Barbara Hagenah Brumbach

Fundamental Dimensions of Environmental Risk : The Impact of Harsh versus Unpredictable Environments on the Evolution and Development of Life History Strategies.

The current paper synthesizes theory and data from the field of life history (LH) evolution to advance a new developmental theory of variation in human LH strategies. The theory posits that clusters of correlated LH traits (e.g., timing of puberty, age at sexual debut and first birth, parental investment strategies) lie on a slow-to-fast continuum; that harshness (externally caused levels of morbidity-mortality) and unpredictability (spatial-temporal variation in harshness) are the most fundamental environmental influences on the evolution and development of LH strategies; and that these influences depend on population densities and related levels of intraspecific competition and resource scarcity, on age schedules of mortality, on the sensitivity of morbidity-mortality to the organism’s resource-allocation decisions, and on the extent to which environmental fluctuations affect individuals versus populations over short versus long timescales. These interrelated factors operate at evolutionary and developmental levels and should be distinguished because they exert distinctive effects on LH traits and are hierarchically operative in terms of primacy of influence. Although converging lines of evidence support core assumptions of the theory, many questions remain unanswered. This review demonstrates the value of applying a multilevel evolutionary-developmental approach to the analysis of a central feature of human phenotypic variation: LH strategy.

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.

The K-factor, Covitality, and personality

We present a psychometric test of life history theory as applied to human individual differences using MIDUS survey data (Brim et al. 2000). Twenty scales measuring cognitive and behavioral dimensions theoretically related to life history strategy were constructed using items from the MIDUS survey. These scales were used to construct a single common factor, the K-factor, which accounted for 70% of the reliable variance. The scales used included measures of personal, familial, and social function. A second common factor, Covitality, was constructed from scales for physical and mental health. Finally, a single general factor, Personality, was constructed from scales for the “Big Five” factors of personality. The K-factor, covitality factor, and general personality factor correlated significantly with each other, supporting the prediction that high K predicts high somatic effort and also manifests in behavioral display. Thus, a single higher-order common factor, the Super-K factor, was constructed that consisted of the K-factor, covitality factor, and personality factor.

Evolutionary Personality Psychology

Multiple selective pressures maintain and increase heritable behavioral variability among individuals across both developmental and evolutionary time: (1) directional social selection favors convergent traits, promoting mutually beneficial cooperative interactions; (2) disruptive social selection favors divergent traits, providing release from within-species competition; (3) genetic diversification responds adaptively to the stochastic (random) characteristics of environmental hazards such as uncontrollable morbidity (disease) and mortality (death); (4) developmental plasticity epigenetically directs development adaptively along different alternative pathways, modifying permanent and stable behavioral dispositions to suit long-term contingencies of survival and reproduction; and (5) behavioral flexibility deploys rapid and reversible short-term adaptive behavioral responses to transient situations.

The Evolutionary Psychology of Human Mate Choice: How Ecology, Genes, Fertility, and Fashion Influence Mating Strategies

Abstract The recent incorporation of sexual selection theories into the rubric of evolutionary psychology has produced an important framework from which to examine human mating behavior. Here we review the extant empirical and theoretical work regarding heterosexual human mating preferences and reproductive strategies. Initially, we review contemporary evolutionary psychologys adaptationism, including the incorporation of modern theories of sexual selection, adaptive genetic variation, and mate choice. Next, we examine womens and mens mating preferences, focusing on the adaptive significance of material, genetic and fertility benefits, and their relationship to environmental characteristics. Following this, we consider human mate choice in relation to non-adaptive preferences. This discussion ends with a look at context effects for individual differences in mate-preferences and reproductive strategies.

Sex, aggression, and life history strategy

We agree that sexual selection is a more comprehensive explanation for sex differences in direct aggression than social role theory, which is an unparsimonious and vestigial remnant of human exceptionalism. Nevertheless, Archer misses several opportunities to put the theoretical predictions made by himself and by others into direct competition in a way that would further the interests of strong inference.