Evolutionary Life History Theory Research Articles

Income and Sex Moderate the Association Between Population Density and Reproduction: A Multilevel Analysis of Life History Strategies Across 23 Nations.

While previous studies guided by evolutionary life history theory have revealed several important socioecological moderators of the influence of population density (PD) on reproduction, absent is an understanding of how individual-level factors such as personal resources and sex differences might interact and play a role. Using data from a large sample of clients (N = 4,432,440) of an online dating company spanning 317 states nested within 23 countries, we contributed a robust multilevel analysis of life history effects by assessing the interaction between state-level PD and individual-level income on offspring quantity, and we further qualified this analysis by sex. Consistent with previous research, PD was negatively correlated with having children. Consistent with our novel hypotheses, this negative relationship was moderated by income such that the link between PD and low fertility became weaker with increasing levels of income and these patterns were stronger for men than for women. These results held despite controlling for a variety of country-level, state-level, and individual-level confounds. Findings are discussed together with theoretical and practical implications for the management of fertility based on evolutionary life history perspectives.

Human energetic stress associated with upregulation of spatial cognition.

Evolutionary life history theory has a unique potential to shed light on human adaptive capabilities. Ultra-endurance challenges are a valuable experimental model allowing the direct testing of phenotypic plasticity via physiological trade-offs in resource allocation. This enhances our understanding of how the body prioritizes different functions when energetically stressed. However, despite the central role played by the brain in both hominin evolution and metabolic budgeting, cognitive plasticity during energetic deficit remains unstudied. We considered human cognitive plasticity under conditions of energetic deficit by evaluating variability in performance in three key cognitive domains. To achieve this, cognitive performance in a sample of 48 athletes (m = 29, f = 19) was assessed before and after competing in multiday ultramarathons. We demonstrate that under conditions of energetic deficit, performance in tasks of spatial working memory (which assessed ability to store location information, promoting landscape navigation and facilitating resource location and calorie acquisition) increased. In contrast, psychomotor speed (reaction time) remained unchanged and episodic memory performance (ability to recall information about specific events) decreased. We propose that prioritization of spatial working memory performance during conditions of negative energy balance represents an adaptive response due to its role in facilitating calorie acquisition. We discuss these results with reference to a human evolutionary trajectory centred around encephalisation. Encephalisation affords great plasticity, facilitating rapid responses tailored to specific environmental conditions, and allowing humans to increase their capabilities as a phenotypically plastic species.

Food insecurity, diet and mental distress among resource insecure students during COVID-19.

It is well documented that college student populations are vulnerable to food insecurity and other adverse environmental conditions. Additionally, exposure to environmental adversity can have deleterious, long-term effects on physical and mental health. This study applies evolutionary life history theory to examine the relationship between environmental adversity, mental distress and diet among resource insecure university students during the COVID-19 pandemic. Structured and semi-structured surveys were used to assess perceptions of environmental adversity (including mortality risk, food insecurity and resource availability; and changes in these factors over the course of COVID-19), mental distress, diet and use of campus support services. Participants included 51 college students recruited through an economic crisis center located at a large public university in southern California. Most students were experiencing mental distress and food insecurity, and food insecurity and other components of adversity increased during COVID-19. Food insecurity was significantly associated with both perceived extrinsic mortality risk and mental distress, whereas mental distress was significantly associated with reduced dietary quality and caloric intake. Use of two or more campus support resources and/or living with family or rent free disrupted the associations of food insecurity with extrinsic mortality risk and mental distress. This study contributes to a growing body of applied evolutionary frameworks concerned with the health and wellbeing of economically vulnerable populations. It also provides novel insights informed by life history theory into interventions and recommendations for improving support services for financially insecure college students.

Life history trade-offs associated with exposure to low maternal capital are different in sons compared to daughters: Evidence from a prospective Brazilian birth cohort.

