Neighborhood Disadvantage, Greenness, and Population Density as Predictors of Breastfeeding Practices: A Population Cohort Study from Finland.

BACKGROUND: Many environmental factors are known to hinder breastfeeding, yet the role of the family living environment in this regard is still poorly understood. OBJECTIVES: We used data from a large cohort to identify associations between neighborhood characteristics and breastfeeding behavior. METHODS: Our observational study included 11,038 children (0-2 years) from the Southwest Finland Birth Cohort. Participant information was obtained from the Medical Birth Register and municipal follow-up clinics. Neighborhood socioeconomic disadvantage, greenness, and population density were measured for a period of 5 years prior to childbirth within the residential neighborhood on a 250 × 250-m grid. Any breastfeeding and breastfeeding at 6 months were the primary outcomes. Binary logistic regression models were adjusted for maternal health and socioeconomic factors. RESULTS: Adjusted analyses suggest that mothers living in less populated areas were less likely to display any breastfeeding (OR: 0.46; 95% CI: 0.36, 0.59) and breastfeeding at 6 months (OR: 0.37; 95% CI: 0.34, 0.40). Mothers living in highly disadvantaged neighborhoods were less likely to display any breastfeeding if the neighborhood was less populated (OR: 0.54; 95% CI: 0.30, 0.95) but more likely to breastfeed at 6 months if the neighborhood was highly populated (OR: 3.74; 95% CI: 1.92, 7.29). Low greenness was associated with higher likelihood of any breastfeeding (OR: 3.82; 95% CI: 1.53, 9.55) and breastfeeding at 6 months (OR: 4.41; 95% CI: 3.44, 5). CONCLUSIONS: Our results suggest that neighborhood characteristics are associated with breastfeeding behavior in Finland. Unravelling breastfeeding decisions linked to the living environment could help identify interventions that will allow the appropriate support for all mothers and infants across different environmental challenges.

Sex-specific links between the social landscape and faecal glucocorticoid metabolites in semi-captive Asian elephants.

Although social behaviour is common in group-living mammals, our understanding of its mechanisms in long-lived animals is largely based on studies in human and non-human primates. There are health and fitness benefits associated with strong social ties, including increased life span, reproductive success, and lower disease risk, which are attributed to the proximate effects of lowered circulating glucocorticoid hormones. However, to deepen our understanding of health-social dynamics, we must explore species beyond the primate order. Here, using Asian elephants as a model species, we combine social data generated from semi-captive timber elephants in Myanmar with measurements of faecal glucocorticoid metabolite (FGM) concentrations. These data enable a "natural experiment" because individuals live in work groups with different demographic compositions. We examine sex-specific FGM concentrations for four different aspects of an individuals' social world: general sociality, work group size, sex ratio and the presence of immatures (<5 years) within the work group. Males experienced lower FGM concentrations when engaged in more social behaviours and residing in female-biased work groups. Surprisingly, females only exhibited lower FGM concentrations when residing with calves. Together, our findings highlight the importance of sociality on individual physiological function among elephants, which may have broad implications for the benefits of social interactions among mammals.

Diet quality in preschool children and associations with individual eating behavior and neighborhood socioeconomic disadvantage. The STEPS Study.

