Search

It has been hypothesized that even ‘perfect’ polygenic scores (PGSs) composed of only causal variants may not be fully portable between different social groups owing to gene-by-environment interactions modifying the expression of relevant variants. The impacts of such interactions involving two forms of social adversity (low socioeconomic status [SES] and discrimination) are examined in relation to the expressivity of a PGS for educational attainment composed of putatively causal variants in a large, representatively sampled and genotyped cohort of US children. A relatively small-magnitude Scarr–Rowe effect is present (SES × PGSEDU predicting General Cognitive Ability [GCA]; sR = .02, 95% CI [.00, .04]), as is a distinct discrimination × PGSEDU interaction predicting GCA (sR = −.02, 95% CI [−.05, 00]). Both are independent of the confounding main effects of 10 ancestral principal components, PGSEDU, SES, discrimination and interactions among these factors. No sex differences were found. These interactions were examined in relation to phenotypic and genotypic data on height, a prospectively more socially neutral trait. They were absent in both cases. The discrimination × PGSEDU interaction is a co-moderator of the differences posited in modern versions of Spearman’s hypothesis (along with shared environmentality), lending support to certain environmental explanations of those differences. Behavior-genetic analysis of self-reported discrimination indicates that it is nonsignificantly heritable (h2 = .027, 95% CI [−.05, .10]), meaning that it is not merely proxying some underlying source of heritable phenotypic variability. This suggests that experiences of discrimination might stem instead from the action of purely social forces.

Adverse Childhood Experiences (ACEs) are situated as the foundation of a six-tier pyramid, above which rests: (1) disrupted neurodevelopment; (2) social, emotional, and cognitive impairment; (3) adoption of health-risk behaviors; (4) disease, disability, and social problems; and (5) early death. ACEs purportedly initiate a causal sequence of negative developmental, behavioral, social, and cognitive outcomes, culminating in heightened mortality risk. Militating against this causal explanation, life history evolution is herein hypothesized to be the true foundation of any such pyramid. Subsuming ACEs within a life history framework has two broad implications: First, to some extent, ACEs are effectively changed from cause to correlate; second ACEs are seen as markers of strategic life history variation, not markers of dysfunction.

A significant open issue in the field of comparative psychology is the apparent inability to reconcile the existence of ‘little g’ (general intelligence) common factor variance among cognitive performance data involving individuals within species, with the existence of higher-level ‘Big G’ factor variance among species-level cognitive aggregates. Here, using a cognitive individual differences dataset of three Lemur species (grey mouse lemur; Microcebus murinus, ruffed lemur, Varecia variegata, and ring-tailed lemur, Lemur catta), we replicate a previously published solution to this problem. This is based on the hypothesis that there does exist g or g-like variance that is predictive of species differences, but that many of the measures employed in cross-species cognition tests impose floor or ceiling effects on one or more of the species being compared. These will obscure the alignment between g and G when individuals of multiple species are compared. An iterative latent variable moderation model is used, whereby sequentially removing subtests based on lowest coefficient of variance (CV) increases the degree to which g-loadings moderate the species differences among the remaining subtest pool. The correlation between moderator effect magnitude and rising CV across twelve iterations (from fourteen to three subtests) ranges from .710 to .854 based on which pairs of species are being compared. This result is consistent with the expectation that across species, g is highly predictive of species differences (and thus, g and G are one and the same), although significant ‘modular’ differences doubtlessly also exist. Predictions stemming from these observations are outlined using simulations. Finally, the implication of these findings for constructing trans-species valid measures of g and ‘IQ’ for use in future research (such as trans-species GWAS) is discussed.

The Scarr–Rowe effect is a gene × environment interaction, which is characterized by a negative association between exposure to low socioeconomic status (SES) environments and the additive heritability of cognitive ability. Utilizing a polygenic score for educational attainment (EA3), it was found that the two-way interaction between EA3 and parental educational attainment (EA; used as a proxy for parental SES) was a significant positive predictor of participants’ composite cognitive ability (IQ) score (β = .018, SE = .008, p = .028) after controlling hierarchically for the direct effects of (population-stratification-controlled) EA3, parental EA, and 20 distinct interaction terms (10 involving the interactions between the principal components [PCs] and EA3, and 10 involving the interaction between the PCs and parental EA). The presence of this interaction is consistent with the Scarr–Rowe effect, as the expressivity of EA3 on cognitive ability increases with increasing parental EA. No statistically significant sex differences in the effect magnitudes were found, although the effect was significantly present in the female but not male sample.

