Genes, Evolution and Intelligence

Towards an Integrated Concept of Personality in Human and Nonhuman Animals

Every individual has an idiosyncratic way of feeling, thinking and behaving, which is relatively stable across time and situations. Usually known as Personality, today this phenomenon is recognized in many species, including arthropods, fish, avian or mammals. From an evolutionary perspective, research has shown that personality differences are manifest in distinctive forms of dealing with selective pressures, with consequences for fitness. Despite these facts, the study of personality in animals other than humans is relatively new. Only two decades ago, consistent behavioral individual differences were considered 'noise' around an optimal strategy for behavioral ecologists. Also, psychologists were not interested in animal personality as a consequence of the fear of anthropomorphization and the erroneous belief that humans are unique in nature. Fortunately, this misconception seems already overcome but there are still conceptual issues preventing a unified concept of personality. Throughout this review, we first explore the etymological origins of personality and other terminological issues. We further revise the historical course of the study of personality in humans and other animals, from the perspectives of Psychology and Behavioral Ecology, on the basis of the most used approach, the trait theory. We present the study of nonhuman primates as a paradigmatic example in between both frameworks. Finally, we discuss about the necessity of a unified science of personality.

Funny Date, Creative Mate? Unpacking the Effect of Humor on Romantic Attraction

Extensive research shows that people are attracted to funny dating partners, with several competing, sometimes conflicting, explanations for why humor is strongly desired in a mate. The present research asks whether humor is interpreted as a reliable, hard-to-fake indicator of some other, valuable trait. Across six experiments, we manipulated humor in a hypothetical date, online dating profile, or video profile and asked which of several traits statistically linked to humor are reliably inferred about funny partners. Humor-specifically partners producing humor-consistently led to higher ratings of partner creative ingenuity. This effect was not moderated by gender, and mediated desirability for different types of partnership. Results further revealed stronger preference for a first-date activity requiring creative ingenuity with a funny versus non-funny partner. Humor may signal that a potential partner is skilled at creative problem-solving, which may be particularly important when considering various forms of partnership.

The Garden of Forking Paths; An Evaluation of Joseph's 'A Reevaluation of the 1990 "Minnesota Study of Twins Reared Apart" IQ Study'

Joseph has written what purports to be a refutation of studies of Twins Reared-Apart (TRAs) with a singular focus on the Minnesota Study of Twins Reared-Apart (MISTRA). I show, in detail, that (a) his criticisms of previous TRA studies depend on sources that were discredited prior to MISTRA, as they all failed the test of replicability, (b) the list of biases he uses to invalidate MISTRA do not support his arguments, (c) the accusations of questionable research practices are unsubstantiated, (d) his claim that MISTRA should be evaluated in the context of psychology's replication crisis is refuted. The TRA studies are constructive replications. Like many other scholars, past and present, he has been misled by the variation introduced by small samples (sampling error) and the distortion created by walking in the garden of forking paths. His endeavor is a concatenation of elision and erroneous statistical/scientific reasoning.

Between-Group Mean Differences in Intelligence in the United States Are >0% Genetically Caused: Five Converging Lines of Evidence

The past 30 years of research in intelligence has produced a wealth of knowledge about the causes and consequences of differences in intelligence between individuals, and today mainstream opinion is that individual differences in intelligence are caused by both genetic and environmental influences. Much more contentious is the discussion over the cause of mean intelligence differences between racial or ethnic groups. In contrast to the general consensus that interindividual differences are both genetic and environmental in origin, some claim that mean intelligence differences between racial groups are completely environmental in origin, whereas others postulate a mix of genetic and environmental causes. In this article I discuss 5 lines of research that provide evidence that mean differences in intelligence between racial and ethnic groups are partially genetic. These lines of evidence are findings in support of Spearman’s hypothesis, consistent results from tests of measurement invariance across American racial groups, the mathematical relationship that exists for between-group and within-group sources of heritability, genomic data derived from genome-wide association studies of intelligence and polygenic scores applied to diverse samples, and admixture studies. I also discuss future potential lines of evidence regarding the causes of average group differences across racial groups. However, the data are not fully conclusive, and the exact degree to which genes influence intergroup mean differences in intelligence is not known. This discussion applies only to native English speakers born in the United States and not necessarily to any other human populations.

