On the Psychometric Study of Human Life History Strategies

Childhood environmental harshness and unpredictability negatively predict eHealth literacy through fast life-history strategy

Background

eHealth literacy-the ability to obtain, understand, evaluate, and use health information from the Internet-is important to maintaining and improving personal health. Prior research found that people differ notably in the levels of eHealth literacy, and this study tests a theoretical account of some of those individual differences. Drawing on life history theory, we propose that low eHealth literacy is partly the outcome of people adopting a resource-allocation strategy emphasizing early and fast reproduction, namely, a fast life-history strategy.

Methods

We conducted a cross-sectional survey study (N = 1,036) that measured Chinese adult respondents' eHealth literacy, childhood environmental harshness and unpredictability, and fast life-history strategy. Covariates included health-information seeking online, self-rated health, sex, age, education level, and monthly income.

Results

Supporting a life-history explanation of eHealth literacy, childhood environmental harshness and unpredictability negatively predicted eHealth literacy through fast life-history strategy and mainly the insight-planning-control dimension of it. Harshness, not unpredictability, also directly and negatively predicted eHealth literacy after fast life-history strategy was controlled for.

Conclusion

Our findings suggest that the psychological mechanisms associated with human life-history strategies produce at least some of the individual differences in levels of eHealth literacy, including those related to neuroticism, socioeconomic status, self-rated health and social capital. Thus, a possible way to increase future generation's eHealth literacy and thereby their health is to reduce the harshness and unpredictability of the environment in which they grow up, thereby making them more likely to adopt a relatively slow life-history in their adulthood.

Testing Environmental Effects on Age at Menarche and Sexual Debut within a Genetically Informative Twin Design

Life-history-derived models of female sexual development propose menarche timing as a key regulatory mechanism driving subsequent sexual behavior. The current research utilized a twin subsample of the National Longitudinal Study of Adolescent to Adult Health (Add Health; n = 514) to evaluate environmental effects on timings of menarche and sexual debut, as well as address potential confounding of these effects within a genetically informative design. Results show mixed support for each life history model and provide little evidence rearing environment is important in the etiology of individual differences in age at menarche. This research calls into question the underlying assumptions of life-history-derived models of sexual development and highlights the need for more behavior genetic research in this area.

A Double-Track Pathway to Fast Strategy in Humans and Its Personality Correlates

The fast-slow paradigm of life history (LH) focuses on how individuals grow, mate, and reproduce at different paces. This paradigm can contribute substantially to the field of personality and individual differences provided that it is more strictly based on evolutionary biology than it has been so far. Our study tested the existence of a fast-slow continuum underlying indicators of reproductive effort-offspring output, age at first reproduction, number and stability of sexual partners-in 1,043 outpatients with healthy to severely disordered personalities. Two axes emerged reflecting a double-track pathway to fast strategy, based on restricted and unrestricted sociosexual strategies. When rotated, the fast-slow and sociosexuality axes turned out to be independent. Contrary to expectations, neither somatic effort-investment in status, material resources, social capital, and maintenance/survival-was aligned with reproductive effort, nor a clear tradeoff between current and future reproduction was evident. Finally, we examined the association of LH axes with seven high-order personality pathology traits: negative emotionality, impulsivity, antagonism, persistence-compulsivity, subordination, and psychoticism. Persistent and disinhibited subjects appeared as fast-restricted and fast-unrestricted strategists, respectively, whereas asocial subjects were slow strategists. Associations of LH traits with each other and with personality are far more complex than usually assumed in evolutionary psychology.

Too Many Males or Too Many Females? Classroom Sex Ratio, Life History Strategies and Risk-Taking Behaviors

Prior research finds that sex ratio, defined as the proportion of males and females in a given context, is related to engagement in risk-taking behaviors. However, most research operationalizes sex ratio at a local context (e.g., regional or county), which fails to reflect with precision the sex ratios contexts of individuals at a closer level. Furthermore, the relationship between sex ratio and risk-taking behaviors may be affected by individuals’ life history strategy, with previous studies showing fast life history strategies linked to risk-taking behaviors, compared to slow life history strategies. The present study analyzes the relationship between classroom sex ratio and risk-taking behaviors and the interaction between classroom sex ratio and life history strategy in adolescents. The sample comprised 1214 participants nested in 57 classrooms, 49.75% females, 91.5% Spanish and a mean age of 16.15 years (SD = 1.23, range 14–21). Results from multilevel modeling showed a negative relation between classroom sex ratio and risk-taking behaviors in female adolescents with faster life history strategy. By contrast, classroom sex ratio in male adolescents related positively to risk-taking behaviors but did not interact with life history strategy. These findings underscore the importance of studying proximate sex ratio on risk-taking behaviors in adolescents and underline its potential influence in the development and expression of life history strategies.

