How cognitive genetic factors influence fertility outcomes: A mediational SEM analysis

Utilizing a newly released cognitive Polygenic Score (PGS) from Wave IV of Add Health (n = 1,886), structural equation models (SEMs) examining the relationship between PGS and fertility (which is approximately 50% complete in the present sample), employing measures of verbal IQ and educational attainment as potential mediators, were estimated. The results of indirect pathway models revealed that verbal IQ mediates the positive relationship between PGS and educational attainment, and educational attainment in turn mediates the negative relationship between verbal IQ and a latent fertility measure. The direct path from PGS to fertility was non-significant. The model was robust to controlling for age, sex, and race; furthermore, the results of a multigroup SEM revealed no significant differences in the estimated path coeficients across sex. These results indicate that those predisposed towards higher verbal IQ by virtue of higher PGS values are also predisposed towards trading fertility against time spent in education, which contributes to those with higher PGS values producing fewer offspring at this stage in their life course

Sinistrality is associated with (slightly) lower general intelligence: a data synthesis and consideration of secular trend data in handedness

The relationship between the general factor of intelligence (g) and handedness is investigated using a combined sample of 23511 respondents from three large databases: the NLSY’79 (US), NLSY’97 (US) and NCDS (UK). Dextrals – those who use their right hands were found to be 1.22 IQ points higher than sinistrals (left handers) after controling for sex and age and correcting for sources of measurement error. To see if the association between IQ and handedness was strongest on the abilities that were the best measures of g, the method of correlated vectors was used to test for moderation. Across the three studies, g was found to very weakly negatively moderate the association between ability measure and handedness (ρ=-.023, K=3, N=23511), however in the NLSY’79, the coding speed subtest was an outlier in terms of the strength of its association with handedness. Its removal yielded indications of positive moderation in this dataset, which when aggregated boosted the overall vector correlation value to .539 (K=3, N=23511), suggesting that g might be an important moderator of this relationship. Secondary analysis of secular trend data on the changing percentage of sinistrals in Western populations indicates that overall, sinistrality has increased, entailing a g decline of .106 points over 150 years (.006 points per decade). The secular increase in sinistrality is consistent with other data indicating long-term declines in developmental stability and may stem from some combination of increasing mutation load and advancing maternal age in Western populations

Parent-offspring resemblance for educational attainment reduces with increased social class in a global sample: evidence for the compensatory advantage hypothesis

IntroductionThe degree to which (self-reported) social class predicts parent-offspring resemblance for educational attainment (EA) is examined in a globally representative dataset of 69,116 individuals sourced from 56 countries.MethodsA hierarchical general linear model is used to predict participant EA with the two-way interaction between class and parental EA, after controlling for regional effects, the main effects of age, class, parental EA, and interactions among these.ResultsSocial class-by-parental EA interaction negatively predicts participant EA (semipartial r = −0.04, 95% CI = −0.05 to −0.03), meaning that among those who report belonging to a “higher” social class, the degree of parent-offspring resemblance for EA is reduced, contrary to the Scarr-Rowe hypothesis, which holds that genetic influences on cognitive ability and related phenotypes (captured here in part by parent-offspring resemblance) should be greater among those from higher socioeconomic status (SES) backgrounds. These results replicate using a quantile regression model, where it was found that among those with lower social class ordinals, the strength of the parent-participant EA association is significantly stronger relative to those in the highest ordinal. No significant sex differences are present.DiscussionThese findings are consistent with the compensatory advantage hypothesis, which predicts decreased heritability of EA and related phenotypes among affluent families, as increased access to educational resources should enhance opportunities for cognitive growth in a way that compensates for intrinsic disadvantages

Moral foundations tracked over 200 years of lexicographic data, and their predictors