BackgroundEnvironmental exposures in early life explain variability in many physiological and behavioural traits in adulthood. Recently, we showed that exposure to a composite marker of low maternal capital explained the clustering of adverse behavioural and physical traits in adult daughters in a Brazilian birth cohort. These associations were strongly mediated by whether or not the daughter had reproduced by the age of 18 years. Using evolutionary life history theory, we attributed these associations to trade-offs between competing outcomes, whereby daughters exposed to low maternal capital prioritised investment in reproduction and defence over maintenance and growth. However, little is known about such trade-offs in sons.MethodsWe investigated 2,024 mother–son dyads from the same birth cohort. We combined data on maternal height, body mass index, income, and education into a composite “maternal capital” index. Son outcomes included reproductive status at the age of 18 years, growth trajectory, adult anthropometry, body composition, cardio-metabolic risk, educational attainment, work status, and risky behaviour (smoking, violent crime). We tested whether sons' early reproduction and exposure to low maternal capital were associated with adverse outcomes and whether this accounted for the clustering of adverse outcomes within individuals.ResultsSons reproducing early were shorter, less educated, and more likely to be earning a salary and showing risky behaviour compared to those not reproducing, but did not differ in foetal growth. Low maternal capital was associated with a greater likelihood of sons' reproducing early, leaving school, and smoking. High maternal capital was positively associated with sons' birth weight, adult size, and staying in school. However, the greater adiposity of high-capital sons was associated with an unhealthier cardio-metabolic profile.ConclusionExposure to low maternal investment is associated with trade-offs between life history functions, helping to explain the clustering of adverse outcomes in sons. The patterns indicated future discounting, with reduced maternal investment associated with early reproduction but less investment in growth, education, or healthy behaviour. However, we also found differences compared to our analyses of daughters, with fewer physical costs associated with early reproduction. Exposure to intergenerational “cycles of disadvantage” has different effects on sons vs. daughters, hence interventions may have sex-specific consequences.

The selection force weakens with age because ageing evolves and not vice versa

According to the classic theory of life history evolution, ageing evolves because selection on traits necessarily weakens throughout reproductive life. But this inexorable decline of the selection force with adult age was shown to crucially depend on specific assumptions that are not necessarily fulfilled. Whether ageing still evolves upon their relaxation remains an open problem. Here, we propose a fully dynamical model of life history evolution that does not presuppose any specific pattern the force of selection should follow. The model shows: (i) ageing can stably evolve, but negative ageing cannot; (ii) when ageing is a stable equilibrium, the associated selection force decreases with reproductive age; (iii) non-decreasing selection is either a transient or an unstable phenomenon. Thus, we generalize the classic theory of the evolution of ageing while overturning its logic: the decline of selection with age evolves dynamically, and is not an implicit consequence of certain assumptions.

Many lifetime growth trajectories for a single mammal.

Despite their importance in shaping life history tactics and population dynamics, individual growth trajectories have only been rarely explored in the wild because their analysis requires multiple measurements of individuals throughout their lifetime and some knowledge of age, a key timer of body growth. The availability of long‐term longitudinal studies of two wild boar populations subjected to contrasting environments (rich vs. poor) provided an opportunity to analyze individual growth trajectories. We quantified wild boar growth trajectories at both the population and the individual levels using standard growth models (i.e., Gompertz, logistic, and monomolecular models) that encompass the expected range of growth shapes in determinate growers. Wild boar is a rather altricial species, with a polygynous mating system and is strongly sexually dimorphic in size. According to current theories of life history evolution, we thus expect wild boar to display a sex‐specific Gompertz type growth trajectory and lower sexual size dimorphism in the poorer environment. While wild boar displayed the expected Gompertz type trajectory in the rich site at the population level, we found some evidence for potential differences in growth shapes between populations and individuals. Asymptotic body mass, growth rate and timing of maximum growth rate differed as well, which indicates a high flexibility of growth in wild boar. We also found a cohort effect on asymptotic body mass, which suggests that environmental conditions early in life shape body mass at adulthood in this species. Our findings demonstrate that body growth trajectories in wild boar are highly diverse in relation to differences of environmental context, sex and year of birth. Whether the intermediate ranking of wild boar along the precocial–altricial continuum of development at birth may explain the ability of this species to exhibit this high diversity of growth patterns remains to be investigated.

