries. UPDB initially did not hold individual-level US Census records until now. UPDB has massive volumes of identifiers that we have cleaned and it therefore represents a “gold standard” representation of Utah’s population. The objective here is to describe the methods used and the record linking performance applied to census records that we have linked to the UPDB for persons appearing in the 1880, 1900, 1910, 1920, 1930 and 1940 censuses.&#x0D; ResultsWe collaborated with FamilyTree, Ancestry, and IPUMS (University of Minnesota) for keying and preparing data from the 1880-1940 censuses. We then linked these records to the UPDB using probabilistic record linking methods and manual review. Linking rates by census year varied by the quality of records and electronic data capture and by specific Census fields for a given census. Data quality was somewhat lower for the 1910 and 1940 censuses and hence they had lower linking rates (66.9% and 70.4, respectively). Household heads enjoyed higher linking rates (72% was the lowest, in 1940). We used household heads to help guide links to offspring and spouses whose linking rates exceeded 75% in general. Non-family members and single men linked at much lower rates (&lt;50%).&#x0D; Conclusion/ImplicationsThis study found that linking census records to an existing population registry is feasible and with relative success. Using household/genealogy structure of the census is useful when linking to the genealogies in the UPDB. These links allow studies of effects of early life conditions on later life outcomes.

Early Life Displacement Due to Armed Conflict and Violence, Early Nutrition, and Older Adult Hypertension, Diabetes, and Obesity in the Middle-Income Country of Colombia.

Objective: We examine the importance of early life displacement and nutrition on hypertension (HTN) and diabetes in older Colombian adults (60+ years) exposed to rapid demographic, epidemiological, and nutritional transitions, and armed conflict. We compare early life nutritional status and adult health in other middle- and high-income countries. Method: In Colombia (Survey of Health, Wellbeing and Aging [SABE]-Bogotá), we estimate the effects of early life conditions (displacement due to armed conflict and violence, hunger, low height, and not born in the capital city) and obesity on adult health; we compare the effects of low height on adult health in Mexico, South Africa (Study on Global Ageing and Adult Health [SAGE]), the United States, and England (Health and Retirement Study [HRS], English Longitudinal Study of Ageing [ELSA]). Results: Early life displacement, early poor nutrition, and adult obesity increase the risk of HTN and diabetes in Colombia. Being short is most detrimental for HTN in Colombian males. Discussion: Colombian data provide new evidence into how early life conditions and adult obesity contribute to older adult health.

Early Childhood Conditions and Old-Age Mortality

Background:Early life conditions might determine adult mortality. The literature, however, both support and contradict this proposition. In most studies, the outcome has been the mortality rates in a given period of time. These rates represent the combined result of both previous and current exposures. Therefore, it is more apt to study the rate of improvement as an outcome, rather than mortality rates in a given period of time.Objective:The effects of early-life conditions, assessed as mortality rates at ages 0 and 1-4, and the effects of indicators of available resources in adult life were analysed.Methods:The outcomes were the decrease in the national rates of mortality in three age groups, aged 24-34, 35-54 and 55-74, in 18 OECD countries over the years 1990-2010. The effects were analysed in linear multiple regression models using least squares, controlling for country-specific historical constants, which represent the mortality rates in 1990.Results:Among the 24-34 and 35-54 year-olds, neither early-life indicators nor resource indicators significantly affected the regression equations. Among the 55-74 year-olds, however, in the model including the mortality rate at age 0 in 1940-49, the explanatory value of the equation in question increased from 65 to 79%, and the effect of mortality rate at age 0 was statistically significant.Conclusion:Significant effects of early-life conditions on the rate of decrease in mortality were found, but only in the oldest age group. This finding is consistent with Gavrilov’s reliability theory of aging.Key Points• Mortality rates have decreased almost linearly in recent decades in OECD countries.• Most of the variation between countries seemed to be determined by past history and the catch-up of nations that have previously lagged behind.• A significant effect of early-life conditions on the rate of decrease in mortality was found, but only in the 55-74 year-olds, not in the 24-34 and 35-54 year-olds.

CHILDHOOD SOCIOECONOMIC STATUS AND ADULT ISCHEMIC HEART DISEASE: A LIFE COURSE PATHWAY MODEL OF HEALTH

There is a well-established relationship between childhood socioeconomic status (SES) and adult health, but how early-life conditions are able to influence health and aging in later-life is less clear. To elucidate this process, this study investigated how childhood SES influences ischemic heart disease (IHD)—a common disease among older adults—through multiple paths of adult health lifestyles, SES, and chronic inflammation. Guided by two interdisciplinary life course perspectives, this study hypothesized that socioeconomic disadvantage during childhood would lead to unhealthy lifestyles and lower SES in adulthood, which would lead to chronic inflammation that would subsequently raise the risk of IHD. Data came from six waves of the Health and Retirement Study between 2004 and 2014, comprising a sample of 11,697 U.S. men and women aged 51 and older. A series of Cox proportional hazards models examined the relationship between childhood SES and adult IHD. Statistical tests of mediation were conducted to determine whether adult health lifestyles, SES, and chronic inflammation mediated the relationship between childhood SES and adult IHD. Findings revealed that lower childhood SES raised IHD risk by directly impacting adult health lifestyles and SES, which subsequently led to higher levels of systemic inflammation, resulting in onset of IHD. These findings clarify how childhood SES impacts health among older adults. Using multiple mediating domains to assess the long-term effects of early-life conditions can enhance U.S. health policy in an effort to reduce the associated disease burden of childhood SES.

