I want to provide some valuable nuggets of information from science. Warning: This page also contains some merely speculative thoughts about randomly chosen topics. ||| Auf diesem Blog finden sich eine Mischung von Auszügen aus primär naturwissenschaftlichen Texten und spekulative Gedanken (bzw. persönliche Kurznotizen) zu einer Vielzahl von Themen. Die Bezeichnung "Naturwissenschaftsblog" ist zwar gewagt, reicht aber bis in die Gründungszeit dieses Blogs zurück.
There is a lot discussion if pornography addiction is a real addiction or a pseudo-addiction. But there are more interesting questions: (A) does internet-pornography have any influence on the mating patterns of Western societies? ... and if it does: (B) how strong is that influence?
Speculation about the effects of pornography consumption: (o) a weakening of the urge for romantic attachment + a stregthening of the urge for sexual pleasure; (o) a weakening of long-term mating strategies + a strengthening of short-term mating strategies / promiscuous tendencies; etc.
[Mating patterns are of great interest, because from a biological point of view the future of societies is primarily determined by their mating patterns.]
"Reason must approach nature with the view, indeed, of receiving information from it, not, however, in the character of a pupil, who listens to all that his master chooses to tell him, but in that of a judge, who compels the witnesses to reply to those questions which he himself thinks fit to propose."
"Scientific truth is universal, because it is only discovered by the human brain and not made by it, as art is."
"Invention is quite different from discovery. When we say that someone discovered a thing, we mean that it already existed beforehand: it was just not well-known - for example, America before Columbus. But when someone invents a thing - gunpowder, for example - that thing was not known at all before the artist who made it."
Justin R. Garcia, James MacKillop, Edward L. Aller, Ann M. Merriwether, David Sloan Wilson, J. Koji Lum (Nov 2010)
Human sexual behavior is highly variable both within and between populations. While sex-related characteristics and sexual behavior are central to evolutionary theory (sexual selection), little is known about the genetic bases of individual variation in sexual behavior. The variable number tandem repeats (VNTR) polymorphism in exon III of the human dopamine D4 receptor gene (DRD4) has been correlated with an array of behavioral phenotypes and may be predicatively responsible for variation in motivating some sexual behaviors, particularly promiscuity and infidelity.
We administered an anonymous survey on personal history of sexual behavior and intimate relationships to 181 young adults. We also collected buccal wash samples and genotyped the DRD4 VNTR. Here we show that individuals with at least one 7-repeat allele (7R+) report a greater categorical rate of promiscuous sexual behavior (i.e., having ever had a “one-night stand”) and report a more than 50% increase in instances of sexual infidelity.
DRD4 VNTR genotype varies considerably within and among populations and has been subject to relatively recent, local selective pressures. Individual differences in sexual behavior are likely partially mediated by individual genetic variation in genes coding for motivation and reward in the brain. Conceptualizing these findings in terms of r/K selection theory suggests a mechanism for selective pressure for and against the 7R+ genotype that may explain the considerable global allelic variation for this polymorphism.
Comparative studies of social insects and birds show that the evolution of cooperative and eusocial breeding systems has been confined to species where females mate completely or almost exclusively with a single male, indicating that high levels of average kinship between group members are necessary for the evolution of reproductive altruism. In this paper, we show that in mammals, the evolution of cooperative breeding has been restricted to socially monogamous species which currently represent 5 per cent of all mammalian species. Since extra-pair paternity is relatively uncommon in socially monogamous and cooperatively breeding mammals, our analyses support the suggestion that high levels of average kinship between group members have played an important role in the evolution of cooperative breeding in non-human mammals, as well as in birds and insects.
There is a much bigger genetic distance between dogs and humans than between humans and other primates, but humans and dogs are certainly a better match than humans and many primates. Probably genetic distance alone is only a very rough estimate for mental similarity.