A good quality diet in childhood is important for optimal growth as well as for long-term health. It is not well established how eating behaviors affect overall diet quality in childhood. Moreover, very few studies have considered the association of diet quality and a neighborhood socioeconomic disadvantage in childhood. Our aim was to investigate how diet quality is associated with eating behaviors and neighborhood disadvantage and their interaction in preschool age children in Finland. The participants were from the Steps to Healthy Development Study at age 2 y (n = 780) and 5 y (n = 653). Diet quality was measured with a short questionnaire on habitual food consumption and eating behavior was assessed with the child eating behavior questionnaire to indicate the child's eating style regarding food approach and food avoidance dimensions. Information on neighborhood socioeconomic disadvantage were obtained from the statistics Finland grid database. We found that diet quality was higher at 5 years compared to 2 years of age (p < 0.001). Food approach subscale, enjoyment of food, was positively associated with the diet quality (p < 0.001 for 2 and 5 y) while subscale desire to drink was negatively associated with the diet quality (p = 0.001 for 2 and 5 y). Food avoidance was negatively associated with the diet quality both at 2 and at 5 years of age (p < 0.001). A higher neighborhood disadvantage was negatively associated with the diet quality at the age of 2 years (p = 0.02), but not at the age of 5 years. Eating behavior had similar associations with diet quality both in affluent and deprived neighborhoods. Our results suggest that both the eating behavior and neighborhood disadvantage are, already in the early age, important factors when considering children's diet quality.

The elephant in the family: Costs and benefits of elder siblings on younger offspring life-history trajectory in a matrilineal mammal.

Many mammals grow up with siblings, and interactions between them can influence offspring phenotype and fitness. Among these interactions, sibling competition between different-age offspring should lead to reproductive and survival costs on the younger sibling, while sibling cooperation should improve younger sibling's reproductive potential and survival. However, little is known about the consequences of sibling effects on younger offspring life-history trajectory, especially in long-lived mammals. We take advantage of a large, multigenerational demographic dataset from semi-captive Asian elephants to investigate how the presence and sex of elder siblings influence the sex, survival until 5 years old, body condition, reproductive success (i.e. age at first reproduction and lifetime reproductive success) and long-term survival of subsequent offspring. We find that elder siblings have heterogeneous effects on subsequent offspring life-history traits depending on their presence, their sex and the sex of the subsequent offspring (named focal calf). Overall, the presence of an elder sibling (either sex) strongly increased focal calf long-term survival (either sex) compared to sibling absence. However, elder sisters had higher impact on the focal sibling than elder brothers. Focal females born after a female display higher long-term survival, and decreased age at first reproduction when raised together with an elder sister rather than a brother. Focal males born after a female rather than a male showed lower survival but higher body weight when both were raised together. We did not detect any sibling effects on the sex of the focal calf sex, survival until 5 years old and lifetime reproductive success. Our results highlight the general complexity of sibling effects, but broadly that elder siblings can influence the life-history trajectory of subsequent offspring. We also stress the importance of considering all life stages when evaluating sibling effects on life trajectories.

Denombreux mammifères grandissent en fratrie, et les interactions au sein de lafratrie peuvent influencer le phénotype et la valeur sélective des jeunes.Parmi ces interactions, la compétition entre frères et sœurs d'âges différentspeut entraîner des coûts de reproduction et de survie pour le/la plus jeune,tandis que les interactions coopératives améliorent la reproduction et lasurvie du/de la plus jeune. Cependant, nous avons encore peu de connaissancessur l'influence de la fratrie sur la trajectoire de vie des frères et sœursplus jeunes, en particulier chez les mammifères longévifs. Grâce àun jeu de données démographique multigénérationnel d'éléphants d'Asiesemi-captifs, nous avons pu étudier comment la présence d'un frère aînéou d'une sœur aînée influence le sexe, la survie jusqu'à l'âge de cinqans, la masse corporelle, la reproduction (i.e. l'âge de première reproductionet le succès reproductif sur toute la vie) et la survie à long terme du jeunesuivant. Nousobservons que les frères et sœurs aînés ont des effets hétérogènes sur lestraits d'histoire de vie du jeune suivant et ce, en fonction de leur présence,et du sexe du jeune suivant (appelé focal). Dansl'ensemble, la présence d'un frère aîné oud'une sœur aînée augmente fortement la survie à long terme du jeune focal parrapport à leur absence. Cependant, il est à noter que les sœurs aînées ont unimpact plus important que les frères ainés sur le frère focal. Les femellesfocales présentent une survie à long terme plus élevée et un âge de premièrereproduction plus précoce lorsqu'elles sont élevées avec une sœur aînée plutôtqu'un frère. Les mâles focaux élevés avec une grande sœur plutôt qu'un grandfrère présentent une survie plus faible mais un poids corporel plus élevé. Nousn'avons détecté aucun effet des frères aînés ou sœurs aînées sur le sexe, la survie jusqu'àl'âge de cinq ans et le succès reproducteur sur toute la vie du jeune focal. Nosrésultats mettent en évidence la complexité des effets de la fratrie et, lefait que les frères et sœurs plus âgés peuvent influencer la trajectoire ducycle de vie des jeunes suivant. Nous soulignons également l'importance deconsidérer toutes les étapes de la vie lors de l'évaluation des effets de lafratrie sur les trajectoires de vie.

