scholarly journals Does extrinsic mortality accelerate the pace of life? A bare-bones approach

2019 ◽  
Author(s):  
Jean-Baptiste André ◽  
François Rousset

1AbstractIt is commonly asserted that when extrinsic mortality is high, individuals should invest early in reproduction. This intuition thrives in the literature on life-history theory and human behavior, yet it has been criticized repeatedly on the basis of mathematical models. The intuition is indeed wrong; but a recent theoretical criticism has confused the reason why it is wrong, thereby obscuring earlier and sounder criticisms. In the present article, based on the simplest possible model, we sought to clarify these issues. We confirm earlier findings that extrinsic mortality can affect the evolution of pace of life, not because it leaves little time to reproduce, but through its effects on density-dependent competition. This result highlights the importance of accounting for density-dependence in theoretical models and data analyses. Further, we find little support for the recent claim that the direction of selection on a reaction norm in a variable environment cannot be easily inferred from models made in homogeneous environments. In conclusion, although life-history theory is still imperfect, it has provided simple results that deserve to be understood.

2009 ◽  
Vol 87 (1) ◽  
pp. 8-19 ◽  
Author(s):  
Patrik Karell ◽  
Hannu Pietiäinen ◽  
Heli Siitari ◽  
Tuomo Pihlaja ◽  
Pekka Kontiainen ◽  
...  

Life-history theory predicts increased investment in current reproduction when future reproduction is uncertain and a more balanced investment in current and future reproduction when prospects for both are good. The outcome of the balance in parental allocation depends on which life-history component maximizes the fitness benefits. In our study system, a 3-year vole cycle generates good prospects of current and future reproduction for Ural owls ( Strix uralensis Pallas, 1771) in increase vole phases and uncertain prospects in decrease vole phases. We supplementary-fed Ural owls during the nestling period in 2002 (an increase phase) and 2003 (a decrease phase), and measured offspring growth, parental effort, and physiological health by monitoring haematocrit, leucocyte profiles, intra- and inter-celluar blood parasites, and (in 2003) humoral antibody responsiveness. Food supplementation reduced parental feeding rate in both years, but improved a female parent’s health only in 2002 (an increase phase) and had no effects on males in either year. Nevertheless, supplementary-fed offspring reached higher asymptotic mass and fledged earlier in both years. Furthermore, early fledging reduced offspring exposure to blood-sucking black flies (Diptera, Simuliidae) in the nest. We discuss how parental allocation of resources to current and future reproduction may vary under variable food conditions.


2021 ◽  
pp. 1-11
Author(s):  
Marco Del Giudice ◽  
John D. Haltigan

Abstract The field of psychopathology is in a transformative phase, and is witnessing a renewed surge of interest in theoretical models of mental disorders. While many interesting proposals are competing for attention in the literature, they tend to focus narrowly on the proximate level of analysis and lack a broader understanding of biological function. In this paper, we present an integrative framework for mental disorders built on concepts from life history theory, and describe a taxonomy of mental disorders based on its principles, the fast–slow–defense model (FSD). The FSD integrates psychopathology with normative individual differences in personality and behavior, and allows researchers to draw principled distinctions between broad clusters of disorders, as well as identify functional subtypes within current diagnostic categories. Simulation work demonstrates that the model can explain the large-scale structure of comorbidity, including the apparent emergence of a general “p factor” of psychopathology. A life history approach also provides novel integrative insights into the role of environmental risk/protective factors and the developmental trajectories of various disorders.