Why and how does early adversity influence development? Toward an integrated model of dimensions of environmental experience

Two extant frameworks - the harshness-unpredictability model and the threat-deprivation model - attempt to explain which dimensions of adversity have distinct influences on development. These models address, respectively, why, based on a history of natural selection, development operates the way it does across a range of environmental contexts, and how the neural mechanisms that underlie plasticity and learning in response to environmental experiences influence brain development. Building on these frameworks, we advance an integrated model of dimensions of environmental experience, focusing on threat-based forms of harshness, deprivation-based forms of harshness, and environmental unpredictability. This integrated model makes clear that the why and the how of development are inextricable and, together, essential to understanding which dimensions of the environment matter. Core integrative concepts include the directedness of learning, multiple levels of developmental adaptation to the environment, and tradeoffs between adaptive and maladaptive developmental responses to adversity. The integrated model proposes that proximal and distal cues to threat-based and deprivation-based forms of harshness, as well as unpredictability in those cues, calibrate development to both immediate rearing environments and broader ecological contexts, current and future. We highlight actionable directions for research needed to investigate the integrated model and advance understanding of dimensions of environmental experience.

Borderline Personality Disorder in a "Life History Theory" Perspective: Evidence for a Fast "Pace-of-Life-Syndrome"

"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.

Advancing the Psychometric Study of Human Life History Indicators : K Does Not Measure Life History Speed, but Theory and Evidence Suggest It Deserves Further Attention

In this article we attend to recent critiques of psychometric applications of life history (LH) theory to variance among humans and develop theory to advance the study of latent LH constructs. We then reanalyze data (n = 4,244) previously examined by Richardson et al. (Evolutionary Psychology, 15(1), 2017, https://doi.org/10.1177/1474704916666840 to determine whether (a) previously reported evidence of multidimensionality is robust to the modeling approach employed and (b) the structure of LH indicators is invariant by sex. Findings provide further evidence that a single LH dimension is implausible and that researchers should cease interpreting K-factor scores as empirical proxies for LH speed. In contrast to the original study, we detected a small inverse correlation between mating competition and Super-K that is consistent with a trade-off. Tests of measurement invariance across the sexes revealed evidence of metric invariance (i.e., equivalence of factor loadings), consistent with the theory that K is a proximate cause of its indicators; however, evidence of partial scalar invariance suggests use of scores likely introduces bias when the sexes are compared. We discuss limitations and identify approaches that researchers may use to further evaluate the validity of the K-factor and other applications of LH to human variation.

Live fast, die young and sleep later: Life history strategy and human sleep behavior

Background and objectives

Life History Theory (LHT) describes trade-offs that organisms make with regard to three investment pathways: growth, maintenance and reproduction. In light of the reparative functions of sleep, we examine sleep behaviors and corresponding attitudes as proximate manifestations of an individual's underlying relative prioritization of short-term reproduction versus long-term maintenance.

Methodology

We collected survey data from 568 participants across two online studies having different participant pools. We use a mixture of segmented and hierarchical regression models, structural equation modeling and machine learning to infer relationships between sleep duration/quality, attitudes about sleep and biodemographic/psychometric measures of life history strategy (LHS).

Results

An age-mediated U- or V-shaped relationship appears when LHS is plotted against habitual sleep duration, with the fastest strategies occupying the sections of the curve with the highest mortality risk: < 6.5 hr (short sleep) and > 8.5 hr (long sleep). LH 'fastness' is associated with increased sleepiness and worse overall sleep quality: delayed sleep onset latency, more wakefulness after sleep onset, higher sleep-wake instability and greater sleep duration variability. Hedonic valuations of sleep may mediate the effects of LHS on certain sleep parameters.