Variation in ecological and demographic characteristics may alter the value of extrapair paternity (EPP) for socially monogamous species, thereby leading to variation in mating strategies among conspecific populations. Environmental factors influencing the need for parental care, and demographic factors influencing relatedness of social pairs or availability of unrelated extrapair partners, are both predicted to influence the direct and indirect benefits of EPP in cooperatively breeding birds. We examined genetic mating strategies in 3 long-term study populations of cooperatively breeding Florida scrub-jays (FSJs; Aphelocoma coerulescens) in which the value of EPP—or opportunities for it—was likely to vary: a fragmented site with a high frequency of inbreeding (potentially elevating the value of EPP as a means of increasing offspring heterozygosity); a suburban population with high rates of brood reduction (potentially elevating the value of shared parental investment); and a wildland site with a high frequency of unrelated breeders and opposite-sex auxiliaries (potentially elevating the opportunity for shared within-group parentage). Despite these differences, genetic monogamy dominated at all sites: 100% of the offspring sampled from the suburban site (144 offspring) and fragmented site (258 offspring), and 99.5% of offspring from the wildland site (367 of 369 offspring) were produced monogamously. Rare exceptions in our study populations demonstrate that, even in the FSJ, genetic monogamy is a plastic trait. The near ubiquity of genetic monogamy across 3 ecologically different study sites, however, suggests that this tendency toward monogamy is impervious to the population-level environmental and social variation that we documented.
We adapt the Multidimensional State Boredom Scale (MSBS) to Chinese.
We revise the MSBS by eliminating differentially functioning items.
European Canadians (vs. Chinese) are more likely to experience state boredom.
Results are consistent with theorizing on cultural differences in ideal affect.
The primary goal of the present research was to examine cross-cultural validity of the Multidimensional State Boredom Scale (MSBS) by comparing a European Canadian sample and a Chinese sample. The secondary goal was to explore cross-cultural differences in the actual experience of boredom between European Canadian and Chinese participants when they completed a psychological survey. After establishing cross-cultural validity of the MSBS by eliminating items that functioned differentially across the two cultural groups, we found that European Canadians scored higher on the MSBS than did Chinese. Results are consistent with the literature on cultural differences in ideal affect, such that European North Americans (vs. East Asians) tend to value high-arousal positive affects (e.g., excitement) more, and low-arousal positive affect less (Tsai, Knutson, & Fung, 2006).
Compassion and pride serve contrasting social functions: Compassion motivates care-taking behavior, whereas pride enables the signaling and negotiation of rank within social hierarchies. Across 3 studies, compassion was associated with increased perceived self-other similarity, particularly to weak or vulnerable others. In contrast, pride was associated with an enhanced sense of similarity to strong others, and a decreased sense of similarity to weak others. These findings were obtained using trait measures (Study 1) and experimental inductions (Studies 2 and 3) of compassion and pride, examining the sense of similarity to strong or weak groups (Studies 1 and 2) and unfamiliar individuals (Study 3). The influences of compassion and pride on perceived self-other similarity could not be accounted for by positive mood, nor was this effect constrained by the ingroup status of the target group or individual. Discussion focuses on the contributions these findings make to an understanding of compassion and pride.
(B) try to find out if your thoughts match reality / try to test your thoughts
(A) observe something (or remember an observation)
(B) try to interpret / to understand the observed phenomenon
“Mental laziness” leads to a neglect of step (B). A mental lazy person doesn't think much about the phenomena he/she sees and does not care much if his/her thoughts are closely related to reality or not.
Using educational status in England from 1170 to 2012, we show that the rate of social mobility in any society can be estimated from knowledge of just two facts: the distribution over time of surnames in the society and the distribution of surnames among an elite or underclass. Such surname measures reveal that the typical estimate of parent–child correlations in socioeconomic measures in the range of 0.2–0.6 are misleading about rates of overall social mobility. Measuring education status through Oxbridge attendance suggests a generalized intergenerational correlation in status in the range of 0.70–0.90. Social status is more strongly inherited even than height. This correlation is unchanged over centuries. Social mobility in England in 2012 was little greater than in preindustrial times. Thus there are indications of an underlying social physics surprisingly immune to government intervention.
Do processing speed and short-term storage exhaust the relation between working memory capacity and intelligence? Cai-Ping Dang, Johan Braeken, Roberto Colom, Emilio Ferrer, Chang Liu Personality & Individual Differences (Feb 2015) Highlights
The roles of processing speed (PS) and short-term storage (STM) were analyzed.