Is There a Correlation Between the Number of Brain Cells and IQ?

Our access to a unique material of postmortem brains obtained from decades of data collection enabled a stereological analysis of the neuron numbers and correlation of results with individual premorbid intelligence quotient (IQ) data. In our sample of 50 brains from men, we find that IQ does not correlate with the number of brain cells in the human neocortex and was only weakly correlated to brain weight. Our stereological examination extended to measures of several other parameters that might be of relevance to intelligence, including numbers of cerebral glial cells (astrocytes, oligodendrocytes, and microglia) and the volume of key areas in the gray and white matter and of the cerebral ventricles, also showing near-zero nonsignificant correlations to IQ.

Cognitive Ability in Everyday Life: The Utility of Open-Source Measures

The measurement of individual differences in cognitive ability has a long and important history in psychology, but it has been impeded by the proprietary nature of most assessment measures. With the development of validated open-source measures of ability (collected in the International Cognitive Ability Resource, or ICAR, available at ICAR-project.com ), it is now possible for many researchers to assess ability in large surveys or small, lab-based studies without the expenses associated with proprietary measures. We review the history of ability measurement and discuss how the growing set of items included in ICAR allows ability assessments to be more generally available to all researchers.

Cognitive Training Does Not Enhance General Cognition

Due to potential theoretical and societal implications, cognitive training has been one of the most influential topics in psychology and neuroscience. The assumption behind cognitive training is that one's general cognitive ability can be enhanced by practicing cognitive tasks or intellectually demanding activities. The hundreds of studies published so far have provided mixed findings and systematic reviews have reached inconsistent conclusions. To resolve these discrepancies, we carried out several meta-analytic reviews. The results are highly consistent across all the reviewed domains: minimal effect on domain-general cognitive skills. Crucially, the observed between-study variability is accounted for by design quality and statistical artefacts. The cognitive-training program of research has showed no appreciable benefits, and other more plausible practices to enhance cognitive performance should be pursued.

Polygenic risk for schizophrenia and measured domains of cognition in individuals with psychosis and controls

Psychotic disorders including schizophrenia are commonly accompanied by cognitive deficits. Recent studies have reported negative genetic correlations between schizophrenia and indicators of cognitive ability such as general intelligence and processing speed. Here we compare the effect of polygenetic risk for schizophrenia (PRS_SCZ) on measures that differ in their relationships with psychosis onset: a measure of current cognitive abilities (the Brief Assessment of Cognition in Schizophrenia, BACS) that is greatly reduced in psychotic disorder patients, a measure of premorbid intelligence that is minimally affected by psychosis onset (the Wide-Range Achievement Test, WRAT); and educational attainment (EY), which covaries with both BACS and WRAT. Using genome-wide single nucleotide polymorphism (SNP) data from 314 psychotic and 423 healthy research participants in the Bipolar-Schizophrenia Network for Intermediate Phenotypes (B-SNIP) Consortium, we investigated the association of PRS_SCZ with BACS, WRAT, and EY. Among apparently healthy individuals, greater genetic risk for schizophrenia (PRS_SCZ) was significantly associated with lower BACS scores (r = -0.17, p = 6.6 × 10^-4 at P_T = 1 × 10^-4), but not with WRAT or EY. Among individuals with psychosis, PRS_SCZ did not associate with variations in any of these three phenotypes. We further investigated the association between PRS_SCZ and WRAT in more than 4500 healthy subjects from the Philadelphia Neurodevelopmental Cohort. The association was again null (p > 0.3, N = 4511), suggesting that different cognitive phenotypes vary in their etiologic relationship with schizophrenia.