Can environmental conditions experienced in early life influence future generations?

The consequences of early developmental conditions for performance in later life are now subjected to convergent interest from many different biological sub-disciplines. However, striking data, largely from the biomedical literature, show that environmental effects experienced even before conception can be transmissible to subsequent generations. Here, we review the growing evidence from natural systems for these cross-generational effects of early life conditions, showing that they can be generated by diverse environmental stressors, affect offspring in many ways and can be transmitted directly or indirectly by both parental lines for several generations. In doing so, we emphasize why early life might be so sensitive to the transmission of environmentally induced effects across generations. We also summarize recent theoretical advancements within the field of developmental plasticity, and discuss how parents might assemble different ‘internal’ and ‘external’ cues, even from the earliest stages of life, to instruct their investment decisions in offspring. In doing so, we provide a preliminary framework within the context of adaptive plasticity for understanding inter-generational phenomena that arise from early life conditions.

Lifelong consequences of early nutritional conditions on learning performance in zebra finches (Taeniopygia guttata)

Long-term effects of early developmental conditions on physiological and behavioural traits are common in animals. Yet, such lifelong effects of early life conditions on learning skills received relatively less attention, even though they are expected to have strong fitness effects. To test the lifelong impact of the early environment on associative and reversal learning performance, we tested zebra finches (Taeniopygia guttata) in a reversal learning task about five years after they were raised either under low or high quality food treatments in their first month of life. The early nutritional treatment and its respective growth patterns significantly influenced learning performance: Zebra finches who received a high-quality nutrition early in life gained more weight during the treatment period but needed more trials to associate a cue with a reward. The early growth rate during the treatment phase was linked to how fast the birds detected the food at the onset of training in our learning task as well as to their associative learning performance. However, in the reversal learning step of the task testing for behavioural flexibility, no differences with respect to early nutritional treatments or related growth rates were apparent. We show that early life conditions directly affect the approach to our task and learning abilities over an entire lifetime, emphasizing how crucial the early environment is for understanding adult behaviour throughout life.

Alpine ibex males grow large horns at no survival cost for most of their lifetime

Large horns or antlers require a high energy allocation to produce and carry both physiological and social reproductive costs. Following the principle of energy allocation that implies trade-offs among fitness components, growing large weapons early in life should thus reduce future growth and survival. Evidence for such costs is ambiguous, however, partly because individual heterogeneity can counterbalance trade-offs. Individuals with larger horns or antlers may be of better quality and thus have a greater capacity to survive. We investigated trade-offs between male early horn growth and future horn growth, baseline mortality, onset of actuarial senescence, and rate of ageing in an Alpine ibex (Capra ibex ibex) population. Horn growth of males in early life was positively correlated to their horn length throughout their entire life. Cohort variation and individual heterogeneity both accounted for among-individual variation in horn length, suggesting both long-lasting effects of early life conditions and individual-specific horn growth trajectories. Early horn growth did not influence annual survival until 12 years of age, indicating that males do not invest in horn growth at survival costs over most of their lifetime. However, males with fast-growing horns early in life tended to have lower survival at very old ages. Individual heterogeneity, along with the particular life-history tactic of male ibex (weak participation to the rut until an old age after which they burn out in high mating investment), are likely to explain why the expected trade-off between horn growth and survival does not show up, at least until very old ages.

Migration and health: a study of effects of early life experiences and current socio-economic situation on mortality of immigrants in Sweden

Objectives. Previous research has demonstrated mortality differences between immigrants and natives living in Sweden. The aim of this study is to investigate the effects of early life conditions in the country of birth and current socio-economic conditions in adult life in Sweden on cardiovascular, cancer, all other cause and total mortality among immigrants and natives in Sweden. Design. The cohort data concerning individual demographic characteristics and socio-economic conditions stems from the Swedish Longitudinal Immigrant Database (SLI), a register-based representative database, and consists of individuals from 11 countries of birth, born between 1921 and 1939, who were residents in Sweden between 1980 and 2001. The associations between current socio-economic conditions as well as infant mortality rates (IMR) and Gross Domestic Product (GDP) per capita in the year and country of birth, and total, cardiovascular, cancer and ‘all other’ mortality in 1980–2001 were calculated by survival analysis using Cox proportional hazards regression to calculate hazard rate ratios. Results. The effects of current adult life socio-economic conditions in Sweden on mortality are both stronger and more straightforward than the effects of early life conditions in the sense that higher socio-economic status is significantly associated with lower mortality in all groups of diagnoses; however, we find associations between infant mortality rates (IMR) in the year and country of birth, and cancer mortality among men and women in the final model. Conclusions. Socioeconomic conditions in Sweden are more strongly associated with mortality than early life indicators IMR and GDP per capita in the year of birth in the country of origin. This finding has health policy and other policy implications.