Asian elephants exhibit post-reproductive lifespans.

BACKGROUND: The existence of extended post-reproductive lifespan is an evolutionary puzzle, and its taxonomic prevalence is debated. One way of measuring post-reproductive life is with post-reproductive representation, the proportion of adult years lived by females after cessation of reproduction. Analyses of post-reproductive representation in mammals have claimed that only humans and some toothed whale species exhibit extended post-reproductive life, but there are suggestions of a post-reproductive stage for false killer whales and Asian elephants. Here, we investigate the presence of post-reproductive lifespan in Asian elephants using an extended demographic dataset collected from semi-captive timber elephants in Myanmar. Furthermore, we investigate the sensitivity of post-reproductive representation values to availability of long-term data over 50 years. RESULTS: We find support for the presence of an extended post-reproductive stage in Asian elephants, and that post-reproductive representation and its underlying demographic rates depend on the length of study period in a long-lived animal. CONCLUSIONS: The extended post-reproductive lifespan is unlikely due to physiological reproductive cessation, and may instead be driven by mating preferences or condition-dependent fertility. Our results also show that it is crucial to revisit such population measures in long-lived species as more data is collected, and if the typical lifespan of the species exceeds the initial study period.

Capture from the wild has long-term costs on reproductive success in Asian elephants.

Capturing wild animals is common for conservation, economic or research purposes. Understanding how capture itself affects lifetime fitness measures is often difficult because wild and captive populations live in very different environments and there is a need for long-term life-history data. Here, we show how wild capture influences reproduction in 2685 female Asian elephants (Elephas maximus) used in the timber industry in Myanmar. Wild-caught females demonstrated a consistent reduction in breeding success relative to captive-born females, with significantly lower lifetime reproduction probabilities, lower breeding probabilities at peak reproductive ages and a later age of first reproduction. Furthermore, these negative effects lasted for over a decade, and there was a significant influence on the next generation: wild-caught females had calves with reduced survival to age 5. Our results suggest that wild capture has long-term consequences for reproduction, which is important not only for elephants, but also for other species in captivity.

Limited support for the X-linked grandmother hypothesis in pre-industrial Finland.

The level of kin help often depends on the degree of relatedness between a helper and the helped. In humans, grandmother help is known to increase the survival of grandchildren, though this benefit can differ between maternal grandmothers (MGMs) and paternal grandmothers (PGMs) and between grandsons and granddaughters. The X-linked grandmother hypothesis posits that differential X-chromosome relatedness between grandmothers and their grandchildren is a leading driver of differential grandchild survival between grandmother lineages and grandchild sexes. We tested this hypothesis using time-event models on a large, multigenerational dataset from pre-industrial Finland. We found that the presence of an MGM increases grandson survival more than PGM presence, and that granddaughter survival is higher than that of grandsons in the presence of a PGM. However, there was no support for the key prediction that the presence of PGMs improves granddaughter survival more than that of MGMs, diminishing the overall support for the hypothesis. Our results call for alternative explanations for differences in the effects of maternal and paternal kin to grandchild survival in humans.

Reproductive cessation and post-reproductive lifespan in Asian elephants and pre-industrial humans.