PS accounts for the relation between WMC and Fluid intelligence (Gf).
STM and PS exhaust the correlation between WM and crystallized intelligence (Gc).
PS underlies the correlation between WMC and intelligence.
PS’ relevance decreases when cognitive tasks rely on more acquired crystallized knowledge.
The roles of processing speed (PS) and short-term storage (STM) for explaining the relationship between working memory capacity (WMC) and intelligence are analyzed at the latent variable level. 253 Chinese college students completed thirty-two measures from different content domains tapping the cognitive constructs of interest. The key findings showed that (a) PS accounts for the relationship between WMC and fluid intelligence, (b) STM and PS are required for explaining the correlation between crystallized intelligence and WMC. Therefore, this study provides support for the view that PS underlies the correlation between WMC and intelligence, yet with the nuance that its relevance decreases when cognitive tasks rely on crystallized knowledge and skill.
"As a rough guide, teenagers have about 12,000 words and college students 17,000. Older adults have 17,000 to 21,000 words, and a minority have many more. Some conceited person referred to 20,000 words as being “the incoherence boundary”. I eschew such contemptuous judgements."
"intelligence ranges from 0 to 45,000 words (the real upper limit if one avoids technical jargon)" "Knowledge of the 3000 most frequent words in the English language will probably result in your understanding 95% of what is said to you, and knowledge of 5000 “word families” (the main word and its variants, like quick: quickly, quicker, quickest) should mean that you would be able to understand 99.9%. " "much of good thinking depends on a powerful vocabulary."
Immigration, immigration policies and education of immigrants alter competence levels. This study analysed their effects using PISA, TIMSS and PIRLS data (1995 to 2012, N=93 nations) for natives' and immigrants' competences, competence gaps and their population proportions. The mean gap is equivalent to 4.71 IQ points. There are large differences across countries in these gaps ranging from around +12 to −10 IQ points. Migrants' proportions grow roughly 4% per decade. The largest immigrant-based ‘brain gains’ are observed for Arabian oil-based economies, and the largest ‘brain losses’ for Central Europe. Regarding causes of native–immigrant gaps, language problems do not seem to explain them. However, English-speaking countries show an advantage. Acculturation within one generation and intermarriage usually reduce native–immigrant gaps (≅1 IQ point). National educational quality reduces gaps, especially school enrolment at a young age, the use of tests and school autonomy. A one standard deviation increase in school quality represents a closing of around 1 IQ point in the native–immigrant gap. A new Greenwich IQ estimation based on UK natives' cognitive ability mean is recommended. An analysis of the first adult OECD study PIAAC revealed that larger proportions of immigrants among adults reduce average competence levels and positive Flynn effects. The effects on economic development and suggestions for immigration and educational policy are discussed.
Despite significant evidence that opioids are involved in attachment by mediating social reward and motivation, the role of opioids in the formation of adult social attachments has not been explored. We used the socially monogamous prairie vole (Microtus ochrogaster) to explore the role of endogenous opioids in social bonding by examining partner preference formation in female prairie voles. We hypothesized that μ-opioid receptors (MORs) in the striatum have a critical role in partner preference formation. We therefore predicted that peripheral administration of an opioid receptor antagonist would inhibit partner preference formation, and more specifically, that μ-opioid selective receptor blockade within the striatum would inhibit partner preference formation. To test our hypotheses, we first administered the non-selective opioid antagonist naltrexone peripherally to females during an 18-h cohabitation with a male and later tested the female with a partner preference test (PPT). Females showed a dose schedule-dependent decrease in partner preference in the PPT, with females in the continuous dose group displaying stranger preferences. Next, we administered microinjections of the MOR selective antagonist -Phe-Cys-Tyr--Trp-Arg-Thr-Pen-Thr-NH2 (CTAP) into either the nucleus accumbens shell (NAS) or the caudate-putamen (CP) immediately before a 24-h cohabitation with a male, and later tested the female with a PPT. Females receiving CTAP into the CP, but not the NAS, showed no preference in the PPT, indicating an inhibition of partner preference formation. We show here for the first time that MORs modulate partner preference formation in female prairie voles by acting in the CP.
