scholarly journals Harsh environments and "fast" human life histories: What does the theory say?

2015 ◽  
Author(s):  
Ryan Baldini
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Theory ◽  
Environmental Changes ◽  
Human Life ◽  
Life History Evolution ◽  
Harsh Environments ◽  
Harsh Environment ◽  
Common Belief ◽  
Vital Rates

A common belief among human life history researchers is that "harsher" environments - i.e., those with higher mortality rates and resource stress - select for "fast" life histories, i.e. earlier reproduction and faster senescence. I show that these "harsh environments, fast life histories" - or HEFLH - hypotheses are poorly supported by evolutionary theory. First, I use a simple model to show that effects of environmental harshness on life history evolution are incredibly diverse. In particular, small changes in basic but poorly understood variables - e.g., whether and how population density affects vital rates - can cause selection to favor very different life histories. Furthermore, I show that almost all life history theory used to justify HEFLH hypotheses is misapplied in the first place. The reason is that HEFLH hypotheses usually treat plastic responses to heterogeneous environmental conditions within a population, whereas the theory used to justify such hypotheses treat genetic responses to environmental changes across an entire population. Counter-intuitively, the predictions of the former do not generally apply to the latter: the optimal response to a harsh environment within a large heterogeneous environment is not necessarily the optimal strategy of a population uniformly inhabiting the same harsh environment. I discuss these theoretical results in light of the current state of empirical research.

The evolution of childhood as a by-product?

2006 ◽  
Vol 29 (3) ◽  
pp. 288-289
Author(s):  
Peter Kappeler
Keyword(s):  
Life History ◽  
Life Histories ◽  
Nonhuman Primates ◽  
Homo Sapiens ◽  
Human Life ◽  
Life History Evolution ◽  
History Evolution ◽  
Linguistic Skills

The proposition that selective advantages of linguistic skills have contributed to shifts in ontogenetic landmarks of human life histories in early Homo sapiens is weakened by neglecting alternative mechanisms of life history evolution. Moreover, arguments about biological continuity through sweeping comparisons with nonhuman primates do not support various assumptions of this scenario.

scholarly journals From stochastic environments to life histories and back

2009 ◽  
Vol 364 (1523) ◽  
pp. 1499-1509 ◽  
Author(s):  
Shripad Tuljapurkar ◽  
Jean-Michel Gaillard ◽  
Tim Coulson
Keyword(s):  
Life History ◽  
Growth Rates ◽  
Life Histories ◽  
Life History Evolution ◽  
Environmental Stochasticity ◽  
Vital Rates ◽  
Stochastic Growth ◽  
Individual Fitness ◽  
History Evolution ◽  
Average Individual

Environmental stochasticity is known to play an important role in life-history evolution, but most general theory assumes a constant environment. In this paper, we examine life-history evolution in a variable environment, by decomposing average individual fitness (measured by the long-run stochastic growth rate) into contributions from average vital rates and their temporal variation. We examine how generation time, demographic dispersion (measured by the dispersion of reproductive events across the lifespan), demographic resilience (measured by damping time), within-year variances in vital rates, within-year correlations between vital rates and between-year correlations in vital rates combine to determine average individual fitness of stylized life histories. In a fluctuating environment, we show that there is often a range of cohort generation times at which the fitness is at a maximum. Thus, we expect ‘optimal’ phenotypes in fluctuating environments to differ from optimal phenotypes in constant environments. We show that stochastic growth rates are strongly affected by demographic dispersion, even when deterministic growth rates are not, and that demographic dispersion also determines the response of life-history-specific average fitness to within- and between-year correlations. Serial correlations can have a strong effect on fitness, and, depending on the structure of the life history, may act to increase or decrease fitness. The approach we outline takes a useful first step in developing general life-history theory for non-constant environments.

scholarly journals Lack, Skutch, and Moreau: The Early Development of Life-History Thinking

The Condor ◽  
2000 ◽  
Vol 102 (1) ◽  
pp. 3-8 ◽  
Author(s):  
Robert E. Ricklefs
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Theory ◽  
Life History Evolution ◽  
Early Life History ◽  
Nesting Success ◽  
Evolutionary Forces ◽  
Full Development ◽  
The Rich ◽  
David Lack

Abstract Papers by Reginald Moreau, David Lack, and Alexander Skutch published during the 1940s set the stage for the development of thinking about life histories over the following decades. Lack was concerned about the fundamental issue of individual vs. group selection and turned life-history evolution into a battleground for this debate. His monolithic focus on nesting success as a measure of fitness and on food availability as the principal determinant of nesting success obscured the rich empirical background brought to the debate by Skutch and the diverse evolutionary forces envisioned by Moreau. Lack's strong convictions, single-mindedness, and eloquence forced biologists to confront several important problems but also held back the full development of life-history theory until the mid-1960s. Retrospective consideration of these early life-history studies shows how science can progress through a balance of conviction and reflection.