An open question in comparative psychology is whether the source of correlations among different measures of ability (the

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.

After many waves of out-migration from Africa, different human populations evolved within a great diversity of physical and community ecologies. These ambient ecologies should have at least partially determined the selective pressures that shaped the evolution and geographical distribution of human cognitive abilities across different parts of the world. Three different ecological hypotheses have been advanced to explain human global variation in intelligence: (1) cold winters theory (Lynn, 1991), (2) parasite stress theory (Eppig, Fincher, & Thornhill, 2010), and (3) life history theory (Rushton, 1999, 2000). To examine and summarize the relations among these and other ecological parameters, we divided a sample of 98 national polities for which we had sufficient information into zoogeographical regions (Wallace, 1876; Holt et al., 2013). We selected only those regions for this analysis that were still inhabited mostly by the aboriginal populations that were present there prior to the fifteenth century AD. We found that these zoogeographical regions explained 71.4% of the variance among national polities in our best measure of human cognitive ability, and also more concisely encapsulated the preponderance of the more specific information contained within the sampled set of continuous ecological parameters.

By merging analytical approaches from the fields of historiometrics and behavior genetics, a social pedigree-based estimate of the heritability of eminence is generated. Eminent individuals are identified using the Pantheon dataset. A single super-pedigree, comprised of four prominent and interrelated families (including the Wedgwood–Darwin, Arnold–Huxley, Keynes-Baha’u’lláh, and Benn-Rutherford pedigrees) is assembled, containing 30 eminent individuals out of 301 in total. Each eminent individual in the super-pedigree is assigned a relative measure of historical eminence (scaled from 1 to 100) with noneminent individuals assigned a score of 0. Utilizing a Bayesian pedigree-based heritability estimation procedure employing an informed prior, an additive heritability of eminence of .507 (95% CI [.434, .578]) was found. The finding that eminence is additively heritable is consistent with expectations from behavior-genetic studies of factors that are thought to underlie extraordinary accomplishment, which indicate that they are substantially additively heritable. Owing to the limited types of intermarriage present in the data, it was not possible to estimate the impact of nonadditive genetic contributions to heritability. Gene-by-environment interactions could not be estimated in the present analysis either; therefore, the finding that eminence is simply a function of additive genetic and nonshared environmental variance should be interpreted cautiously.

The “erasing race” effect is the reduction of the salience of “race” as an alliance cue when recalling coalition membership, once more accurate information about coalition structure is presented. We conducted a random-effects model meta-analysis of this effect using five United States studies (containing nine independent effect sizes). The effect was found (ρ = 0.137, K = 9, 95% CI = 0.085 to 0.188). However, no decline effect or moderation effects were found (a “decline effect” in this context would be a decrease in the effect size over time). Furthermore, we found little evidence of publication bias. Synthetically correcting the effect size for bias stemming from the use of an older method for calculating error base rates reduced the magnitude of the effect, but the it remained significant. Taken together, these findings indicate that the “erasing race” effect generalizes quite well across experimental contexts and would, therefore, appear to be quite robust. We reinterpret the theoretical basis for these effects in line with Brunswikian evolutionary-developmental theory and present a series of predictions to guide future research in this area.