Связь демографических показателей здоровья населения и экологических факторов в городах России

Results. Comparison of groups of cities with different levels of air pollution in terms of the total fertility rate and the birth-death ratio revealed significant differences between the groups in 2014 (significance levels are 0.018 and 0.025, respectively) and their absence in 2015 and 2016. At the same time, in groups of cities, with an increase in the level of air pollution, an increase in the median values of the total fertility rates and the birth-death rates is noted. Comparison of groups of cities according to the aging index revealed a significant heterogeneity of groups with different levels of air pollution in 2014, 2015, 2016: significance levels are equal to 0.0007; 0.005; 0.002 respectively. In urban groups, with an increase in air pollution, the median value of the aging index decreases. Conclusion. An analysis of the relationship between demographic indicators of population health and the level of air pollution showed that the most sensitive to the level of air pollution are indicators such as the total fertility rate, the birth-death ratio and the aging index. In groups of cities, with an increase in the level of air pollution, the median values of the total fertility rate and the birth-death ratio increase, while the median values of the aging index decrease. The results obtained are consistent with the provisions of the theory of life history evolution. This research was performed according to the Development program of the Interdisciplinary Scientific and Educational School of M.V. Lomonosov Moscow State University “The future of the planet and global environmental change”.

Repeated loss of variation in insect ovary morphology highlights the role of development in life-history evolution.

The number of offspring an organism can produce is a key component of its evolutionary fitness and life history. Here we perform a test of the hypothesized trade-off between the number and size of offspring using thousands of descriptions of the number of egg-producing compartments in the insect ovary (ovarioles), a common proxy for potential offspring number in insects. We find evidence of a negative relationship between egg size and ovariole number when accounting for adult body size. However, in contrast to prior claims, we note that this relationship is not generalizable across all insect clades, and we highlight several factors that may have contributed to this size-number trade-off being stated as a general rule in previous studies. We reconstruct the evolution of the arrangement of cells that contribute nutrients and patterning information during oogenesis (nurse cells), and show that the diversification of ovariole number and egg size have both been largely independent of their presence or position within the ovariole. Instead, we show that ovariole number evolution has been shaped by a series of transitions between variable and invariant states, with multiple independent lineages evolving to have almost no variation in ovariole number. We highlight the implications of these invariant lineages on our understanding of the specification of ovariole number during development, as well as the importance of considering developmental processes in theories of life-history evolution.

Life History Is a Major Source of Adaptive Individual and Species Differences: a Critical Commentary on Zietsch and Sidari (2020)

Zietsch and Sidari (2020) argue that life history theory does not offer an appropriate model for understanding inter-individual trait covariation. We examine in great detail four major claims of Zietsch and Sidari’s critique of life history theory as an explanation of inter-individual covariation among phenotypic, especially psychometric, traits. We review relevant theoretical and empirical research overlooked by Zietsch and Sidari and conduct reanalyses of comparative cross-species “pace-of-life” and human behaviour-genetic data. Our results challenge their arguments concerning (a) the implications for life history theory of the absence of individual-differences-level covariation in a variety of species and (b) the genetic aetiology of psychometric life history covariance. None of the four major claims made by Zietsch and Sidari withstand close scrutiny. Critiques of life history theory, such as the one developed by Zietsch and Sidari, should (if they are to be more persuasive) show what alternative theory might be at least as successful as life history theory in consiliently and parsimoniously explaining patterns of covariation among various traits within and between species, including the predictable absence of such covariation among certain traits. Evolutionary life history theory—as applied to non-human animals and humans—offers one of the broadest and empirically best-supported frameworks for understanding individual differences in physiology, cognition, behaviour, reproduction, and other traits and life outcomes.

Five reasons COVID-19 is less severe in younger age-groups.

The severity of COVID-19 is age-related, with the advantage going to younger age-groups. Five reasons are presented. The first two are well-known, are being actively researched by the broader medical community, and therefore are discussed only briefly here. The third, fourth and fifth reasons derive from evolutionary life history theory, and potentially fill gaps in current understanding of why and how young and old age-groups respond differently to infection with SARS-CoV-2. Age of onset of generalized somatic aging and the timing of its progression are identified as important causes of these disparities, as are specific antagonistic pleiotropic tradeoffs in immune system function. Lay Summary: Covid-19 is less severe in younger age-groups than it is in older age-groups. Five advantages of youth are identified and explained in light of evolutionary life history theory, with a focus on the pattern of aging and specific tradeoffs between early and late immune system function.