Conclusions and implications

The costs of deprioritizing maintenance can be parameterized in the domain of sleep, where 'life history fastness' corresponds with sleep patterns associated with greater senescence and mortality. Individual differences in sleep having significant health implications can thus be understood as components of lifelong trajectories likely stemming from calibration to developmental circumstances. Relatedly, hedonic valuations of sleep may constitute useful avenues for non-pharmacological management of chronic sleep disorders.Lay Summary: Sleep is essential because it allows the body to repair and maintain itself. But time spent sleeping is time that cannot be spent doing other things. People differ in how much they prioritize immediate rewards, including sociosexual opportunities, versus long-term goals. In this research, we show that individual differences in sleep behaviors, and attitudes toward sleep, correspond with psychological and behavioral differences reflecting such differing priorities. Orientation toward sleep can thus be understood as part of the overall lifetime strategies that people pursue.

Psychometric evaluation of the short form of the Arizona Life History Battery (K-SF-42): A revised Chinese version for emerging adults

Life history (LH) strategies explain how organisms adapt to the environment and make the best use of their resources to fulfill bodily maintenance, growth, reproduction and other functions. The K-SF-42 is a short version of the 199-item Arizona Life History Battery for assessing seven different domains of LH strategies. This article aims to evaluate the psychometric properties of a Chinese version of the K-SF-42. We recruited 1,016 Chinese university students, who aged 16 to 28 years old (M age = 19.47, SD = 1.17) to participant in an anonymous questionnaire. Results of the confirmatory factor analysis supported the second-order six-factor model (except romantic partner attachment), and the scale and subscales of such measurement displayed good internal consistencies. With the exception of religiosity, all of the subscales showed significant positive correlations with a brief unidimensional measure of LH strategies (i.e., the Mini-K). The criterion-related validity of the scale was further supported by the association between its higher score (suggesting slower LH strategies) and the lower levels of childhood harshness and unpredictability. This study provided evidence for the satisfactory applicability of the Chinese version of the K-SF-42 to a Chinese population and contributed to the further investigation of the LH strategies' mechanisms underlying human behavior across cultures.

Do Criminals Live Faster Than Soldiers and Firefighters? : A Comparison of Biodemographic and Psychosocial Dimensions of Life History Theory

A high risk of morbidity-mortality caused by a harsh and unpredictable environment is considered to be associated with a fast life history (LH) strategy, commonly linked with criminal behavior. However, offenders are not the only group with a high exposure to extrinsic morbidity-mortality. In the present study, we investigated the LH strategies employed by two groups of Polish men: incarcerated offenders (N = 84) as well as soldiers and firefighters (N = 117), whose professions involve an elevated risk of injury and premature death. The subjects were asked to complete the Mini-K (used as a psychosocial LH indicator) and a questionnaire which included a number of biodemographic LH variables. Although biodemographic and psychosocial LH indicators should be closely linked with each other, the actual connection between them is unclear. Thus, this study was driven by two aims: comparing LH strategies in two groups of men with a high risk of premature morbidity-mortality and investigating the relationship between the biodemographic and psychosocial LH dimensions. The study showed that incarcerated men employed faster LH strategies than soldiers and firefighters, but only in relation to biodemographic variables (e.g., number of siblings, age of sexual initiation, life expectancy). No intergroup differences emerged regarding psychosocial LH indicators. Moreover, the correlation analysis showed a weak association between biodemographic and psychosocial LH indicators. The results strengthen the legitimacy of incorporating biodemographic LH traits into research models and indicate the need for further research on the accuracy of the Mini-K. The possible explanations for the intergroup differences in LH strategies are discussed.

The Structure of the Mini-K and K-SF-42 : A Psychological Network Approach

Life history theory is a fruitful source of testable hypotheses about human individual differences. However, this field of study is beset by unresolved debates about basic concepts and methods. One of these controversies concerns the usefulness of instruments that purport to tap a unidimensional life history (LH) factor based on a set of self-reported personality, social, and attitudinal variables. Here, we take a novel approach to analyzing the psychometrics of two variants of the Arizona Life History Battery: the Mini-K and the K-SF-42. Psychological network analysis generates models in which psychological variables (thoughts, feelings, or behaviors) comprise the nodes of a network, while partial correlation coefficients between these variables comprise the edges of the network. Centrality indices (strength, closeness, and betweenness) operationalize each node's importance based on the pattern of the connections in which that node plays a role. Because childhood environments are hypothesized to influence adult LH, we tested the hypothesis that among the Mini-K items, and the K-SF-42 scales, those that tap relationships with parents are central to the networks (pairwise Markov random fields) constructed from these instruments. In an MTurk sample and an undergraduate sample that completed the Mini-K, and an MTurk sample that completed the K-SF-42, this hypothesis was falsified. Indeed, the "relationships with parents" items were among the most peripheral in all three networks. We propose that network analysis, as an alternative to latent variable modeling, offers considerable potential to test hypotheses about the input-output mappings of specific evolved psychological mechanisms.