Various neuroanatomical volume measures (NVMs) are frequently used as proxies for intelligence in comparative studies, such as the size of the brain, neocortex, and hippocampus, either absolute or controlled for other size measures (e.g., body size, or rest of the brain). Mean species NVMs are moderately correlated with aggregate general intelligence (G), however G and NVMs are yet to be compared in their evolutionary patterns (e.g., conservatism and evolutionary rates) and processes (i.e., their fit to diverse models of evolution reflecting selection regimes). Such evolutionary information is valuable for examining convergence in the evolutionary history among traits and is not available from simple correlation coefficients. Considering accumulating evidence that non-volumetric neurological measures may be as important as (or more so than) volumetric measures as substrates of intelligence, and that certain NVMs negatively predict neuronal density, we hypothesized that discrepancies would be found in evolutionary patterns and processes of G compared to NVMs. We collated data from the literature on primate species means for G, the volumes of the brain, neocortex, cerebellum, and hippocampus, and body mass, and employed phylogenetic comparative methods that examine phylogenetic signal (λ, K), evolutionary rates (σ2), and several parameters of evolutionary models (Brownian motion, Early-burst, acceleration, and Ornstein-Uhlenbeck). Evolutionary rates and acceleration trends were up to an order of magnitude higher for G than for most NVMs, and a strong selection optimum toward which clades evolved was found for G, whereas NVMs conformed mostly to Brownian motion. Brain size was the most contrasting NVM compared to intelligence across most phylogenetic indices examined, showing signs of deceleration and extreme conservativeness. Only certain operationalizations of neocortical and hippocampal volume showed convergence with G, albeit still notably weakly. The NVM with results that most strongly approached the patterns identified for G is residual cerebellar size (relative to body size). In comparison to the most commonly used volumetric measures (operationalization of brain and neocortex size), G must be seen as an evolutionarily labile trait under considerable selection pressure, necessitating that the role of the cerebellum be more aptly recognized and that other neurological factors be invoked as potential substrates for its evolutionary trajectory.

We tracked the relative integration and differentiation among life history traits over the period spanning AD 1800–1999 in the Britannic and Gallic biocultural groups. We found that Britannic populations tended toward greater strategic differentiation, while Gallic populations tended toward greater strategic integration. The dynamics of between-group competition between these two erstwhile rival biocultural groups were hypothesized as driving these processes. We constructed a latent factor that specifically sought to measure between-group competition and residualized it for the logarithmic effects of time. We found a significantly asymmetrical impact of between-group competition, where the between-group competition factor appeared to be driving the diachronic integration in Gallic populations but had no significantly corresponding influence on the parallel process of diachronic differentiation in Britannic populations. This suggests that the latter process was attributable to some alternative and unmeasured causes, such as the resource abundance consequent to territorial expansion rather than contraction.

Coronavirus disease 2019 (COVID-19) has harshly impacted Italy since its arrival in February 2020. In particular, provinces in Italy's Central and Northern macroregions have dealt with disproportionately greater case prevalence and mortality rates than those in the South. In this paper, we compare the morbidity and mortality dynamics of 16th and 17th century Plague outbreaks with those of the ongoing COVID-19 pandemic across Italian regions. We also include data on infectious respiratory diseases which are presently endemic to Italy in order to analyze the regional differences between epidemic and endemic disease. A Growth Curve Analysis allowed for the estimation of time-related intercepts and slopes across the 16th and 17th centuries. Those statistical parameters were later incorporated as criterion variables in multiple General Linear Models. These statistical examinations determined that the Northern macroregion had a higher intercept than the Southern macroregion. This indicated that provinces located in Northern Italy had historically experienced higher plague mortalities than Southern polities. The analyses also revealed that this geographical differential in morbidity and mortality persists to this day, as the Northern macroregion has experienced a substantially higher COVID-19 mortality than the Southern macroregion. These results are consistent with previously published analyses. The only other stable and significant predictor of epidemic disease mortality was foreign urban potential, a measure of the degree of interconnectedness between 16th and 17th century Italian cities. Foreign urban potential was negatively associated with plague slope and positively associated with plague intercept, COVID-19 mortality, GDP per capita, and immigration per capita. Its substantial contribution in predicting both past and present outcomes provides a temporal continuity not seen in any other measure tested here. Overall, this study provides compelling evidence that temporally stable geographical factors, impacting both historical and current foreign pathogen spread above and beyond other hypothesized predictors, underlie the disproportionate impact COVID-19 has had throughout Central and Northern Italian provinces.