Human Life History Strategies: Calibrated to External or Internal Cues?

Human life history (LH) strategies are theoretically regulated by developmental exposure to environmental cues that ancestrally predicted LH-relevant world states (e.g., risk of morbidity-mortality). Recent modeling work has raised the question of whether the association of childhood family factors with adult LH variation arises via (i) direct sampling of external environmental cues during development and/or (ii) calibration of LH strategies to internal somatic condition (i.e., health), which itself reflects exposure to variably favorable environments. The present research tested between these possibilities through three online surveys involving a total of over 26,000 participants. Participants completed questionnaires assessing components of self-reported environmental harshness (i.e., socioeconomic status, family neglect, and neighborhood crime), health status, and various LH-related psychological and behavioral phenotypes (e.g., mating strategies, paranoia, and anxiety), modeled as a unidimensional latent variable. Structural equation models suggested that exposure to harsh ecologies had direct effects on latent LH strategy as well as indirect effects on latent LH strategy mediated via health status. These findings suggest that human LH strategies may be calibrated to both external and internal cues and that such calibrational effects manifest in a wide range of psychological and behavioral phenotypes

Hormonal and morphological predictors of women’s body attractiveness

Does women’s body attractiveness predict indices of reproductive capacity? Prior research has provided evidence that large breast size and low waist-to-hip ratio (WHR) are positively associated with women’s estrogen and progesterone concentrations, but no previous studies appear to have directly tested whether ratings of women\u27s body attractiveness are predicted by higher concentrations of ovarian hormones measured across broad regions of the menstrual cycle. Here, we collected daily saliva samples across 1–2 menstrual cycles from a sample of young women; assayed the samples for estradiol, progesterone, and testosterone; obtained anthropometric measurements of the women’s bodies; and also obtained attractiveness ratings of the women’s bodies from photographs of them taken in standardized clothing with faces obscured. Contrary to previous research, mean hormone concentrations were uncorrelated with breast size and WHR. Body mass index (BMI) was a very strong negative predictor of body attractiveness ratings, similar to previous findings. Zero-order associations between women’s mean hormone concentrations and mean attractiveness ratings were not significant; however, after controlling for BMI, attractiveness ratings were independently and positively associated with both estradiol and testosterone concentrations. Discussion focuses on the implications of these findings for whether attractiveness assessment mechanisms are specialized for the detection of cues of differential fecundity in young women’s bodies

Dissection of QTL effects for root traits using a chromosome arm-specific mapping population in bread wheat

A high-resolution chromosome arm-specific mapping population was used in an attempt to locate/detect gene(s)/QTL for different root traits on the short arm of rye chromosome 1 (1RS) in bread wheat. This population consisted of induced homoeologous recombinants of 1RS with 1BS, each originating from a different crossover event and distinct from all other recombinants in the proportions of rye and wheat chromatin present. It provides a simple and powerful approach to detect even small QTL effects using fewer progeny. A promising empirical Bayes method was applied to estimate additive and epistatic effects for all possible marker pairs simultaneously in a single model. This method has an advantage for QTL analysis in minimizing the error variance and detecting interaction effects between loci with no main effect. A total of 15 QTL effects, 6 additive and 9 epistatic, were detected for different traits of root length and root weight in 1RS wheat. Epistatic interactions were further partitioned into inter-genomic (wheat and rye alleles) and intra-genomic (rye–rye or wheat–wheat alleles) interactions affecting various root traits. Four common regions were identified involving all the QTL for root traits. Two regions carried QTL for almost all the root traits and were responsible for all the epistatic interactions. Evidence for inter-genomic interactions is provided. Comparison of mean values supported the QTL detection

Data from: Cues of upper body strength account for most of the variance in men’s bodily attractiveness

