Genetic similarity theory,intelligence, and human mate choice

When we tested predictions from genetic similarity theory, we found that spouses assort on the basis of the more genetically influenced of cognitive tests. From our analysis of data from several studies employing 15 subtests from the Hawaii Family Study of Cognition and 11 subtests from the Wechsler Adult Intelligence Scale, we calculated positive correlations between assortive mating coefficients and estimates of genetic influence both between and within samples. Thus, estimates of genetic influence calculated on Koreans and Canadians predicted assortive mating in European Americans in Hawaii and California. These observations were weaker when the g loadings of the tests, on which the spouses assorted most, were partialled out. They confirm the robust nature of the phenomenon and suggest the epigenetic rules may incline people to detect and prefer genetically similar others as marriage partners.     

The territorial foundations of human property

Many animal species have morphological and cognitive adaptations for fighting with others to gain resources, but it remains unclear how humans make fighting decisions. Non-human animals adaptively calibrate fighting behavior to ecological variables such as resource quantity and resource distribution. Also, many species reduce fighting costs by resolving disputes based on power asymmetries or conventions. Here we show that humans apply an ownership convention in response to the problem of costly fighting. We designed a virtual environment where participants, acting as avatars, could forage and fight for electronic food items (convertible to cash). In two experimental conditions, resources were distributed uniformly or clustered in patches. In the patchy condition, we observed an ownership convention — the avatar who arrives first is more likely to win — but in the uniform condition, where costly fights are rare, the ownership convention is absent.     

Social intelligence, human intelligence and niche construction

This paper is about the evolution of hominin intelligence. I agree with defenders of the social intelligence hypothesis in thinking that externalist models of hominin intelligence are not plausible: such models cannot explain the unique cognition and cooperation explosion in our lineage, for changes in the external environment (e.g. increasing environmental unpredictability) affect many lineages. Both the social intelligence hypothesis and the social intelligence-ecological complexity hybrid I outline here are niche construction models. Hominin evolution is hominin response to selective environments that earlier hominins have made. In contrast to social intelligence models, I argue that hominins have both created and responded to a unique foraging mode; a mode that is both social in itself and which has further effects on hominin social environments. In contrast to some social intelligence models, on this view, hominin encounters with their ecological environments continue to have profound selective effects. However, though the ecological environment selects, it does not select on its own. Accidents and their consequences, differential success and failure, result from the combination of the ecological environment an agent faces and the social features that enhance some opportunities and suppress others and that exacerbate some dangers and lessen others. Individuals do not face the ecological filters on their environment alone, but with others, and with the technology, information and misinformation that their social world provides.     

Detection of human genetic linkage: foundations

Starting with the basics of inheritance, recombination, and genetic map distance, we develop the theory of linkage analysis considering data on an individual or on a sib pair, with and without data on parents. We discuss the effects of ascertainment of individuals with certain traits and the effects of allelic associations between a trait and a linked marker locus.     

Prospects for the biology of human intelligence

Despite the ubiquitous nature of Spearman's g in mental test performance, the charge «intelligence is what intelligence tests test» has not been countered in a satisfactory way. It is proposed that there are two ways to answer this complaint. The first concerns the new hypothesis testing models in factor analysis. The second involves studying the ‘biology of intelligence’. The biology of intelligence has various meanings and four are discussed: biology as theory; biology as race and genetics; biology as neurobiology; and biology as basic psychological processes. The last of these is considered in some detail and it is found that reaction time, evoked potentials and inspection time offer bright prospects for further research on the biology of psychometric intelligence.     

Pride,personality, and the evolutionary foundations of human social status

Based on evolutionary logic, Henrich and Gil-White [Evolution and Human Behavior, 22(3), 165–196] distinguished between two routes to attaining social status in human societies: dominance, based on intimidation, and prestige, based on the possession of skills or expertise. Independently, emotion researchers Tracy and Robins [Journal of Personality and Social Psychology, 92(3), 506–525] demonstrated two distinct forms of pride: hubristic and authentic. Bridging these two lines of research, this paper examines whether hubristic and authentic pride, respectively, may be part of the affective-motivational suite of psychological adaptations underpinning the status-obtaining strategies of dominance and prestige. Support for this hypothesis emerged from two studies employing self-reports (Study 1), and self-and peer-reports of group members on collegiate athletic teams (Study 2). Results from both studies showed that hubristic pride is associated with dominance, whereas authentic pride is associated with prestige. Moreover, the two facets of pride are part of a larger suite of distinctive psychological traits uniquely associated with dominance or prestige. Specifically, dominance is positively associated with traits such as narcissism, aggression, and disagreeableness, whereas prestige is positively associated with traits such as genuine self-esteem, agreeableness, conscientiousness, achievement, advice-giving, and prosociality. Discussion focuses on the implications of these findings for our understanding of the evolutionary origins of pride and social status, and the interrelations among emotion, personality, and status attainment.     