INTRODUCTION: Short post-reproductive lifespan is widespread across species, but prolonged post-reproductive life-stages of potential adaptive significance have been reported only in few mammals with extreme longevity. Long post-reproductive lifespan contradicts classical evolutionary predictions of simultaneous senescence in survival and reproduction, and raises the question of whether extreme longevity in mammals promotes such a life-history. Among terrestrial mammals, elephants share the features with great apes and humans, of having long lifespan and offspring with long dependency. However, little data exists on the frequency of post-reproductive lifespan in elephants. Here we use extensive demographic records on semi-captive Asian elephants (n = 1040) and genealogical data on pre-industrial women (n = 5336) to provide the first comparisons of age-specific reproduction, survival and post-reproductive lifespan in both of these long-lived species. RESULTS: We found that fertility decreased after age 50 in elephants, but the pattern differed from a total loss of fertility in menopausal women with many elephants continuing to reproduce at least until the age of 65 years. The probability of entering a non-reproductive state increased steadily in elephants from the earliest age of reproduction until age 65, with the longer living elephants continuing to reproduce until older ages, in contrast to humans whose termination probability increased rapidly after age 35 and reached 1 at 56 years, but did not depend on longevity. Post-reproductive lifespan reached 11-17 years in elephants and 26-27 years in humans living until old age (depending on method), but whereas half of human adult lifespan (of those reproductive females surviving to the age of 5% fecundity) was spent as post-reproductive, only one eighth was in elephants. Consequently, although some elephants have long post-reproductive lifespans, relatively few individuals reach such a phase and the decline in fertility generally parallels declines in survivorship in contrast to humans with a decoupling of senescence in somatic and reproductive functions. CONCLUSIONS: Our results show that the reproductive and survival patterns of Asian elephants differ from other long-lived animals exhibiting menopause, such as humans, and extreme longevity alone does not promote the evolution of menopause or post-reproductive lifespan, adding weight to the unusual kin-selected benefits suggested to favour such traits in humans and killer whales.

Fertility resilience varies by socioeconomic status and sex: Historical trends in childlessness across 150 years.

Fertility dynamics are key drivers of demographic change in a population. Fertility resilience is likely to vary by socioeconomic class, yet little investigated. Using a unique dataset tracking the reproduction of family lineages for 150 years, we explored childlessness by socioeconomic status and sex during the demographic transition and recurring societal and economic disturbances in Finland. Lifetime childlessness doubled from the 1800 birth cohort to the 1945-1949 cohort. Higher socioeconomic status (SES) indicated higher lifetime likelihood to reproduce. The fluctuations in childlessness over time appeared to be driven by the low socioeconomic group, showing low fertility resilience. In contrast, a steady increase was seen in high and moderate SES. Our findings suggest that the family formation of lower socioeconomic groups suffers the most during crises and does not necessarily recuperate. Preventing inequalities in family formation and reproduction should be recognized as a key challenge for population resilience to crises.

Asian elephant calf physiology and mahout perspectives during taming in Myanmar.

A quarter of Asian elephants are captive, with greater than 90% of these tamed and cared for by handlers (mahouts) in Asia. Although taming is a much-discussed welfare issue, no studies to our knowledge have empirically assessed its impact on calves, and dialogue surrounding taming often lacks perspectives of those involved. Here, we interviewed mahouts involved in taming and monitored five physiological measures (faecal glucocorticoid metabolites (FGMs), serum cortisol, glucose, creatine kinase (CK) and heterophil:lymphocyte (H:L)) over the first 10 days of taming and following six months in 41 calves undergoing taming and 16 control individuals. These measures assess the duration and intensity of stress during taming. Interviews suggested mahouts had major concerns for their safety when discussing changing taming practices, an important consideration for future management. Calf physiological measures were elevated by 50-70% (FGMs/cortisol/glucose), 135% (H:L) and greater than 500% (CK) over the first few days of taming, indicative of elevated stress, not seen to the same extent in control adults. Some measures stabilized sooner (glucose/cortisol/CK/FGM: 7-10 days) than others (H:L: one-two months), indicating mostly acute stress. Our findings inform the welfare of approximately 15 000 captive elephants around the world. Future studies should compare taming in different populations and consider calf and mahout welfare.

