The heritability of life history strategy: the K-factor, covitality, and personality

Archival data from the MIDUS survey (Brim et al., 2000), a nationally representative sample, on 309 MZ and 333 DZ twin pairs aged 25-74 years were used to test the psychometrics and behavioral genetics of life history strategy. We organized 253 of the originally administered 2,000 questions into 30 scales measuring life history traits (e.g., quality of family relationships and altruism towards kin), medical symptoms (e.g., thyroid problems), personality traits (e.g., neuroticism, extraversion, conscientiousness), and social background (e.g., financial security). A single higher-order factor, indicating a general life history strategy, composed of three lower-order factors, was replicated. Factor analyses were then performed on the genetic variance-covariance matrices. We found that (a) a single higher-order factor explained the preponderance of the genetic correlations among the scales and (b) this higher-order factor was itself 68 percent heritable and accounted for 82 percent of the genetic variance among the three component lower-order factors.     

The heritability of life history strategy: The k‐factor,covitality, and personality

Abstract

Archival data from the MIDUS survey (Brim et al., 2000), a nationally representative sample, on 309 MZ and 333 DZ twin pairs aged 25–74 years were used to test the psychometrics and behavioral genetics of life history strategy. We organized 253 of the originally administered 2,000 questions into 30 scales measuring life history traits (e.g., quality of family relationships and altruism towards kin), medical symptoms (e.g., thyroid problems), personality traits (e.g., neuroticism, extraversion, conscientiousness), and social background (e.g., financial security). A single higher‐order factor, indicating a general life history strategy, composed of three lower‐order factors, was replicated. Factor analyses were then performed on the genetic variance‐covariance matrices. We found that (a) a single higher‐order factor explained the preponderance of the genetic correlations among the scales and (b) this higher‐order factor was itself 68 percent heritable and accounted for 82 percent of the genetic variance among the three component lower‐order factors.     

Using monozygotic twin differences to examine the relationship between parental affection and personality: a life history account

The relationship between maternal and paternal affection, reported in adulthood, and personality was examined using a genetically sensitive research design comparing differences between monozygotic twins. Using life history theory as a framework, it was predicted that differences in maternal and paternal affection would be predictive of differences in personality such that the twin reporting greater maternal and paternal affection would also report a personality profile reflective of a slow life history strategy. Specifically, it was predicted that the twin that reported greater maternal and paternal affection would also score high on the meta-traits of plasticity, stability, and the general factor of personality (GFP). The results supported the hypotheses, with most variance accounted for by the GFP. Additional results suggest that differences in paternal affection exhibit a stronger effect and that stability and plasticity may provide unique information about the association between differences in parental affection and differences in personality. Attachment and parental investment theories offer possible explanations for the findings, although alternative explanations are also proffered. It may also be beneficial for future research using a monozygotic twin difference approach to utilize biometric measures of life history strategy.     

Autistic-like and schizotypal traits in a life history perspective: diametrical associations with impulsivity,sensation seeking,and sociosexual behavior

According to recent theoretical models, autistic-like and schizotypal traits can be regarded as opposite sides of a single continuum of variation in personality and cognition, and may be diametrically associated with individual differences in life history strategies. In this view, schizotypy is a psychological phenotype oriented toward high mating effort and reduced parenting, consistent with a fast life history strategy, whereas autistic-like traits contribute to a slow strategy characterized by reduced mating effort and high parental investment. In this study, we tested the hypothesis that autistic-like and schizotypal traits would be diametrically associated with unrestricted sociosexuality, impulsivity, and sensation seeking (three key behavioral correlates of fast life history strategies in humans) in a sample of 152 young adults (18–38 years). The results were consistent with a diametrical autism–schizotypy axis of individual variation. In line with our hypotheses, autism–schizotypy scores were uniquely associated with individual differences in impulsivity, sensation seeking, and sociosexual behavior, even after controlling for variation in Big Five personality traits. However, we found no significant associations with sociosexual attitude in the present sample. Our findings provide additional support for a life history model of autistic-like and schizotypal traits and demonstrate the heuristic value of this approach in the study of personality and psychopathology.     