The role of questioning environment, personality traits, depressive and anxiety symptoms in tinnitus severity perception

Psychological factors have been described as important for tinnitus severity, but attempts to incorporate them in one picture are sparse. This study investigated to what extent traits (personality), states (depressive and anxiety symptoms), sociodemographic factors and questioning environment influence tinnitus severity perception and how they interplay. Data were obtained from 212 subjects in a survey that was undertaken in 2016 at Vilnius University hospital and via internet. Measures included the Tinnitus Handicap Inventory (THI), Visual Analogue Scale (VAS), Hospital Anxiety and Depression Scale (HADS), Big Five Personality Dimensions Scale and sociodemographic questions. A series of stepwise forward and multiple regression analyses were undertaken to discover how factors interconnect. Female gender, age, living in rural area, but not level of education, were found to be associated with THI and HADS. Total HADS score and of both subscales were linked to scores on THI, VAS scales and all personality traits, except agreeableness (and consciousness for anxiety). Anxiety was the most important predictor for tinnitus severity, followed by depressive symptoms. Only neuroticism from personality dimensions was a predictor of THI score, whereas THI scores did not predict scores on neuroticism. All results in scales were higher in the internet group, except agreeableness and neuroticism, while extroversion correlated negatively with THI score only in the hospital group. Tinnitus severity was highly correlated with depressive, anxiety symptoms and neuroticism. Respondents recruited through internet had higher scores on most parameters. Results emphasize the importance of psychological factors in tinnitus management.

Genetic and environmental influences on household financial distress

Heterogeneity of household financial outcomes emerges from various individual and environmental factors, including personality, cognitive ability, and socioeconomic status (SES), among others. Using a genetically informative data set, we decompose the variation in financial management behavior into genetic, shared environmental and non-shared environmental factors. We find that about half of the variation in financial distress is genetically influenced, and personality and cognitive ability are associated with financial distress through genetic and within-family pathways. Moreover, genetic influences of financial distress are highest at the extremes of SES, which in part can be explained by neuroticism and cognitive ability being more important predictors of financial distress at low and high levels of SES, respectively.

The evolution of general intelligence

The presence of general intelligence poses a major evolutionary puzzle, which has led to increased interest in its presence in nonhuman animals. The aim of this review is to critically evaluate this question and to explore the implications for current theories about the evolution of cognition. We first review domain-general and domain-specific accounts of human cognition in order to situate attempts to identify general intelligence in nonhuman animals. Recent studies are consistent with the presence of general intelligence in mammals (rodents and primates). However, the interpretation of a psychometric g factor as general intelligence needs to be validated, in particular in primates, and we propose a range of such tests. We then evaluate the implications of general intelligence in nonhuman animals for current theories about its evolution and find support for the cultural intelligence approach, which stresses the critical importance of social inputs during the ontogenetic construction of survival-relevant skills. The presence of general intelligence in nonhumans implies that modular abilities can arise in two ways, primarily through automatic development with fixed content and secondarily through learning and automatization with more variable content. The currently best-supported model, for humans and nonhuman vertebrates alike, thus construes the mind as a mix of skills based on primary and secondary modules. The relative importance of these two components is expected to vary widely among species, and we formulate tests to quantify their strength.

Human high intelligence is involved in spectral redshift of biophotonic activities in the brain

Human beings hold higher intelligence than other animals on Earth; however, it is still unclear which brain properties might explain the underlying mechanisms. The brain is a major energy-consuming organ compared with other organs. Neural signal communications and information processing in neural circuits play an important role in the realization of various neural functions, whereas improvement in cognitive function is driven by the need for more effective communication that requires less energy. Combining the ultraweak biophoton imaging system (UBIS) with the biophoton spectral analysis device (BSAD), we found that glutamate-induced biophotonic activities and transmission in the brain, which has recently been demonstrated as a novel neural signal communication mechanism, present a spectral redshift from animals (in order of bullfrog, mouse, chicken, pig, and monkey) to humans, even up to a near-infrared wavelength (∼865 nm) in the human brain. This brain property may be a key biophysical basis for explaining high intelligence in humans because biophoton spectral redshift could be a more economical and effective measure of biophotonic signal communications and information processing in the human brain.