Sex, age, and family structure influence dispersal behaviour after a forced migration.

Dispersal does not only mean moving from one environment to another, but can also refer to shifting from one social group to another. Individual characteristics such as sex, age and family structure might influence an individual's propensity to disperse. In this study, we use a unique dataset of an evacuated World War II Finnish population, to test how sex, age, number of siblings and birth order influence an individual's dispersal away from their own social group at a time when society was rapidly changing. We found that young women dispersed more than young men, but the difference decreased with age. This suggests that young men might benefit more from staying near a familiar social group, whereas young women could benefit more from moving elsewhere to find work or spouses. We also found that having more younger brothers increased the propensity for firstborns to disperse more than for laterborns, indicating that younger brothers might pressure firstborn individuals into leaving. However, sisters did not have the same effect as brothers. Overall, the results show that individual characteristics are important in understanding dispersal behaviour, but environmental properties such as social structure and the period of flux after World War II might upend the standard predictions concerning residence and dispersal. Social media summary: Individual characteristics influence dispersal away from social group after a forced migration in a Finnish population.

Grandparental co-residence and grandchild survival: the role of resource competition in a pre-industrial population.

Although grandparents are and have been important alloparents to their grandchildren, they are not necessarily only beneficial but can also compete with grandchildren over limited resources. Competition over parental care or other resources may exist especially if grandparents live in the same household with grandchildren and it can be dependent on grandchild age. By utilizing demographic data collected from historic population registers in Finland between 1761 and 1895 (study sample n = 4041) we investigate whether grandparents living in the same household with grandchildren are detrimental or beneficial for grandchild survival. Having a living but not co-residing grandmother or grandfather were both associated with better survival whereas having a co-resident grandfather was associated with lower chance to survive for infants (age < 1 year). Separating the effect between maternal and paternal grandparents and grandmothers and grandfathers revealed no differences in the effects between lineages. Negative effect of having a co-residing grandfather was not significant when grandfathers were separated for lineage specific models. These results implicate that accounting for the co-residence status and child's age, grandparents were mostly beneficial when not co-residing with very young children and that having a co-residing grandfather at that age could be associated with lower chances to survive. Predictions made by grandmother hypothesis and resource competition both received support. The results presented here also offered comparison points to preindustrial and contemporary three-generational families.

Residential green environments are associated with human milk oligosaccharide diversity and composition.

Increased exposure to greener environments has been suggested to lead to health benefits in children, but the associated mechanisms in early life, particularly via biological mediators such as altered maternal milk composition, remain largely unexplored. We investigated the associations between properties of the mother's residential green environment, measured as (1) greenness (Normalized Difference Vegetation index, NDVI), (2) Vegetation Cover Diversity (VCDI) and (3) Naturalness Index (NI), and human milk oligosaccharides (HMOs), known for their immune- and microbiota-related health effects on the infant (N = 795 mothers). We show that HMO diversity increases and concentrations of several individual HMOs and HMO groups change with increased VCDI and NI in residential green environments. This suggests that variation in residential green environments may influence the infant via maternal milk through modified HMO composition. The results emphasize the mediating role of breastfeeding between the residential green environments and health in early life.

Severe intergenerational reproductive conflict and the evolution of menopause.