Primates got personality,too: Toward an integrative primatology of consistent individual differences in behavior

In recent years, research on animal personality has exploded within the field of behavioral ecology. Consistent individual differences in behavior exist in a wide range of species, and these differences can have fitness consequences and influence several aspects of a species' ecology. In comparison to studies of other animals, however, there has been relatively little research on the behavioral ecology of primate personality. This is surprising given the large body of research within psychology and biomedicine showing that primate personality traits are heritable and linked to health and life history outcomes. In this article, I bring together theoretical perspectives on the ecology and evolution of animal personality with an integrative review of what we know about primate personality from studies conducted on captive, free‐ranging, and wild primates. Incorporating frameworks that emphasize consistency in behavior into primate behavioral ecology research holds promise for improving our understanding of primate behavioral evolution.     

A multi-trait,field-based examination of personality in a semi-aquatic turtle

Studies documenting and quantifying personality traits are common in animal behavior. Such studies often consider the nature of individual variation and personality as correlated with a variety of natural history, physiological, or ecological traits, and therefore consider the importance of personality for strategies in wild systems. Though such studies have contributed markedly to our understanding of the important aspects of personality that may covary with a variety of factors that might affect fitness, much of the research on animal personalities is taxonomically limited. To supplement and compliment the laboratory study of reptile personality, we examined the patterns of multiple personality traits in wild Eastern painted turtles (Chrysemys picta) in the field. We examined patterns of aggression, sociability, and boldness across these traits in different contexts in 103 adult, wild-caught turtles. We found strong correlations both within and among the focal behavioral axes, representing robust evidence for personality in this species. Specifically, we found strong relationships among many measures of aggression, as well as relationships between aggression and our measures of boldness. Finally, we note a tendency for sociability in our turtles, with animals scoring high on sociability showing lower tendency toward aggression. Overall, our study provides robust evidence for correlated suites of behavioral traits, or personality, in a semi-aquatic turtle surveyed in the wild. Future work should continue to expand the range of traits examined to more fully consider the ecological consequences of variation in personality in this and similar species.     

Consistent individual behavior: evidence of personality in black bears

Personality is defined as consistency in individual differences in organismal behavior across time or context, a phenomenon of interest within behavioral and evolutionary ecology. Empirical data have revealed an ever-increasing number and diversity of taxa that display these phenotypic patterns in both wild and captive settings. Moreover, these behavioral traits are frequently linked to wild behavior, life history strategies, and measures of individual fitness. Understanding personality is of particular importance for some animals, such as large carnivores, which may express maladaptive behavior that can lead to conflict with humans. To date, few studies of personality exist on large carnivores and none have investigated the presence of personality in black bears (Ursus americanus). Through focal animal sampling, and open field, novel object, and startle object tests, we investigate the potential for personality in captive black bear cubs. Results indicate the presence of personality, with consistency in behavior across five metrics for the bold-shy axis, and eight sampling events measuring responses for the activity axis. Information presented here reveals the presence of personality in black bear cubs, and may provide a framework for future investigations into relationships of personality with ecology and life history.     

Life history variation among years in a brackish water type of the Ninespine Stickleback, <Emphasis Type="Italic">Pungitius pungitius</Emphasis>

The life history variation in a brackish water type of the Ninespine Stickleback Pungitius pungitius collected over 3 years was studied by examining the strontium (Sr) and calcium (Ca) concentrations in the otoliths. The life histories showed the fish were either brackish water residents or anadromous throughout those years. 74–78% of the fish had the former life history and 22–26% the latter. The composition of each life history was constant throughout the 3 years, and the occurrence of the “anadromous” novel life history found previously is a general phenomenon in this species.     