An evolutionary life history approach to understanding mental health.

In recent years, evolutionary life history theory has been used as a heuristic framework to understand mental health. This article reviews the life history theory and its integration with mental disorders and then introduces representative research methods and related empirical studies in the field of evolutionary psychopathology. In the end, this article concludes with future directions for further research examining and developing the evolutionary psychopathological framework.

Parental substance misuse and reproductive timing in offspring: A genetically informed study

Abstract Parents with substance misuse provide their children with a potentially risky rearing environment. According to the evolutionary life history theory, such environments steer individuals towards faster reproductive strategy. However, parents providing their children with hazardous environments may also pass on genes associated with early parenthood. In register data on individuals born in Sweden 1973–1993 (N = 2,176,128), the hazard ratio of entering parenthood by age 25 was 1.70 (95% CI 1.69–1.72) and 1.85 (1.82–1.89) among offspring of fathers and mothers with substance misuse, respectively, compared to others. In analyses using an offspring-of-siblings design in three types of parental sibling pairs (half siblings, full siblings and dizygotic twins, and monozygotic twins) increasingly controlling for genetic confounding, associations between parental substance misuse and offspring's early reproduction gradually attenuated. Our results suggest that the association between parental substance misuse and earlier parenthood in offspring is at least partly genetically confounded. Life history theory should be further tested with genetically informative research designs.

Coevolution of body size and metabolic rate in vertebrates: a life-history perspective.

ABSTRACTDespite many decades of research, the allometric scaling of metabolic rates (MRs) remains poorly understood. Here, we argue that scaling exponents of these allometries do not themselves mirror one universal law of nature but instead statistically approximate the non‐linearity of the relationship between MR and body mass. This ‘statistical’ view must be replaced with the life‐history perspective that ‘allows’ organisms to evolve myriad different life strategies with distinct physiological features. We posit that the hypoallometric allometry of MRs (mass scaling with an exponent smaller than 1) is an indirect outcome of the selective pressure of ecological mortality on allocation ‘decisions’ that divide resources among growth, reproduction, and the basic metabolic costs of repair and maintenance reflected in the standard or basal metabolic rate (SMR or BMR), which are customarily subjected to allometric analyses. Those ‘decisions’ form a wealth of life‐history variation that can be defined based on the axis dictated by ecological mortality and the axis governed by the efficiency of energy use. We link this variation as well as hypoallometric scaling to the mechanistic determinants of MR, such as metabolically inert component proportions, internal organ relative size and activity, cell size and cell membrane composition, and muscle contributions to dramatic metabolic shifts between the resting and active states. The multitude of mechanisms determining MR leads us to conclude that the quest for a single‐cause explanation of the mass scaling of MRs is futile. We argue that an explanation based on the theory of life‐history evolution is the best way forward.

Life History Transitions at the Origins of Agriculture: A Model for Understanding How Niche Construction Impacts Human Growth, Demography and Health.

Over recent millennia, human populations have regularly reconstructed their subsistence niches, changing both how they obtain food and the conditions in which they live. For example, over the last 12,000 years the vast majority of human populations shifted from foraging to practicing different forms of agriculture. The shift to farming is widely understood to have impacted several aspects of human demography and biology, including mortality risk, population growth, adult body size, and physical markers of health. However, these trends have not been integrated within an over-arching conceptual framework, and there is poor understanding of why populations tended to increase in population size during periods when markers of health deteriorated. Here, we offer a novel conceptual approach based on evolutionary life history theory. This theory assumes that energy availability is finite and must be allocated in competition between the functions of maintenance, growth, reproduction, and defence. In any given environment, and at any given stage during the life-course, natural selection favours energy allocation strategies that maximise fitness. We argue that the origins of agriculture involved profound transformations in human life history strategies, impacting both the availability of energy and the way that it was allocated between life history functions in the body. Although overall energy supply increased, the diet composition changed, while sedentary populations were challenged by new infectious burdens. We propose that this composite new ecological niche favoured increased energy allocation to defence (immune function) and reproduction, thus reducing the allocation to growth and maintenance. We review evidence in support of this hypothesis and highlight how further work could address both heterogeneity and specific aspects of the origins of agriculture in more detail. Our approach can be applied to many other transformations of the human subsistence niche, and can shed new light on the way that health, height, life expectancy, and fertility patterns are changing in association with globalization and nutrition transition.