scholarly journals Nutrition shapes life-history evolution across species

2016 ◽  
Vol 283 (1834) ◽  
pp. 20152764 ◽  
Author(s):  
Eli M. Swanson ◽  
Anne Espeset ◽  
Ihab Mikati ◽  
Isaac Bolduc ◽  
Robert Kulhanek ◽  
...  
Keyword(s):  
Life History ◽  
Life Histories ◽  
Host Plants ◽  
Life History Theory ◽  
Life History Evolution ◽  
Sodium Content ◽  
Testis Size ◽  
Eye Size ◽  
History Evolution ◽  
Diet Shifts

Nutrition is a key component of life-history theory, yet we know little about how diet quality shapes life-history evolution across species. Here, we test whether quantitative measures of nutrition are linked to life-history evolution across 96 species of butterflies representing over 50 independent diet shifts. We find that butterflies feeding on high nitrogen host plants as larvae are more fecund, but their eggs are smaller relative to their body size. Nitrogen and sodium content of host plants are also both positively related to eye size. Some of these relationships show pronounced lineage-specific effects. Testis size is not related to nutrition. Additionally, the evolutionary timing of diet shifts is not important, suggesting that nutrition affects life histories regardless of the length of time a species has been adapting to its diet. Our results suggest that, at least for some lineages, species with higher nutrient diets can invest in a range of fitness-related traits like fecundity and eye size while allocating less to each egg as offspring have access to a richer diet. These results have important implications for the evolution of life histories in the face of anthropogenic changes in nutrient availability.

scholarly journals Estimating the evolution of human life history traits in age-structured populations

2014 ◽  
Author(s):  
Ryan Baldini
Keyword(s):  
Life History ◽  
Human Life ◽  
Life History Evolution ◽  
Selection Response ◽  
Structured Populations ◽  
Life History Trait ◽  
Vital Rates ◽  
Structured Population ◽  
Age Structured ◽  
Genetic Contributions

I propose a method that estimates the selection response of all vital rates in an age-structured population. I assume that vital rates are determined by the additive genetic contributions of many loci. The method uses all relatedness information in the sample to inform its estimates of genetic parameters, via an MCMC Bayesian framework. One can use the results to estimate the selection response of any life history trait that is a function of the vital rates, including the age at first reproduction, total lifetime fertility, survival to adulthood, and others. This method closely ties the empirical analysis of life history evolution to dynamically complete models of natural selection, and therefore enjoys some theoretical advantages over other methods. I demonstrate the method on a simulated model of evolution with two age classes. Finally I discuss how the method can be extended to more complicated cases.

scholarly journals Pace of life, predators and parasites: predator-induced life-history evolution in Trinidadian guppies predicts decrease in parasite tolerance

2015 ◽  
Vol 11 (11) ◽  
pp. 20150806 ◽  
Author(s):  
J. F. Stephenson ◽  
C. van Oosterhout ◽  
J. Cable
Keyword(s):  
Life History ◽  
Life Histories ◽  
Large Scale ◽  
Life History Theory ◽  
Poecilia Reticulata ◽  
Life History Evolution ◽  
Predation Pressure ◽  
Pace Of Life ◽  
Evolutionary Response ◽  
Investment In Reproduction

A common evolutionary response to predation pressure is increased investment in reproduction, ultimately resulting in a fast life history. Theory and comparative studies suggest that short-lived organisms invest less in defence against parasites than those that are longer lived (the pace of life hypothesis). Combining these tenets of evolutionary theory leads to the specific, untested prediction that within species, populations experiencing higher predation pressure invest less in defence against parasites. The Trinidadian guppy, Poecilia reticulata , presents an excellent opportunity to test this prediction: guppy populations in lower courses of rivers experience higher predation pressure, and as a consequence have evolved faster life histories, than those in upper courses. Data from a large-scale field survey showed that fish infected with Gyrodactylus parasites were of a lower body condition (quantified using the scaled mass index) than uninfected fish, but only in lower course populations. Although the evidence we present is correlational, it suggests that upper course guppies sustain lower fitness costs of infection, i.e. are more tolerant, than lower course guppies. The data are therefore consistent with the pace of life hypothesis of parasite defence allocation, and suggest that life-history traits mediate the indirect effect of predators on the parasites of their prey.

scholarly journals The importance of population growth and regulation in human life history evolution

2013 ◽  
Author(s):  
Ryan Baldini
Keyword(s):  
Life History ◽  
Population Growth ◽  
Life History Theory ◽  
Human Life ◽  
Life History Evolution ◽  
Structured Populations ◽  
Life History Strategies ◽  
Age Structured ◽  
Zero Population Growth ◽  
Strategy I