Structure and longitudinal invariance of the Short Alcohol and Alcohol Problems Perception Questionnaire

Many studies have employed the Short Alcohol Attitudes Problem Perception Questionnaire (SAAPPQ) to measure professionals' attitudes toward working with people experiencing alcohol problems. However, research has not confirmed the internal structure of the SAAPPQ, leaving open the possibility that scale scores are not valid empirical proxies for underlying attitudes. It is also unclear if measurement invariance holds over time or across groups. This is an important gap in light of evidence that (a) experiences can change the structure of scales and (b) structures of some popular scales differ dramatically between groups. Thus, measurement bias may confound comparisons of composite SAAPPQ scores between measurement occasions or groups. To address these gaps in the literature, we conducted a longitudinal examination of the psychometrics of the SAAPPQ using data from 241 human services professionals-in-training. We found a four-factor structure, rather than the previously reported five factors. Configural, metric, and a strong degree of scalar invariance held longitudinally. Few factor intercorrelations were significant at time one and they strengthened over time, suggesting that the SAAPPQ should not be aggregated at higher-order levels (i.e., global scores should not be used). Findings suggest four SAAPPQ subscale scores may be used as valid proxies for attitudes toward alcohol users; however, additional confirmatory studies are needed to ensure that measurement bias does not compromise inferences based on SAAPPQ scores.

Using syndemic theory to understand food insecurity and diet-related chronic diseases

Syndemic Theory (ST) provides a framework to examine mutually enhancing diseases/health issues under conditions of social inequality and inequity. ST has been used in multiple disciplines to address interacting infectious diseases, noncommunicable diseases, and mental health conditions. The theory has been critiqued for its inability to measure disease interactions and their individual and combined health outcomes. This article reviews literature that strongly suggests a syndemic between food insecurity (FI) and diet-related chronic diseases (DRCDs), and proposes a model to measure the extent of such interaction. The article seeks to: (1) examine the potential syndemic between FI and DRCDs; (2) illustrate how the incorporation of Life History Theory (LHT), into a syndemic framework can help to highlight critical lifeperiods when FI-DRCD interactions result in adverse health outcomes; (3) discuss the use of mixed methods to identify and measure syndemics to enhance the precision and predictive power of ST; and (4) propose an analytical model for the examination of the FI-DRCD syndemic through the life course. The proposed model is more relevant now given the significant increase in FI globally as a result of the ongoing COVID-19 pandemic. The differential impact that the pandemic appears to have among various age groups and by other demographic factors (e.g., race, gender, income) offers an opportunity to examine the potential FI-DRCD syndemic under the lens of LHT.

Life-history theory in psychology and evolutionary biology: one research programme or two?

The term ‘life-history theory’ (LHT) is increasingly often invoked in psychology, as a framework for integrating understanding of psychological traits into a broader evolutionary context. Although LHT as presented in psychology papers (LHT-P) is typically described as a straightforward extension of the theoretical principles from evolutionary biology that bear the same name (LHT-E), the two bodies of work are not well integrated. Here, through a close reading of recent papers, we argue that LHT-E and LHT-P are different research programmes in the Lakatosian sense. The core of LHT-E is built around ultimate evolutionary explanation, via explicit mathematical modelling, of how selection can drive divergent evolution of populations or species living under different demographies or ecologies. The core of LHT-P concerns measurement of covariation, across individuals, of multiple psychological traits; the proximate goals these serve; and their relation to childhood experience. Some of the links between LHT-E and LHT-P are false friends. For example, elements that are marginal in LHT-E are core commitments of LHT-P, and where explanatory principles are transferred from one to the other, nuance can be lost in transmission. The methodological rules for what grounds a prediction in theory are different in the two cases. Though there are major differences between LHT-E and LHT-P at present, there is much potential for greater integration in the future, through both theoretical modelling and further empirical research.

This article is part of the theme issue ‘Life history and learning: how childhood, caregiving and old age shape cognition and culture in humans and other animals’.