Early stress predicts age at menarche and first birth,adult attachment,and expected lifespan

Life history theory suggests that in risky and uncertain environments the optimal reproductive strategy is to reproduce early in order to maximize the probability of leaving any descendants at all. The fact that early menarche facilitates early reproduction provides an adaptationist rationale for our first two hypotheses: that women who experience more risky and uncertain environments early in life would have (1) earlier menarche and (2) earlier first births than women who experience less stress at an early age. Attachment theory and research provide the rationale for our second two hypotheses: that the subjective early experience of risky and uncertain environments (insecurity) is (3) part of an evolved mechanism for entraining alternative reproductive strategies contingent on environmental risk and uncertainty and (4) reflected in expected lifespan. Evidence from our pilot study of 100 women attending antenatal clinics at a large metropolitan hospital is consistent with all four hypotheses: Women reporting more troubled family relations early in life had earlier menarche, earlier first birth, were more likely to identify with insecure adult attachment styles, and expected shorter lifespans. Multivariate analyses show that early stress directly affected age at menarche and first birth, affected adult attachment in interaction with expected lifespan, but had no effect on expected lifespan, where its original effect was taken over by interactions between age at menarche and adult attachment as well as age at first birth and adult attachment. We discuss our results in terms of the need to combine evolutionary and developmental perspectives and the relation between early stress in general and father absence in particular. This work was supported by The University of Melbourne Department of Obstetrics and Gynaecology. James S. Chisholm is Professor in the School of Anatomy and Human Biology at the University of Western Australia. He is an anthropologist whose interests lie in the fields of human behavioral biology, evolutionary ecology, life history theory, and parental investment theory, where he focuses on infant social-emotional development, the development of reproductive strategies, and the integration of evolutionary, developmental, and cultural psychology and public health. Julie A. Quinlivan is Associate Professor in Obstetrics and Gynaecology at the University of Melbourne and Head of the Maternity Care Program at the Royal Women’s Hospital, Melbourne. Her interests are teenage pregnancy, domestic violence, child abuse prevention, and high-risk pregnancy. Rodney W. Petersen is Senior Lecturer in Obstetrics and Gynaecology at the University of Melbourne and Senior Consultant in Obstetrics and Gynaecology at the Royal Women’s Hospital and Sunshine Hospital in Melbourne. His interests are in psychosocial aspects of women’s health and cancer. David A. Coall is a Ph.D. student in the School of Anatomy and Human Biology at the University of Western Australia. His main interest lies in the application of evolutionary theory within an epidemiological framework. He is currently working on the synthesis of life history theory, parental investment theory, and parent-offspring conflict theory in exploring factors that influence variation in human birth weight and placental weight.     

Male personality,life‐history strategies and reproductive success in a promiscuous mammal

Recent theoretical work suggests that personality is a component of life history, but links between personality and either age‐dependent reproductive success or life‐history strategy are yet to be established. Using quantitative genetic analyses on a long‐term pedigree we estimated indices of boldness and docility for 105 bighorn sheep rams (Ovis canadensis), born between 1983 and 1999, and compared these indices to their reproductive history from 2 years of age until death. Docility and boldness were highly heritable and negatively genetically correlated. Docile and bold rams survived longer than indocile and shy rams. Docility and boldness had a weak negative effect on reproductive success early in life, but a strong positive effect on older rams. Our findings highlight an important role of personality on reproductive success and suggest that personality could be an important component of life‐history strategy.     

Early life stress, MAOA, and gene-environment interactions predict behavioral disinhibition in children

Several, but not all, studies have shown that the monoamine oxidase A functional promoter polymorphism ( MAOA-LPR ) interacts with childhood adversity to predict adolescent and adult antisocial behavior. However, it is not known whether MAOA-LPR interacts with early life (pre-birth–3 years) stressors to influence behavior in prepubertal children.
The Avon Longitudinal Study of Parents and Children, UK, is a community-representative cohort study of children followed from pre-birth onwards. The impact of family adversity from pre-birth to age 3 years and stressful life events from 6 months to 7 years on behavioral disinhibition was determined in 7500 girls and boys. Behavioral disinhibition measures were: mother-reported hyperactivity and conduct disturbances (Strengths and Difficulties Questionnaire) at ages 4 and 7 years.
In both sexes, exposure to family adversity and stressful life events in the first 3 years of life predicted behavioral disinhibition at age 4, persisting until age 7. In girls, MAOA-LPR interacted with stressful life events experienced from 6 months to 3.5 years to influence hyperactivity at ages 4 and 7. In boys, the interaction of MAOA-LPR with stressful life events between 1.5 and 2.5 years predicted hyperactivity at age 7 years. The low activity MAOA-LPR variant was associated with increased hyperactivity in girls and boys exposed to high stress. In contrast, there was no MAOA-LPR interaction with family adversity.
In a general population sample of prepubertal children, exposure to common stressors from pre-birth to 3 years predicted behavioral disinhibition, and MAOA-LPR – stressful life event interactions specifically predicted hyperactivity.     