The prediction that reduction of negative selection decreases group-level competitiveness, as reflected in increased individual-focused and diminished group-focused moral foundations, is tested. To measure this hypothesized shift in moral foundations, we conduct a culturomic analysis of the utilization frequencies of items sourced from the moral foundations item pool, tracked among Britannic populations from 1800 to 1999 using Google Ngram Viewer. The resultant higher-order factor, which tracks increasing individualizing values and decreasing binding values, is termed Asabiyyah (capturing social cohesion and collective purpose). Two predictors of this factor are examined: change in the strength of intergroup competition and change in levels of indicators of developmental instability. Both the strength of intergroup competition and levels of developmental instability associate with Asabiyyah. Rising developmental instability mediates the impact of inter-group competition, indicating that reduced between-group competition might have relaxed negative selection against mutations, which might reduce Asabiyyah via their effects on inter-genomic transactions. These results must be interpreted carefully, given the clear real-world evidence that explicit commitment to group-oriented values often features in harmful and maladaptive social and political ideologies of an extreme character

How Universal Is the General Factor of Personality?

In various personality models, such as the Big Five, a consistent higher order general factor of personality (GFP) can be identified. One view in the literature is that the GFP reflects general social effectiveness. Most GFP studies, however, have been conducted in Western, educated, industrialized, and rich democracies (WEIRD). Therefore, to address the question of the universality of the GFP, we test whether the GFP can also be identified in a preliterate indigenous sample of Tsimane by using self-reports, spouse reports, and interviewer ratings. In the Tsimane, a viable GFP could be identified and the intercorrelations between personality traits were significantly stronger than in samples from industrial countries. The GFP correlated with the ratings of social engagement. In addition, self and spouse ratings of the GFP overlapped. Overall, the findings are in line with the notion that the GFP is a human universal and a substantive personality factor reflecting social effectiveness

Secular slowing auditory simple reaction time in Sweden (1959-1985)

There are indications that simple reaction time might have slowed in Western countries, based on both cohort- and multi-study comparisons. A possible limitation of the latter method in particular is measurement error stemming from methods variance, which results from the fact that instruments and experimental conditions change over time and between studies. We therefore set out to measure the simple auditory reaction time (SRT) of 7,081 individuals (2,997 males and 4,084 females) born in Sweden 1959-1985 (subjects were aged between 27 and 54 years at time of measurement). Depending on cut-offs and adjustment for ageing related slowing on SRT, the data suggest that SRT has increased between 3 and 16 ms in the 27 birth years covered in the present sample. The slowing is unlikely to be explained by attrition, as evaluated by comparing the general intelligence × birth-year interactions and standard deviations for both male participants and dropouts, utilizing military conscript cognitive ability data. The present result is consistent with previous studies employing alternative methods, and may result from several synergistic factors, such as possible recent micro-evolutionary trends favouring lower g in Sweden and the effects of industrially produced neurotoxic substances on peripheral nerve conduction velocity

Behavioral genetics

In this introductory chapter, we discuss the nexus between evolutionary theory and behavioral genetics, using it to elucidate the biological origins of human behavior and motivational predispositions. We introduce relevant behavioral genetics methods and evolutionary theoretical background to provide readers with the necessary conceptual tools to deepen their engagement with evolutionary behavioral genetics—as well as to help them take on the challenge of building a scientifically and evolutionarily more consilient account of human behavior. To demonstrate the utility of behavioral genetics in evolutionary behavioral science, our analytical examples range from personality, cognition, and sexual orientation to pair-bonding. We conclude by presenting a few recent landmark studies in behavioral genetics research with a particular focus on two aspects of sexual behavior: assortative mating and same-sex sexual behavior. This chapter considers behavioral genetics methods and their connection with evolutionary science more broadly while providing a succinct overview of recent advances in understanding the evolutionary genetic underpinnings of human sexual behavior, mate choice, and basic motivational processes. It is a sine qua non of scientifically principled evolutionary behavioral scientists to acknowledge the distal evolutionary and proximal genetic processes which, interlinked, underlie the psychobehavioral predispositions that form the variegated fabric of human societies and, more broadly, the diversity of life found in nature. These evolutionary processes operate from distal selection pressures acting on genetic material through hundreds of millions of years of natural selection—and from individual and population differences in genotypes to their manifestations in complex behavioral phenotypes and life outcomes in contemporary humans—which, in turn, enact concomitant selection pressures on the genetic material underlying and arising from them