Genome-wide association study of cognitive functions and educational attainment in UK Biobank (N=112 151)

People's differences in cognitive functions are partly heritable and are associated with important life outcomes. Previous genome-wide association (GWA) studies of cognitive functions have found evidence for polygenic effects yet, to date, there are few replicated genetic associations. Here we use data from the UK Biobank sample to investigate the genetic contributions to variation in tests of three cognitive functions and in educational attainment. GWA analyses were performed for verbal-numerical reasoning (N=36 035), memory (N=112 067), reaction time (N=111 483) and for the attainment of a college or a university degree (N=111 114). We report genome-wide significant single-nucleotide polymorphism (SNP)-based associations in 20 genomic regions, and significant gene-based findings in 46 regions. These include findings in the ATXN2, CYP2DG, APBA1 and CADM2 genes. We report replication of these hits in published GWA studies of cognitive function, educational attainment and childhood intelligence. There is also replication, in UK Biobank, of SNP hits reported previously in GWA studies of educational attainment and cognitive function. GCTA-GREML analyses, using common SNPs (minor allele frequency>0.01), indicated significant SNP-based heritabilities of 31% (s.e.m.=1.8%) for verbal-numerical reasoning, 5% (s.e.m.=0.6%) for memory, 11% (s.e.m.=0.6%) for reaction time and 21% (s.e.m.=0.6%) for educational attainment. Polygenic score analyses indicate that up to 5% of the variance in cognitive test scores can be predicted in an independent cohort. The genomic regions identified include several novel loci, some of which have been associated with intracranial volume, neurodegeneration, Alzheimer's disease and schizophrenia.

The genesis and correction of unprofessional behavior in surgeons: The role of society, education and genetics

BACKGROUND

Most surgeons are ethical. Increasingly, however, a variety of unprofessional behaviors are surfacing. Awareness of these behaviors and their causation is required to plan their eradication.

OBJECTIVES

To (i) identify the prevalent causes of unprofessional behaviors amongst surgeons; and (ii) suggest corrective interventions.

METHODS

Literature was searched and models constructed to interpret interrelationships between causes.

FINDINGS

Unprofessional behaviors extend beyond those frequently discussed, necessitating the term 'dysprofessionalism'. Causal influences arise from (i) an overpowering society; (ii) limited education and (iii) the underdeveloped state of human nature at birth. Societies corrupt by role-modeling avarice and encouraging industry-despite consequent pollution. Society brooks no interference. Surgeons are loath to oppose, resulting in an unprofessional silence. Surgical education based on best evidence is an indoctrination, with little opportunity to deploy alternatives. Evidence based guidelines increasingly risk errors, as publication fraud increases. Effective interaction with government/legislation is not taught. Human nature and our brain remain arrested in a stage of strongly stabilized evolutionary selection. Humans are born with larval brains requiring intense educational interventions. Genetic modification holds promise as it can circumvent birth in undeveloped states, and facilitate trans-generational transfer of knowledge. CRISPR/Cas-9 techniques make this possible, necessitating ethical discussion-an urgent issue. Reforming society would otherwise be an impossible task as behaviors cannot be taught in classrooms.

CONCLUSION

Instances of dysprofessionalism are unlikely to diminish using current approaches. Discussion of the ethics of genetically modifying embryos is urgently needed, as this could provide a possible shortcut to positive changes in human behavior, but risks unwanted changes and misuse.

What Does the Shipley-2 Measure for Children and Adolescents? Integrated and Conjoint Confirmatory Factor Analysis With the WISC-IV

We used integrated and conjoint confirmatory factor analysis of Shipley-2 and Wechsler Intelligence Scale for Children–Fourth Edition (WISC-IV) data to investigate constructs measured in the Shipley-2 for children and adolescents. We also estimated Shipley-2 composite reliability at the subtest level rather than the item level. The three Shipley-2 subtests for the most part measured what was described in the manual, although Block Patterns measured visual spatial ability in addition to fluid ability and Abstraction was best considered a measure of psychometric g. The g factors derived from the WISC-IV and Shipley-2 were similar but not identical. Internal reliability estimates for Shipley-2 composites that were based on correlations between the subtests were substantially lower than those based on the items. Last, based on WISC-IV derived g factors, 37% to 53% of the variance in Shipley-2 composites was explained by g. Some of the reliable variance in the Shipley-2 composites was due to something specific that the subtests had in common not explained by psychometric g.