Genetic studies of human apolipoproteins

Summary Apolipoprotein H (APO H) has recently been identified as a structural component of chylomicrons, very low-density lipoproteins (VLDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL). Although the precise metabolic function of APO H in lipid metabolism is not certain, it has been suggested that APO H may be involved in triglyceride (TG) metabolism. In addition to the previously described quantitative polymorphism, we have recently detected a common qualitative polymorphism at the APO H structural locus. To test the role of APO H genetic variation in determining lipoprotein and lipid levels, we have estimated the allelic effects of APO H variation on TG, VLDL, LDL, HDL, HDL3, and total cholesterol on 356 Nigerian blacks(189 males, 167 females). While no significant effect of phenotype was observed on lipoprotein levels, the effect of interaction between phenotype and gender was significant. Therefore, data on males and females were analyzed separately using analysis of variance after adjusting for age and body mass index. Logarithmic transformation of pertinent variables was done to bring the distribution of the variables closer to normality. A statistically significant effect of phenotype was observed on triglyceride levels in females only (P<0.05). Further analysis of this phenotypic effect revealed that it is due to the impact of the APO H ^* 3 allele, which raises triglycerides by 9.92 mg/dl as compared to the common allele, APO H ^* 2. These findings are in accordance with the postulated role of APO H in triglyceride metabolism. On the basis of its sex-specific effect, we propose a hypothesis that may explain the combined influence of the quantitative and qualitative polymorphisms at the APO H locus on triglyceride levels in females.     

Association of chronotype and social jetlag with human non-verbal intelligence

The aim of this study was to evaluate the effects of chronotype and social jetlag (SJL) on intelligence. Subjects were aged 14–25 years (n = 1008). A significant effect of intelligence on academic performance, as measured by the Raven’s Standard Progressive Matrices test, was found (F_2,917 = 11.75, P < 0.0001, η² = 0.03). When SJL was less than 2 hours, the intelligence of people with late chronotype was found to be higher than that of subjects with early and intermediate chronotypes (F_2,305 = 3.12, P < 0.05, η² = 0.02). A negative effect of SJL on the results of intelligence testing was noted only in subjects with late chronotype (F_2,536 = 2.61, P < 0.05, η² = 0.02). Our data suggest that people with late chronotype have a higher level of intelligence, but these advantages disappear when SJL ≥2 hours.     

Distinct neurocognitive strategies for comprehensions of human and artificial intelligence

Although humans have inevitably interacted with both human and artificial intelligence in real life situations, it is unknown whether the human brain engages homologous neurocognitive strategies to cope with both forms of intelligence. To investigate this, we scanned subjects, using functional MRI, while they inferred the reasoning processes conducted by human agents or by computers. We found that the inference of reasoning processes conducted by human agents but not by computers induced increased activity in the precuneus but decreased activity in the ventral medial prefrontal cortex and enhanced functional connectivity between the two brain areas. The findings provide evidence for distinct neurocognitive strategies of taking others' perspective and inhibiting the process referenced to the self that are specific to the comprehension of human intelligence.     

Cooperation and human cognition: the Vygotskian intelligence hypothesis

Nicholas Humphrey's social intelligence hypothesis proposed that the major engine of primate cognitive evolution was social competition. Lev Vygotsky also emphasized the social dimension of intelligence, but he focused on human primates and cultural things such as collaboration, communication and teaching. A reasonable proposal is that primate cognition in general was driven mainly by social competition, but beyond that the unique aspects of human cognition were driven by, or even constituted by, social cooperation. In the present paper, we provide evidence for this Vygotskian intelligence hypothesis by comparing the social-cognitive skills of great apes with those of young human children in several domains of activity involving cooperation and communication with others. We argue, finally, that regular participation in cooperative, cultural interactions during ontogeny leads children to construct uniquely powerful forms of perspectival cognitive representation.     