2020 ◽  
Vol 41 (6) ◽  
pp. 486-492 ◽  
Author(s):  
Jean-Baptiste André ◽  
François Rousset

2015 ◽  
Vol 370 (1673) ◽  
pp. 20140234 ◽  
Author(s):  
Hanna Kokko ◽  
Michael E. Hochberg

Studies of body size evolution, and life-history theory in general, are conducted without taking into account cancer as a factor that can end an organism's reproductive lifespan. This reflects a tacit assumption that predation, parasitism and starvation are of overriding importance in the wild. We argue here that even if deaths directly attributable to cancer are a rarity in studies of natural populations, it remains incorrect to infer that cancer has not been of importance in shaping observed life histories. We present first steps towards a cancer-aware life-history theory, by quantifying the decrease in the length of the expected reproductively active lifespan that follows from an attempt to grow larger than conspecific competitors. If all else is equal, a larger organism is more likely to develop cancer, but, importantly, many factors are unlikely to be equal. Variations in extrinsic mortality as well as in the pace of life—larger organisms are often near the slow end of the fast–slow life-history continuum—can make realized cancer incidences more equal across species than what would be observed in the absence of adaptive responses to cancer risk (alleviating the so-called Peto's paradox). We also discuss reasons why patterns across species can differ from within-species predictions. Even if natural selection diminishes cancer susceptibility differences between species, within-species differences can remain. In many sexually dimorphic cases, we predict males to be more cancer-prone than females, forming an understudied component of sexual conflict.


2012 ◽  
Vol 279 (1740) ◽  
pp. 2998-3002 ◽  
Author(s):  
David Waynforth

Life-history theoretical models show that a typical evolutionarily optimal response of a juvenile organism to high mortality risk is to reach reproductive maturity earlier. Experimental studies in a range of species suggest the existence of adaptive flexibility in reproductive scheduling to maximize fitness just as life-history theory predicts. In humans, supportive evidence has come from studies comparing neighbourhoods with different mortality rates, historical and cross-cultural data. Here, the prediction is tested in a novel way in a large ( n = 9099), longitudinal sample using data comparing age at first reproduction in individuals with and without life-expectancy-reducing chronic disease diagnosed during childhood. Diseases selected for inclusion as chronic illnesses were those unlikely to be significantly affected by shifting allocation of effort away from reproduction towards survival; those which have comparatively large effects on mortality and life expectancy; and those which are not profoundly disabling. The results confirmed the prediction that chronic disease would associate with early age at first reproduction: individuals growing up with a serious chronic disease were 1.6 times more likely to have had a first child by age 30. Analysis of control variables also confirmed past research findings on links between being raised father-absent and early pubertal development and reproduction.


2021 ◽  
Vol 12 ◽  
Author(s):  
Benjamin Otto ◽  
Lisa Kokkelink ◽  
Martin Brüne

“Borderline Personality Disorder” (BPD) is associated with heightened risk for cardiovascular disease and other stress-associated somatic consequences, which is poorly understood in terms of causal mechanisms, such as childhood trauma. Here, we tested the hypothesis suggesting that BPD reflects a fast “Pace-of-Life-Syndrome” (PoLS). Ninety-five women (44 diagnosed with BPD) were recruited to examine psychological correlates of PoLS, including life history features, personality dimensions, aggressiveness, chronic stress, borderline symptom severity, childhood trauma, and allostatic load (AL). In line with expectations, BPD patients had significantly higher scores suggestive of a fast PoLS than controls, they were more aggressive, more burdened with chronic stress and were exposed to more severe childhood adversity. Childhood trauma predicted PoLS, which in turn predicted AL. The present study thus provides direct evidence of psychological and somatic traits associated with the fast end of the PoLS spectrum in females with BPD. Findings are discussed with regard to clinical implications.


2009 ◽  
Vol 2009 ◽  
pp. 1-6 ◽  
Author(s):  
Deborah M. Sloboda ◽  
Alan S. Beedle ◽  
Cinda L. Cupido ◽  
Peter D. Gluckman ◽  
Mark H. Vickers

Life history theory proposes that early-life cues induce highly integrated responses in traits associated with energy partitioning, maturation, reproduction, and aging such that the individual phenotype is adaptively more appropriate to the anticipated environment. Thus, maternal and/or neonatally derived nutritional or endocrine cues suggesting a threatening environment may favour early growth and reproduction over investment in tissue reserve and repair capacity. These may directly affect longevity, as well as prioritise insulin resistance and capacity for fat storage, thereby increasing susceptibility to metabolic dysfunction and obesity. These shifts in developmental trajectory are associated with long-term expression changes in specific genes, some of which may be underpinned by epigenetic processes. This normative process of developmental plasticity may prove to be maladaptive in human environments in transition towards low extrinsic mortality and energy-dense nutrition, leading to the development of an inappropriate phenotype with decreased potential for longevity and/or increased susceptibility to metabolic disease.