Lifespan and age,but not residual reproductive value or condition,are related to behaviour in wild field crickets

Individuals frequently show long‐term consistency in behaviour over their lifetimes, referred to as “personality.” Various models, revolving around the use of resources and how they are valued by individuals, attempt to explain the maintenance of these different behavioural types within a population, and evaluating them is the key for understanding the evolution of behavioural variation. The pace‐of‐life syndrome hypothesis suggests that differences in personalities result from divergent life‐history strategies, with more active/risk‐taking individuals reproducing rapidly but dying young. However, studies of wild animals provide only limited support for key elements of this and related hypotheses, such as a negative relationship between residual reproductive value and activity. Furthermore, alternative models make divergent predictions regarding the relationship between risk‐taking behaviours and variables consistent in the short‐term, such as condition. To test these predictions, we regularly measured willingness to leave a shelter and the activity level of wild adult field crickets (Gryllus campestris) at both short and long intervals over their entire adult lives. We found some support for a pace‐of‐life syndrome influencing personality, as lifespan was negatively related to willingness to leave the shelter and activity. Crickets did not appear to protect their “assets” however, as estimates of residual reproductive value were not related to behaviour. Although there was considerable variance attributed to the short‐term consistency, neither trait was affected by phenotypic condition, failing to support either of the models we tested. Our study confirms that behaviours may covary with some life‐history traits and highlights the scales of temporal consistency that are more difficult to explain.     

Freshman Undergraduate Biology Students�� Difficulties with the Concept of Common Ancestry

All life on earth descended from a single common ancestor that existed several billion years ago; thus, any pair of organisms will have had a common ancestor at some point in their history. This concept is fundamental to an understanding of evolution and phylogeny. Developing an understanding of this concept is an important goal of evolution education and a part of most high school and college biology curricula. This study examines freshman undergraduate biology majors’ understanding and application of the concept of common ancestry. We used a survey that asked students to provide a brief definition of common ancestry and to rate their confidence that different pairs of organisms shared a common ancestor. Our results show that, although many students in our sample could give a satisfactory definition of common ancestry, the overwhelming majority failed to apply their definitions correctly when assessing the likelihood that the pairs of organisms shared common ancestors. Instead, we found that these students do not treat common ancestry as a binary (yes/no) trait, but instead see it as a continuum from less probable to more probable. These students are more likely to think that closely related organisms have a common ancestor than those that are more distantly related and that humans are less likely to be connected to common ancestors than nonhuman organisms. This pattern is highly consistent from student to student and has important implications for teaching evolution.     

Heritability and evolvability of fitness and nonfitness traits: Lessons from livestock

Data from natural populations have suggested a disconnection between trait heritability (variance standardized additive genetic variance, V_A) and evolvability (mean standardized V_A) and emphasized the importance of environmental variation as a determinant of trait heritability but not evolvability. However, these inferences are based on heterogeneous and often small datasets across species from different environments. We surveyed the relationship between evolvability and heritability in >100 traits in farmed cattle, taking advantage of large sample sizes and consistent genetic approaches. Heritability and evolvability estimates were positively correlated (r = 0.37/0.54 on untransformed/log scales) reflecting a substantial impact of V_A on both measures. Furthermore, heritabilities and residual variances were uncorrelated. The differences between this and previously described patterns may reflect lower environmental variation experienced in farmed systems, but also low and heterogeneous quality of data from natural populations. Similar to studies on wild populations, heritabilities for life‐history and behavioral traits were lower than for other traits. Traits having extremely low heritabilities and evolvabilities (17% of the studied traits) were almost exclusively life‐history or behavioral traits, suggesting that evolutionary constraints stemming from lack of genetic variability are likely to be most common for classical “fitness” (cf. life‐history) rather than for “nonfitness” (cf. morphological) traits.     