Developmental Adaptation to Stress: An Evolutionary Perspective

The assumption that early stress leads to dysregulation and impairment is widespread in developmental science and informs prevailing models (e.g., toxic stress). An alternative evolutionary–developmental approach, which complements the standard emphasis on dysregulation, proposes that early stress may prompt the development of costly but adaptive strategies that promote survival and reproduction under adverse conditions. In this review, we survey this growing theoretical and empirical literature, highlighting recent developments and outstanding questions. We review concepts of adaptive plasticity and conditional adaptation, introduce the life history framework and the adaptive calibration model, and consider how physiological stress response systems and related neuroendocrine processes may function as plasticity mechanisms. We then address the evolution of individual differences in susceptibility to the environment, which engenders systematic person–environment interactions in the effects of stress on development. Finally, we discuss stress-mediated regulation of pubertal development as a case study of how an evolutionary–developmental approach can foster theoretical integration.

Life History Theory and Recovery From Substance Use Disorder

Recovery has emerged as an important paradigm in addictions treatment but the field has yet to achieve consensus on how it should be defined and measured. The recovery construct has been extended beyond sustained reductions in use or abstinence to enhancements in global health/well-being and also prosocial community reintegration. However, few studies have included these broader domains in their measurement of recovery and few scientific theories have been advanced to explain why reductions in substance use occasion these broader life changes. This article applies life history theory to recovery for the first time to help define recovery, advance recovery measurement, and explain why broad change across multiple life domains should facilitate sustained recovery progress. We conclude with a discussion of future directions and challenges for future research informed by our life history framework for recovery.

Testing the indirect effects of somatic and parental effort on stress: the roles of worldviews and coping strategies

Life history theory (LHT) is a mid-level theory from evolutionary biology. LHT, adapted to humans, assumes that individuals can be placed along a single continuum of LH strategies referred to as the slow-to-fast LH continuum: faster life history strategists score higher on mating effort and lower on somatic and parental effort. In the present study we examine the hypothesis that worldview and coping strategies are mediators between somatic and parental effort (SPE) and current perceived stress. 226 participants completed a set of instruments: Mini-K, the World Assumptions Scale, Brief COPE, and the Perceived Stress Scale. In order to test the hypotheses about mediators, Structural Equation Modeling (SEM) was used. The results from the current study showed that individuals allocating their own resources to SPE experienced lower current stress, and felt positive about the benevolence and meaningfulness of the world as well as the worthiness of the self. A more complex linkage was also revealed: individuals displaying SPE endorsed stronger beliefs about self-worth, which in turn was associated with a lower tendency to use disengagement coping and which again translated into a lower level of perceived stress. Furthermore, females investing in SPE maintained a higher level of belief in the meaningfulness of the world, which translated into a higher tendency to use external support for coping.

Mating Effort Predicts Human Menstrual Cycle Frequency

The human menstrual cycle is characterized by substantial variability both within and between women. Here, we sought to account for such variability by examining whether human menstrual cycle frequency varies as a function of the projected fitness payoffs associated with investment in mating effort. We used structural equation modeling to test the prediction that women whose environmental conditions or life histories favor heavier investment in mating effort would have shorter, more regular cycles. Results supported our hypothesis, revealing that women who project more mating success and have faster life history strategies exhibit greater mating effort and shorter, more regular menstrual cycles. An alternative model that specified cycle frequency as a predictor of mating effort was a poor fit for the data, lending support for the hypothesized directionality of the path between these variables. Together, these results provide some of the first empirical evidence that the length and regularity of the human menstrual cycle may be calibrated to investment in mating effort.

Measuring the Unmeasurable : The Psychometrics of Life History Strategy

Within evolutionary biology, life-history theory is used to explain cross-species differences in allocation strategies regarding reproduction, maturation, and survival. Behavioral scientists have recently begun to conceptualize such strategies as a within-species individual characteristic that is predictive of behavior. Although life history theory provides an important framework for behavioral scientists, the psychometric approach to life-history strategy measurement—as operationalized by K-factors—involves conceptual entanglements. We argue that current psychometric approaches attempting to identify K-factors are based on an unwarranted conflation of functional descriptions and proximate mechanisms—a conceptual mix-up that may generate unviable hypotheses and invites misinterpretation of empirical findings. The assumptions underlying generic psychometric methodology do not allow measurement of functionally defined variables; rather these methods are confined to Mayr’s proximate causal realm. We therefore conclude that K-factor scales lack validity, and that life history strategy cannot be identified with psychometrics as usual. To align theory with methodology, suggestions for alternative methods and new avenues are proposed.