Evolution equips sexually reproducing species with mate choice mechanisms that function to evaluate the reproductive consequences of mating with different individuals. Indeed, evolutionary psychologists have shown that women’s mate choice mechanisms track many cues of men’s genetic quality and ability to invest resources in the woman and her offspring. One variable that predicted both a man’s genetic quality and his ability to invest is the man’s formidability (i.e. fighting ability or resource holding power/potential). Modern women, therefore, should have mate choice mechanisms that respond to ancestral cues of a man’s fighting ability. One crucial component of a man’s ability to fight was his upper body strength. Here we test how important physical strength is to men’s bodily attractiveness. Three sets of photographs of men’s bodies were shown to raters who estimated either their physical strength or their attractiveness. Estimates of physical strength determined over 70% of men’s bodily attractiveness. Additional analyses showed that tallness and leanness were also favored, and – along with estimates of physical strength – accounted for 80% of men’s bodily attractiveness. Contrary to popular theories of men’s physical attractiveness, there was no evidence of a non-linear effect; the strongest men were the most attractive in all samples

Data from: Cues of upper body strength account for most of the variance in men’s bodily attractiveness

Evolution equips sexually reproducing species with mate choice mechanisms that function to evaluate the reproductive consequences of mating with different individuals. Indeed, evolutionary psychologists have shown that women’s mate choice mechanisms track many cues of men’s genetic quality and ability to invest resources in the woman and her offspring. One variable that predicted both a man’s genetic quality and his ability to invest is the man’s formidability (i.e. fighting ability or resource holding power/potential). Modern women, therefore, should have mate choice mechanisms that respond to ancestral cues of a man’s fighting ability. One crucial component of a man’s ability to fight was his upper body strength. Here we test how important physical strength is to men’s bodily attractiveness. Three sets of photographs of men’s bodies were shown to raters who estimated either their physical strength or their attractiveness. Estimates of physical strength determined over 70% of men’s bodily attractiveness. Additional analyses showed that tallness and leanness were also favored, and – along with estimates of physical strength – accounted for 80% of men’s bodily attractiveness. Contrary to popular theories of men’s physical attractiveness, there was no evidence of a non-linear effect; the strongest men were the most attractive in all samples

The Extraversion Continuum in Evolutionary Perspective: A Review of Recent Theory and Evidence

We review research on the ultimate and proximate origins of variation along the extraversion continuum. After describing the cost-benefit tradeoffs that may have maintained variation in extraversion over human evolution, we consider the evidence bearing on multiple distinct evolutionary hypotheses regarding the causal underpinnings of such variation. On the basis of the reviewed evidence, we argue that fluctuating selection on specific polymorphic genotypes is unlikely to explain the origins of individual differences in extraversion. Rather, adaptively patterned variation in extraversion is likely orchestrated primarily by facultative adaptations designed to calibrate behavioral strategies to cues available in ontogeny. For example, emerging research supports the hypothesis that extraversion may be “reactively heritable” by virtue of its calibration to heritable condition-dependent phenotypic features – which in turn helps explain extraversion’s genetic variance, as well as its consistent positive association with reproductive success. Finally, evidence suggests that some of the inter-individual variance in extraversion is fundamentally noisy, arising as a side effect of mutation–selection balance or pleiotropic polymorphisms maintained via pathogen–host coevolution. If correct, these conclusions indicate that future research should focus on elucidating the facultative adaptations designed to regulate the production of behaviors falling on the extraversion continuum

Adaptive Personality Calibration in a Human Society: Effects of Embodied Capital on Prosocial Traits

Evolutionary theories of personality origins have stimulated much empirical research in recent years, but pertinent data from small-scale human societies have been in short supply. We investigate adaptively patterned personality variation among Tsimane’ forager-horticulturalists. Based on a consideration of cost-benefit tradeoffs that likely maintain variation in human prosociality, we hypothesize that individual differences in prosocial personality traits are facultatively calibrated to variation in “embodied capital”—that is, knowledge, skills, or somatic traits that increase expected future fitness. In support of this hypothesis, 2 components of embodied capital—physical strength and formal education—associated positively with Tsimane’ prosocial leadership orientation (PLO), a broad personality dimension representing gregarious cooperation, interpersonal warmth, and pursuit of leadership. Moreover, using pedigrees to compute heritability estimates, strength and education had additive effects on the heritable variance in PLO, which suggests that prosocial traits may be “reactively heritable” by virtue of their calibration to condition-dependent components of embodied capital. Although alternative explanations must be falsified in future research, our findings 1) provide one of the first demonstrations of adaptively patterned personality variation in a small-scale society and 2) illustrate the potential power of an adaptationist approach to elucidate the causal underpinnings of heritable personality variation