Fetal growth, early life circumstances, and risk of suicide in late adulthood

Recent studies in Sweden and Scotland have found early life conditions to be associated with increased risk of attempted and completed suicide in adolescence and young adulthood. It is not known, however, whether early life conditions affect suicide risk throughout the life course, from adulthood into old age. We examined the effects of early life conditions, including markers of fetal growth, and social and economic characteristics in adulthood, on risk of suicide by violent and non-violent methods in women and men aged 31-87 years using Cox regression. 11,650 women and men born at the Uppsala University Hospital in Sweden between 1915 and 1929 were followed from 1960 until 2002 using linked records from obstetric archives, Census, population and mortality registries. During 435,039 person-years of follow-up 161 completed suicides (104 in males, 57 in females) were observed. An inverse association was found between lower birthweight-for-gestational age and risk of violent suicide in females, although the association did not reach the conventional level of statistical significance (minimally adjusted HR 2.02, 95% CI (0.88-4.63); Table 4). Being male, unmarried, and in the "other or unknown" social class category in adulthood were independently associated with increased rates of suicide. There was a weak association between higher maternal parity and suicide rates. Our findings suggest differences in effects of fetal growth patterns and perinatal circumstances on suicide risk later in life, and suggest that suicide in adults and in the elderly may be influenced by a different combination of factors than those that influence suicide in adolescence and young adulthood.

Costs of compensation: effect of early life conditions and reproduction on flight performance in zebra finches

Conditions experienced in early life have been shown to affect the development or programming of physiological processes. While animals may recover from earlier periods of adversity, this process can carry long-term costs. Such long-term effects are likely to be most evident when individuals are placed in demanding situations that require high performance. Escape flight speed in passerine birds is crucial to predator evasion and requires very rapid take-off. Here, we examine whether the ability to maintain escape flight performance during the immediate post-breeding period is influenced by conditions in early life. We manipulated the early life conditions experienced by zebra finches (Taeniopygia guttata) by rearing them on either low or high quality food through the growth period, or by changing conditions halfway through the nestling period, moving from high to low or vice versa. While there was no difference amongst the treatment groups in body size attained by adulthood, amongst the birds that experienced low quality food, the body size of those that were switched to a high quality diet halfway through the nestling growth period recovered faster than those that had low quality food until fledging. We found no differences amongst the dietary groups in flight performance at adulthood prior to breeding, and all groups showed a decline in average escape flight performance over the breeding period. However, the magnitude of the post-breeding decline in flight performance for a given level of reproductive output was significantly greater for those females that had experienced a switch from a low to a high quality diet during the nestling phase. These results suggest that this diet-induced rapid recovery of body size, which may have immediate competitive advantages, nonetheless carries locomotory costs in later life manifest in the capacity to sustain the high performance escape response during the post-reproductive recovery phase.

Period and cohort effects on elderly mortality: a new relational model for smoothing mortality surfaces

This study investigates the relative importance of period and cohort effects in adult and elderly mortality in Italy and Sweden in the second half of the 20th century. For this purpose, we devised a two-dimensional semi-parametric model for mortality surfaces that produces good fit to the data and robust estimates of the period and cohort parameters. The findings of this study show that period effects have been of primary importance in the process of mortality reduction at adult and old ages observed in the last decades. The effects of early-life conditions are modest and often not statistically significant

From Angela's ashes to the Celtic tiger: Early life conditions and adult health in Ireland

We use data from the Irish census and exploit regional and temporal variation in infant mortality rates over the 20th century to examine effects of early life conditions on later life health. The urban mortality penalty collapsed in Ireland in the years right after World War II. Our main identification is public health interventions centered on improved sanitation and food safety, which we believed played a leading role in eliminating the Irish urban infant mortality penalty. Our estimates suggest that a unit decrease in mortality rates at time of birth reduces the probability of being disabled as an adult by about 12–18%.

Early life exposures and the occurrence and timing of heart disease among the older adult Puerto Rican population

Few studies have examined the effects of early life conditions on the timing of the onset of heart disease. We use the remarkable example of a representative sample of the population of older Puerto Ricans aged 60-74 who lived in the countryside during childhood (n = 1,438) to examine the effects ofseasonal exposures to poor nutrition and infectious diseases during late gestation on the timing of the onset and the probability of ever experiencing adult heart disease. Cox and log logistic hazard models controlling for childhood conditions (self-reported childhood health status and socioeconomic status [SES], rheumatic fever, and knee height) and adult risk factors (adult SES, obesity, smoking, exercise, and self-reported diabetes) showed that the risk of onset of heart disease was 65% higher among those born during high-exposure periods compared with unexposed individuals. However, there were no significant differences in median time of onset for those ever experiencing heart disease. As a comparison, we found that there were no significant seasonality effects for those who lived in urban areas during childhood. We conclude that early exposures in utero have important ramifications for adult heart disease among the older Puerto Rican population. We show, however, that while exposure is associated with the probability of ever experiencing adult heart disease, it is not associated with the timing of onset among those who do experience it.