Author(s):  
Nicholas M. Grebe ◽  
Steven W. Gangestad

Substantial excitement surrounds the mammalian peptide hormone oxytocin (OT) due to its potential to be a “hormone of love”—and more generally, a biological foundation for the diverse classes of intimate social bonds. Yet, theoretical models have struggled to absorb inconsistent, even contradictory, findings. Evolutionary theory will guide a coherent functional interpretation of the OT system. This chapter focuses on life history theory, a branch of theoretical biology that seeks to identify how natural selection shapes organisms’ efforts to optimally allocate limited resources. Endocrine hormones are important mediators of this process. A review of the psychological and physiological literature regarding OT suggests a number of possible trade-offs negotiated by oxytocinergic activity. This chapter proposes a provisional life history model in which OT is central to the regulation of important but vulnerable social relationships. It outlines implications of this model, addresses a number of caveats, and suggests directions for future research.


2017 ◽  
Vol 74 (12) ◽  
pp. 2059-2072 ◽  
Author(s):  
Zachary S. Feiner ◽  
Stephen C. Chong ◽  
David G. Fielder ◽  
James A. Hoyle ◽  
Carey Knight ◽  
...  

Trade-offs among growth, mortality, and reproduction form the basis of life history theory but may vary among populations owing to local ecological conditions. We examined life history trade-offs driving variation in maturation among 13 yellow perch (Perca flavescens) stocks in the Great Lakes using sex-specific age and length at 50% maturity (A50 and L50, respectively) and probabilistic maturation reaction norm midpoints (Lp50,a). Both sexes exhibited positive correlations between growth and mortality, and faster-growing stocks were mature at younger ages but larger sizes. Male and female A50 and L50 were positively correlated among stocks, but Lp50,a estimates were negatively correlated among stocks, indicating stocks that matured at large sizes for a given age in females matured at smaller age-specific sizes in males. Female Lp50,a estimates were negatively related to growth and mortality, while male Lp50,a estimates were positively related to growth. These results suggest that (i) sex-based life history trade-offs sometimes act to differentially structure maturation schedules in males and females and (ii) males may be less responsive to changes in mortality than females.


2020 ◽  
Author(s):  
Marco Del Giudice ◽  
John D. Haltigan

The field of psychopathology is in a transformative phase, and is witnessing a renewed surge of interest in theoretical models of mental disorders. While many interesting proposals are competing for attention in the literature, they tend to focus narrowly on the proximate level of analysis and lack a broader understanding of biological function. In this paper, we present an integrative framework for mental disorders built on concepts from life history theory, and describe a taxonomy of mental disorders based on its principles, the Fast-Slow-Defense model (FSD). The FSD integrates psychopathology with normative individual differences in personality and behavior, and allows researchers to draw principled distinctions between broad clusters of disorders, as well as identify functional subtypes within current diagnostic categories. Simulation work demonstrates that the model can explain the large-scale structure of comorbidity, including the apparent emergence of a general “p factor” of psychopathology. A life history approach also provides novel integrative insights into the role of environmental risk/protective factors and the developmental trajectories of various disorders. After describing the main features of the FSD model and illustrating its application to the classification of autism and schizophrenia, we juxtapose it with the recent Hierarchical Taxonomy of Psychopathology (HiTOP). We highlight points of difference and similarity, and show how a functional approach helps resolve inconsistencies within a parsimonious account. The FSD model has great potential to further understanding of the development and expression of psychopathology across the lifespan.


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