Explaining the evolution of human life history characteristics remains an outstanding problem to evolutionary anthropologists. Progress is hindered by common misunderstandings of how selection works in age-structured populations. I review two important results of life history theory related to demography. First, different life history strategies evolve under density-independent and density-dependent population growth. Second, and more poorly appreciated, different kinds of density-dependence also select for different life history strategies; assuming zero population growth alone is insufficient to determine the optimal strategy. I show that these facts are more than methodological niceties by reanalyzing the model by Kaplan et al. (2000) and showing that the results depend strongly on the form of population regulation assumed. This analysis suggests that progress in human life history theory requires better understanding of the demography of our ancestors. I close with a discussion of empirical implications.

A Primer of Life Histories

2021 ◽  
Author(s):  
Jeffrey A. Hutchings
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Theory ◽  
Life History Traits ◽  
Reproductive Effort ◽  
Effective Means ◽  
Academic Experience ◽  
Sustainable Exploitation ◽  
Evolution Of Life ◽  
Opportune Time

Life histories describe how genotypes schedule their reproductive effort throughout life in response to factors that affect their survival and fecundity. Life histories are solutions that selection has produced to solve the problem of how to persist in a given environment. These solutions differ tremendously within and among species. Some organisms mature within months of attaining life, others within decades; some produce few, large offspring as opposed to numerous, small offspring; some reproduce many times throughout their lives while others die after reproducing just once. The exponential pace of life-history research provides an opportune time to engage and re-engage new generations of students and researchers on the fundamentals and applications of life-history theory. Chapters 1 through 4 describe the fundamentals of life-history theory. Chapters 5 through 8 focus on the evolution of life-history traits. Chapters 9 and 10 summarize how life-history theory and prediction has been applied within the contexts of conservation and sustainable exploitation. This primer offers an effective means of rendering the topic accessible to readers from a broad range of academic experience and research expertise.

scholarly journals Age-Appropriate Wisdom? Ethnobiological Knowledge Ontogeny in Pastoralist Mexican Choyeros

2021 ◽  
Author(s):  
Eric Schniter ◽  
Shane Macfarlan ◽  
Juan J. Garcia ◽  
Gorgonio Ruiz‑Campos ◽  
Diego Guevara Beltran ◽  
...  
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Assessment Tool ◽  
Human Life ◽  
Early Adulthood ◽  
Knowledge Assessment ◽  
Baja California Sur ◽  
Age Appropriate ◽  
Age And Sex ◽  
Embodied Capital

We investigate whether age profiles of ethnobiological knowledge developmentare consistent with predictions derived from life history theory about the timing ofproductivity and reproduction. Life history models predict complementary knowledgeprofiles developing across the lifespan for women and men as they experiencechanges in embodied capital and the needs of dependent offspring. We evaluatethese predictions using an ethnobiological knowledge assessment tool developedfor an off-grid pastoralist population known as Choyeros, from Baja California Sur,Mexico. Our results indicate that while individuals acquire knowledge of most dangerousitems and edible resources by early adulthood, knowledge of plants and animalsrelevant to the age and sex divided labor domains and ecologies (e.g., women’shouse gardens, men’s herding activities in the wilderness) continues to develop intomiddle adulthood but to different degrees and at different rates for men and women.As the demands of offspring on parents accumulate with age, reproductive-agedadults continue to develop their knowledge to meet their children’s needs. After controllingfor vision, our analysis indicates that many post-reproductive adults showthe greatest ethnobiological knowledge. These findings extend our understanding ofthe evolved human life history by illustrating how changes in embodied capital andthe needs of dependent offspring predict the development of men’s and women’sethnobiological knowledge across the lifespan.

Life History Strategies

2018 ◽  
pp. 95-126
Author(s):  
Marco Del Giudice
Keyword(s):  
Life History ◽  
Individual Differences ◽  
Life History Theory ◽  
Human Life ◽  
Life History Strategy ◽  
Current Theory ◽  
Life History Strategies ◽  
Extended Model ◽  
Life History Variation ◽  
Basic Model

The chapter introduces the basics of life history theory, the concept of life history strategy, and the fast–slow continuum of variation. After reviewing applications to animal behavior and physiology, the chapter reviews current theory and evidence on individual differences in humans as manifestations of alternative life history strategies. The chapter first presents a “basic model” of human life history–related traits, then advances an “extended model” that identifies multiple cognitive-behavioral profiles within fast and slow strategies. Specifically, it is proposed that slow strategies comprise prosocial/caregiving and skilled/provisioning profiles, whereas fast strategies comprise antisocial/exploitative and seductive/creative profiles. The chapter also reviews potential neurobiological markers of life history variation and considers key methodological issues in this area.

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