The Dark Triad and Sexual Assertiveness Predict Sexual Coercion Differently in Men and Women.

Sexual coercion is a global problem that has been studied widely with regard to various characteristics of the perpetrators. The Dark Triad of personality (i.e., narcissism, Machiavellianism, and primary and secondary psychopathy) has been indicated as an important predictor of coercive cognitions and behaviors. In this study, we report findings of an online study (N = 208), exploring the relationship between sexual coercion, the Dark Triad, and sexual assertiveness (i.e., strategies for achieving sexual autonomy). We found that the Dark Triad was a stronger predictor of sexual coercion in men than in women. In men, all the Dark Triad components were significantly, positively correlated with sexual coercion, and narcissism and Machiavellianism had significant, negative correlations with sexual assertiveness. In women, only narcissism had a significant, positive correlation with sexual coercion, and the Dark Triad traits were not correlated with sexual assertiveness. In regression analyses, controlling for shared variance between the predictor variables, high secondary psychopathy, and low sexual assertiveness emerged as significant predictors of coercion in men. Only narcissism was a significant positive predictor in women. We discuss the results with a reference to evolutionary Life History theory.

The Centrality of Ancestral Grandmothering in Human Evolution.

When Fisher, Williams, and Hamilton laid the foundations of evolutionary life history theory, they recognized elements of what became a grandmother hypothesis to explain the evolution of human postmenopausal longevity. Subsequent study of modern hunter-gatherers, great apes, and the wider mammalian radiation has revealed strong regularities in development and behavior that show additional unexpected consequences that ancestral grandmothering likely had on human evolution, challenging the hypothesis that ancestral males propelled the evolution of our radiation by hunting to provision mates and offspring. Ancestral grandmothering has become a serious contender to explain not only the large fraction of post-fertile years women live and children's prolonged maturation yet early weaning; it also promises to help account for the pair bonding that distinguishes humans from our closest living evolutionary cousins, the great apes (and most other mammals), the evolution of our big human brains, and our distinctive preoccupation with reputations, shared intentionality and persistent cultural learning that begins in infancy.

Evolutionary life history theory as an organising framework for cohort studies: insights from the Cebu Longitudinal Health and Nutrition Survey

ABSTRACTBy tracking a group of individuals through time, cohort studies provide fundamental insights into the developmental time course and causes of health and disease. Evolutionary life history theory seeks to explain patterns of growth, development, reproduction and senescence, and inspires a range of hypotheses that are testable using the longitudinal data from cohort studies. Here we review two decades of life history theory-motivated work conducted in collaboration with the Cebu Longitudinal Health and Nutrition Survey (CLHNS), a birth cohort study that enrolled more than 3000 pregnant women in the Philippines in 1983 and has since followed these women, their offspring and grandoffspring. This work has provided evidence that reproduction carries “costs” to cellular maintenance functions, potentially speeding senescence, and revealed an unusual form of genetic plasticity in which the length of telomeres inherited across generations is influenced by reproductive timing in paternal ancestors. Men in Cebu experience hormonal and behavioural changes in conjunction with changes in relationship and fatherhood status that are consistent with predictions based upon other species that practice bi-parental care. The theoretical expectation that early life cues of mortality or environmental unpredictability will motivate a “fast” life history strategy are confirmed for behavioural components of reproductive decision making, but not for maturational tempo, while our work points to a broader capacity for early life developmental calibration of systems like immunity, reproductive biology and metabolism. Our CLHNS findings illustrate the power of life history theory as an integrative, lifecourse framework to guide longitudinal studies of human populations.