Human menopause is ubiquitous among women and is uninfluenced by modernity. In addition, it remains an evolutionary puzzle: studies have largely failed to account for diminishing selection on reproduction beyond 50 years. Using a 200-year dataset on pre-industrial Finns, we show that an important component is between-generation reproductive conflict among unrelated women. Simultaneous reproduction by successive generations of in-laws was associated with declines in offspring survivorship of up to 66%. An inclusive fitness model revealed that incorporation of the fitness consequences of simultaneous intergenerational reproduction between in-laws, with those of grandmothering and risks of dying in childbirth, were sufficient to generate selection against continued reproduction beyond 51 years. Decomposition of model estimates suggested that the former two were most influential in generating selection against continued reproduction. We propose that menopause evolved, in part, because of age-specific increases in opportunities for intergenerational cooperation and reproductive competition under ecological scarcity.

Parental feeding practices and child eating behavior in different socioeconomic neighborhoods and their association with childhood weight. The STEPS study.

Child obesity risk, child eating behavior and parental feeding practices show a graded association with individual level socioeconomic status. However, their associations with neighborhood socioeconomic disadvantage are largely unknown. In this study (n = 682), we investigated how parental feeding practices and child eating behaviors were associated with body mass index and risk of overweight at preschool age in affluent and disadvantaged neighborhoods. We found that high food approach tendency in disadvantaged neighborhoods predicted higher body mass index and increased the risk of overweight at the age of 6 years compared with affluent neighborhoods. Our results suggest that children's eating habits may have stronger impact on overweight risk in disadvantaged than in affluent neighborhoods.

Parental Self-Efficacy and Child Diet Quality between Ages 2 and 5: The STEPS Study.

Parental self-efficacy (PSE), a measure of the subjective competence in the parental role, has been linked with child well-being and health. Research on the influence of PSE on child eating habits is scarce, and the few studies have concentrated on certain food groups, such as vegetables or fruits, and have mostly included only maternal PSE. Thus, the aim of this study was to explore the associations between PSE (separately for mothers and fathers and as a total family-level score) and child diet quality in a cross-sectional and longitudinal study setting. PSE was measured at child ages of 1.5 and 5 years, and diet quality was measured at ages 2 and 5. Participants are from the Steps to Healthy Development (STEPS) Study (n = 270-883). We found that maternal PSE and family level PSE score were associated with child diet quality. Paternal PSE was not, but the dimension Routines was associated with child diet quality. PSE was similarly associated with child diet quality at both age points. Our results suggest that PSE is an important construct in the development of healthy dietary habits in children, and supporting parenting programs aimed at higher PSE could promote healthy diet quality in children.

Psychological Distress During the Retirement Transition and the Role of Psychosocial Working Conditions and Social Living Environment.

OBJECTIVES: Mental health is determined by social, biological, and cultural factors and is sensitive to life transitions. We examine how psychosocial working conditions, social living environment, and cumulative risk factors are associated with mental health changes during the retirement transition. METHOD: We use data from the Finnish Retirement and Aging study on public sector employees (n = 3,338) retiring between 2014 and 2019 in Finland. Psychological distress was measured with the General Health Questionnaire annually before and after retirement and psychosocial working conditions, social living environment, and accumulation of risk factors at the study wave prior to retirement. RESULTS: Psychological distress decreased during the retirement transition, but the magnitude of the change was dependent on the contexts individuals retire from. Psychological distress was higher among those from poorer psychosocial working conditions (high job demands, low decision authority, job strain), poorer social living environment (low neighborhood social cohesion, small social network), and more cumulative risk factors (work/social/both). During the retirement transition, greatest reductions in psychological distress were observed among those with poorer conditions (work: absolute and relative changes, p [Group × Time interactions] < .05; social living environment and cumulative risk factors: absolute changes, p [Group × Time interactions] < .05). DISCUSSION: Psychosocial work-related stressors lead to quick recovery during the retirement transition but the social and cumulative stressors have longer-term prevailing effects on psychological distress. More studies are urged incorporating exposures across multiple levels or contexts to clarify the determinants of mental health during the retirement transition and more generally at older ages.

Investigating associations between nematode infection and three measures of sociality in Asian elephants.