浮游动物昼夜垂直迁移机理的主要假说及其研究进展

对有关浮游动物昼夜垂直迁移(DVM)机理的实验、假说以及理论模型方面的研究进.展进行了综述。昼夜垂直迁移通常指常规迁移(傍晚上升,拂晓下降),其行为过程不仅影响浮游动物的垂直分布,而且也间接地影响其水平分布及生活史特征,对浮游动物在一定水域的种群维持和补充具有重要的意义。与垂直迁移机理有关的假说主要有光驱动假说、逃避捕食者假说、能量和资源利用假说等,其中逃避捕食者假说已得到大量的实验证实。其理论模型研究一般在两个时间尺度上进行,一个是短期的行为机制研究,另一个从长期的生活史策略的角度考虑。随着实验技术的进步和理论及建模工具的发展,这两个时间尺度的研究正逐渐统一到一个框架下进行。     

Effects of Harsh and Unpredictable Environments in Adolescence on Development of Life History Strategies

The National Longitudinal Study of Adolescent Health data were used to test predictions from life history theory. We hypothesized that (1) in young adulthood an emerging life history strategy would exist as a common factor underlying many life history traits (e.g., health, relationship stability, economic success), (2) both environmental harshness and unpredictability would account for unique variance in expression of adolescent and young adult life history strategies, and (3) adolescent life history traits would predict young adult life history strategy. These predictions were supported. The current findings suggest that the environmental parameters of harshness and unpredictability have concurrent effects on life history development in adolescence, as well as longitudinal effects into young adulthood. In addition, life history traits appear to be stable across developmental time from adolescence into young adulthood.

Living a Fast Life

The current research applied a mid-level evolutionary theory that has been successfully employed across numerous animal species—life history theory—in an attempt to understand the Dark Triad personality trait cluster (narcissism, psychopathy, and Machiavellianism). In Study 1 (N = 246), a measure of life history strategy was correlated with psychopathy, but unexpectedly with neither Machiavellianism nor narcissism. Study 2 (N = 321) replicated this overall pattern of results using longer, traditional measures of the Dark Triad traits and alternative, future-discounting indicators of life history strategy (a smaller-sooner, larger-later monetary dilemma and self-reported risk-taking behaviors). Additional findings suggested two sources of shared variance across the Dark Triad traits: confidence in predicting future outcomes and openness to short-term mating.     

Personality of Wild Male Crested Macaques (Macaca nigra)

Animal personalities, i.e. consistent differences in behavior across time and/or context, have received increased attention of behavioral biologists over the last years. Recent research shows that personalities represent traits on which natural and sexual selection work and which can have substantial fitness consequences. The aim of this study is to establish the personality structure of crested macaque (Macaca nigra) males as foundation for future studies on its adaptive value. We collected behavioral data through focal animal sampling and additionally conducted two sets of playback experiments. Results of a factor analysis on the behavioral data revealed a four factor structure with components we labeled Anxiety, Sociability, Connectedness and Aggressiveness. Results from the experiments revealed an additional and independent Boldness factor but the absence of Neophilia. Overall, this structure resembles other macaque and animal species with the exception of Connectedness, which might be a consequence of the species'' tolerant social style. Our results thus not only form the basis for future studies on the adaptive value of personality in crested macaques but also contribute an important data point for investigating the evolution of personality structure from a comparative perspective by refining, for example, which personality factors characterized the last common ancestor of hominids and macaques.     

Picking personalities apart: estimating the influence of predation,sex and body size on boldness in the guppy Poecilia reticulata

Predation is a strong selective force in most natural systems, potentially fueling evolutionary changes in prey morphology, life history and behaviour. Recent work has suggested that contrasting predation pressures may lead to population differentiation in personality traits. However, there are indications that these personality traits also differ between sexes and not necessarily in a consistent way between populations. We used an integrative approach to quantify boldness (latency to emerge from a shelter) in wild‐caught guppies in relation to predation pressure, population origin, sex and size. In addition we quantified the repeatability of these personality traits. We show that predation regime had significant effects on emergence time. In general, fish from high predation localities emerged sooner from the shelter compared to those from low predation localities. We found strong sex differences; males were significantly bolder than females. The relationship between emergence time and body size was non‐significant in all populations. We discuss what responses to expect from predator‐naïve versus predator‐experienced individuals and how this can be linked to the shyness–boldness continuum.