Prenatal anxiety, breastfeeding and child growth and puberty: linking evolutionary models with human cohort studies

Background: Stress experienced by mothers during pregnancy can have both immediate and long-term effects on child development, potentially mediated by breastfeeding.Aim: Using a UK birth cohort study, we asked how maternal stress relates to breastfeeding and consequences for growth and puberty onset.Subjects and methods: We analysed data from the Avon Longitudinal Study of Parents and Children, collected via questionnaires and clinic visits (N: 698–8,506). We used reports of prenatal anxiety, breastfeeding, early growth and age at menarche or first voice change. Confounding by maternal age, parity, smoking, education and body mass index (BMI) was considered.Results: Mothers with higher levels of reported anxiety were less likely to breastfeed (Odds ratio (OR): 0.83, 95% confidence interval (CI): 0.71, 0.97). Breastfed infants had slower growth before weaning, although growth differences were unclear thereafter. Being breastfed for more than six months was associated with later puberty onset in females (2.76 months later than non-breastfed; CI: 0.9, 4.63), although the association was attenuated by confounders and BMI (1.51 months, CI: −0.38, 3.40). No association between breastfeeding and puberty onset in males was found.Conclusion: Our studies fit results shown previously, and we consider these in light of evolutionary life history theory while discussing key challenges in such an approach.

Evolutionary life history theory as an organising framework for cohort studies: insights from the Cebu Longitudinal Health and Nutrition Survey

Evolutionary life history theory as an organising framework for cohort studies: insights from the Cebu Longitudinal Health and Nutrition Survey

Are mothers less likely to breastfeed in harsh environments? Physical environmental quality and breastfeeding in the Born in Bradford study.

We use the United Kingdom's Born in Bradford study to investigate whether women in lower quality environments are less likely to breastfeed. We use measures of physical environmental quality (water disinfectant by-products [DBPs], air pollution, passive cigarette smoke, and household condition) alongside socio-economic indicators, to explore in detail how different exposures influence breastfeeding. Drawing on evolutionary life history theory, we predict that lower environmental quality will be associated with lower odds of initiating, and higher hazards of stopping, breastfeeding. As low physical environmental quality may increase the risk of adverse birth outcomes, which may in turn affect breastfeeding chances, we also test for mediation by gestational age, birthweight, head circumference, and abdominal circumference. Our sample is composed of mothers who gave birth at the Bradford Royal Infirmary in West Yorkshire between March 2007 and December 2010 for whom breastfeeding initiation data was available. Analyses were stratified by the two largest ethnic groups: White British (n=3,951) and Pakistani-origin (n=4,411) mothers. After controlling for socio-economic position, Pakistani-origin mothers had lower chances of initiating and higher chances of stopping breastfeeding with increased water DBP exposure (e.g., OR for 0.03-0.61 vs. <0.02μg/day dibromochloromethane exposure 0.70 [0.58-0.83], HR 1.16 [0.99-1.36]), greater air pollution exposure predicted lower chances of initiation for both ethnic groups (e.g., OR for 10μg/m3 increase in nitrogen dioxide 0.81 [0.66-0.99] for White British mothers and 0.79 [0.67-0.94] for Pakistani-origin mothers) but also a reduced hazard of stopping breastfeeding for White British mothers (HR 0.65 [0.52-0.80]), and exposure to household damp/mould predicted higher chances of breastfeeding initiation amongst White British mothers (OR 1.66 [1.11-2.47]). We found no evidence that physical environmental quality effects on breastfeeding were mediated through birth outcomes amongst Pakistani-origin mothers and only weak evidence (p<0.10) amongst White British mothers (exposure to passive cigarette smoke was associated with having lower birthweight infants who were in turn less likely to be breastfed whereas greater air pollution exposure was associated with longer gestations and in turn reduced hazards of stopping breastfeeding). Overall, our findings suggest that there is differential susceptibility to environmental exposures according to ethnicity. Although the water DBP results for Pakistani-origin mothers and air pollution-initiation results for both ethnic groups support our hypothesis that mothers exhibit reduced breastfeeding in poorer quality environments, several physical environmental quality indicators showed null or positive associations with breastfeeding outcomes. We consider physiological explanations for our findings and their implications for life history theory and public health policy.