Abstract: Frequent social interactions, proximity to conspecifics, and group density are main drivers of infections and parasite transmissions. However, recent theoretical and empirical studies suggest that the health benefits of sociality and group living can outweigh the costs of infection and help social individuals fight infections or increase their infection-related tolerance level. Here, we combine the advantage of studying artificially created social work groups with different demographic compositions with free-range feeding and social behaviours in semi-captive Asian elephants (Elephas maximus), employed in timber logging in Myanmar. We examine the link between gastro-intestinal nematode load (strongyles and Strongyloides spp.), estimated by faecal egg counts, and three different aspects of an elephant's social world: individual solitary behaviour, work group size, and work group sex ratio. Controlling for sex, age, origin, time since last deworming treatment, year, human sampler bias, and individual identity, we found that infection by nematodes ranged from 0 to 2720 eggs/g between and within 26 male and 45 female elephants over the 4-year study period. However, such variation was not linked to any investigated measures of sociality in either males or females. Our findings highlight the need for finer-scale studies, establishing how sociality is limited by, mitigates, or protects against infection in different ecological contexts, to fully understand the mechanisms underlying these pathways. Significance statement: Being social involves not only benefits, such as improved health, but also costs, including increased risk of parasitism and infectious disease. We studied the relationship between and three different sociality measures-solitary behaviour, group size, and the proportion of females to males within a group-and infection by gut nematodes (roundworms), using a unique study system of semi-captive working Asian elephants. Our system allows for observing how infection is linked to sociality measures across different social frameworks. We found that none of our social measures was associated with nematode infection in the studied elephants. Our results therefore suggest that here infection is not a large cost to group living, that it can be alleviated by the benefits of increased sociality, or that there are weak infection-sociality associations present which could not be captured and thus require finer-scale measures than those studied here. Overall, more studies are needed from a diverse range of systems that investigate specific aspects of social infection dynamics. Supplementary Information: The online version contains supplementary material available at 10.1007/s00265-022-03192-8.

Age related variation of health markers in Asian elephants.

Although senescence is often observed in the wild, its underlying mechanistic causes can rarely be studied alongside its consequences, because data on health, molecular and physiological measures of senescence are rare. Documenting how different age-related changes in health accelerate ageing at a mechanistic level is key if we are to better understand the ageing process. Nevertheless, very few studies, particularly on natural populations of long-lived animals, have investigated age-related variation in biological markers of health and sex differences therein. Using blood samples collected from semi-captive Asian elephants, we show that pronounced differences in haematology, blood chemistry, immune, and liver functions among age classes are also evident under natural conditions in this extremely long-lived mammal. We provide strong support that overall health declined with age, with progressive declines in immune and liver functions similarly in both males and females. These changes parallel those mainly observed to-date in humans and laboratory mammals, and suggest a certain ubiquity in the ageing patterns.

Offspring fertility and grandchild survival enhanced by maternal grandmothers in a pre-industrial human society.

Help is directed towards kin in many cooperative species, but its nature and intensity can vary by context. Humans are one of few species in which grandmothers invest in grandchildren, and this may have served as an important driver of our unusual life history. But helping behaviour is hardly uniform, and insight into the importance of grandmothering in human evolution depends on understanding the contextual expression of helping benefits. Here, we use an eighteenth-nineteenth century pre-industrial genealogical dataset from Finland to investigate whether maternal or paternal grandmother presence (lineage relative to focal individuals) differentially affects two key fitness outcomes of descendants: fertility and survival. We found grandmother presence shortened spacing between births, particularly at younger mother ages and earlier birth orders. Maternal grandmother presence increased the likelihood of focal grandchild survival, regardless of whether grandmothers had grandchildren only through daughters, sons, or both. In contrast, paternal grandmother presence was not associated with descendants' fertility or survival. We discuss these results in terms of current hypotheses for lineage differences in helping outcomes.