Associations between psychometrically assessed life history strategy and daily behavior: data from the Electronically Activated Recorder (EAR)

Life history theory has generated cogent, well-supported hypotheses about individual differences in human biodemographic traits (e.g., age at sexual maturity) and psychometric traits (e.g., conscientiousness), but little is known about how variation in life history strategy (LHS) is manifest in quotidian human behavior. Here I test predicted associations between the self-report Arizona Life History Battery and frequencies of 12 behaviors observed over 72 h in 91 US college students using the Electronically Activated Recorder (EAR), a method of gathering periodic brief audio recordings as participants go about their daily lives. Bayesian multi-level aggregated binomial regression analysis found no strong associations between ALHB scores and behavior frequencies. One behavior, presence at amusement venues (bars, concerts, sports events) was weakly positively associated with ALHB-assessed slow LHS, contrary to prediction. These results may represent a challenge to the ALHB's validity. However, it remains possible that situational influences on behavior, which were not measured in the present study, moderate the relationships between psychometrically-assessed LHS and quotidian behavior.

The Evolutionary Life History Model of Externalizing Personality: Bridging Human and Animal Personality Science to Connect Ultimate and Proximate Mechanisms Underlying Aggressive Dominance, Hostility, and Impulsive Sensation Seeking

The present work proposes an evolutionary model of externalizing personality that defines variation in this broad psychobiological phenotype resulting from genetic influences and a conditional adaptation to high-risk environments with high extrinsic morbidity-mortality. Due to shared selection pressure, externalizing personality is coadapted to fast life history strategies and maximizes inclusive fitness under adverse environmental conditions by governing the major trade-offs between reproductive versus somatic functions, current versus future reproduction, and mating versus parenting efforts. According to this model, externalizing personality is a regulatory device at the interface between the individual and its environment that is mediated by 2 overlapping psychobiological systems, that is, the attachment and the stress-response system. The attachment system coordinates interpersonal behavior and intimacy in close relationships and the stress-response system regulates the responsivity to environmental challenge and both physiological and behavioral reactions to stress. These proximate mechanisms allow for the integration of neuroendocrinological processes underlying interindividual differences in externalizing personality. Hereinafter I further discuss the model's major implications for personality psychology, psychiatry, and public health policy.

Brief Self-Report Scales Assessing Life History Dimensions of Mating and Parenting Effort

Life history theory (LHT) is a powerful evolutionary framework for understanding physiological, psychological, and behavioral variation both between and within species. Researchers and theorists are increasingly integrating LHT into evolutionary psychology, as it provides a strong foundation for research across many topical areas. Human life history variation has been represented in psychological and behavioral research in several ways, including indicators of conditions in the developmental environment, indicators of conditions in the current environment, and indicators of maturation and life milestones (e.g., menarche, initial sexual activity, first pregnancy), and in self-report survey scale measures. Survey scale measures have included constructs such as time perspective and future discounting, although the most widely used index is a constellation of indicators assessing the K-factor, thought to index general life history speed (from fast to slow). The current project examined the utility of two brief self-report survey measures assessing the life history dimensions of mating effort and parenting effort with a large undergraduate sample in the United States. Consistent with the theory, items reflected two inversely related dimensions. In regressions including the K-factor, the Mating Effort Scale proved to be a powerful predictor of other constructs and indicators related to life history variation. The Parenting Effort Scale had less predictive power overall, although it explained unique variance across several constructs and was the only unique predictor of the number of long-term (serious and committed) relationships. These scales may be valuable additions to self-report survey research projects examining life history variation.

The Psychometric Evaluation of Human Life Histories

A recent critique of Copping, Campbell, and Muncer raised several issues concerning the validity of psychometric assessment techniques in the study of life history (LH) strategies. In this reply, some of our key concerns about relying on aggregated psychometric measures are explained, and we raise questions generally regarding the use of higher order factor structures. Responses to some of the statistical issues raised by Figueredo et al. are also detailed. We stand by our original conclusions and call for more careful consideration of instruments used to evaluate hypotheses derived from LH theory.