Lionel Penrose and the concept of normal variation in human intelligence

Lionel Penrose (1898-1972) was an important leader during the mid-20th century decline of eugenics and the development of modern medical genetics. However, historians have paid little attention to his radical theoretical challenges to mainline eugenic concepts of mental disease. Working from a classification system developed with his colleague, E. O. Lewis, Penrose developed a statistically sophisticated and clinically grounded refutation of the popular position that low intelligence is inherently a disease state. In the early 1930s, Penrose advocated dividing "mental defect" (low intelligence) into two categories: "pathological mental defect," which is a disease state that can be traced to a distinct genetic or environmental cause, and "subcultural mental defect," which is not an inherent disease state, but rather a statistically necessary manifestation of human variation in intelligence. I explore the historical context and theoretical import of this contribution, discussing its rejection of typological thinking and noting that it preceded Theodosius Dobzhansky's better-known defense of human diversity. I illustrate the importance of Penrose's contribution with a discussion of an analogous situation in contemporary medicine, the controversial practice of using human growth hormone injections to treat "idiopathic short stature" (mere diminutive height, with no distinct cause). I show how Penrose's contributions to understanding human variation make such treatments appear quite misguided.     

Genetic analysis of human immunity indices

Familial correlation ratios of immunology parameters were calculated for pairs of "parent-child", "sibs", "parent-parent". It was concluded that some immunity factors were inherited.     

Genetic determination of the human EEG

Summary In this article, we have discussed recent progress in quantifying the genetically determined component of the resting EEG. This progress has been made possible in particular by the application of advanced information processing techniques such as supervised learning, and the development of a problem-oriented similarity concept. Our work aimed at modeling previous findings regarding the distinct individuality of human brain-wave patterns, the high similarity between the EEGs of monozygotic twins, and the average within-pair similarity of dizygotic twins. Thus, we had three objectives: First, we wanted to improve the quantification of EEG characteristics with respect to reproducibility and specificity by means of adaptive procedures and repeated measurements. Second, we wanted to compare the typical within-subject EEG similarity with the typical within-pair EEG similarity of monozygotic and dizygotic twins brought up together. Finally, we were interested in the degree to which environmental factors affect the characteristics of human brain-wave patterns. Our investigations were based on the empirical data derived from five different populations: (1) 81 healthy subjects, (2) 24 pairs of monozygotic twins brought up together, (3) 25 pairs of dizygotic twins brought up together, (4) 28 pairs of monozygotic twins reared apart, and (5) 21 pairs of dizygotic twins reared apart. Following our similarity conception, repeated measurements on the set of 81 individuals were used as design samples, and new registrations from the same individuals taken 14 days later were referred to as test samples in order to develop the appropriate method and to determine all required calibration parameters. This specific approach allowed us to construct EEG spectral patterns which, with a specificity and reproductibility of>90% each, largely met the requirements of genetic EEG studies. Hence, we were able systematically to investigate the within-pair EEG similarity of our twin samples. Our results provided ample evidence that the individual characteristics of the resting EEG are primarily determined by genetic factors: (1) There exists an almost perfect one-to-one mapping between each individual and his EEG; (2) monozygotic twins proved, with respect to their resting EEGs, to be only slightly less like one another (if there is any difference at all) than each person is to himself over time; (3) the average within-pair EEG similarity estimated from a sufficiently representative sample of dizygotic twins is significantly above the inter-individual EEG similarity between unrelated persons (this finding holds true for both samples of dizygotic twins brought up together and reared apart, and there is also no statistically significant difference in the resting EEG between these two samples) and, (4) the EEGs of monozygotic twins reared apart are obviously as similar to each other as are the EEGs of the same person over time, and there is no statistically significant difference in the resting EEG between the two populations of monozygotic twins brought up together and monozygotic zygotic twins reared apart.     

Genetic polymorphism of human plasminogen.

Using isoelectric focusing (IEF) in polyacrylamide gel of neuraminidase-treated serum or plasma samples and immunofixation or caseinolytic overlay after urokinase activation of gels, a common genetic polymorphism in human plasminogen has been delineated. Two alleles PLGN*A and PLGN*B, were observed with gene frequencies in whites of .69 and .30; in Orientals of .96 and .03; and in blacks of .80 and .18. Several rare alleles were also found. The distribution of phenotypes fits the Hardy-Weinberg equilibrium. Inheritance is autosomal codominant and fits the expectations of Mendelian inheritance. There is fetal synthesis, but no transplacental passage of plasminogen in either direction.