"It seems to me that the doctrine of the laws of thought might be simplified if we were only to set up two, the law of excluded middle and that of sufficient reason. The former thus: >Every predicate can either be affirmed or denied of every subject.< Here it is already contained in the >either, or< that both cannot occur at once, and consequently just what is expressed by the laws of identity and contradiction. Thus these would be added as corollaries of that principle which really says that every two concept-spheres must be thought either as united or as separated, but never as both at once; and therefore, even although words are brought together which express the latter, these words assert a process of thought which can not be carried out. The consciousness of this infeasibility is the feeling of contradiction. The second law of thought, the principle of sufficient reason, would affirm that the above attributing or denying must be determined by some thing different from the judgment itself, which may be a (pure or empirical) perception, or merely another judgment. This other and different thing is then called the ground or reason of the judgment. So far as a judgment satisfies the first law of thought, it is thinkable; so far as it satisfies the second, it is true[.]"
"Mir dünkt, daß man die Lehre von den Denkgesetzen dadurch vereinfachen könnte, daß man deren nur zwei aufstellte, nämlich das vom ausgeschlossenen Dritten und das vom zureichenden Grunde. Ersteres so: »jedem Subjekt ist jegliches Prädikat entweder beizulegen oder abzusprechen.« Hier liegt im Entweder-Oder schon, daß nicht Beides zugleich geschehen darf, folglich eben Das, was die Gesetze der Identität und des Widerspruchs besagen: diese würden also als Korollarien jenes Satzes hinzukommen, welcher eigentlich besagt, daß jegliche zwei Begriffssphären entweder als vereint, oder als getrennt zu denken sind, nie aber als Beides zugleich; mithin daß, wo Worte zusammengefügt sind, welche Letzteres dennoch ausdrücken, diese Worte einen Denkproceß angeben, der unausführbar ist: das Innewerden dieser Unausführbarkeit ist das Gefühl des Widerspruchs. – Das zweite Denkgesetz, der Satz vom Grunde, würde besagen, daß obiges Beilegen oder Absprechen durch etwas vom Urtheil selbst Verschiedenes bestimmt seyn muß, welches eine (reine oder empirische) Anschauung, oder aber bloß ein anderes Urtheil seyn kann: dieses Andere und Verschiedene heißt alsdann der Grund des Urtheils. Sofern ein Urtheil dem ersten Denkgesetze genügt, ist es denkbar; sofern es dem zweiten genügt, ist es wahr[.]"
This chapter explores the interdependency between economic growth and cognitive human capital, which is also described as cognitive skills or intelligence and is measured either as performance in scholastic achievement tests or IQ. It shows that unlike the mere amount of schooling, intelligence has been a robust predictor of economic growth in the recent past. Plausible mediators of the intelligence effect include greater labor productivity, better institutions, more competent management, lower fertility, and wider time horizons.
Based on the observation of secular gains in intelligence that have become known as Flynn effects, a theory of economic growth is developed that is based on the trans-generational reinforcement between rising intelligence and economic, technological and institutional advances. It provides a parsimonious explanation for the sustained nature of economic growth since the Industrial Revolution, and a conceptual framework for more specific theories and hypotheses.
The chapter arrives at projections of economic growth for the first half of the 21st century that are based on the empiric relationship between current prosperity, human capital, and economic growth. Longer-term predictions are based on our knowledge of the conditions that are required for continued Flynn effects, and of genetic limits to human cognitive development. The conclusion is that in most countries of Europe and North America, the limits of cognitive growth are being approached or have been reached already by the younger generation. There are ongoing Flynn effects in developing countries today. These countries are now reducing the cognitive gaps separating them from the developed countries, but most of them are expected to reach their cognitive limits before the end of the 21st century. Long-term developments after the end of the Flynn effect will be driven primarily by demographic trends. Without major changes in demographic behavior, intelligence is predicted to eventually decline slowly, ending economic growth in most parts of the world within the next 3 to 4 generations. [via E. Kirkegaard]
On the whole, ..., g has shown itself to measure a factor both in goodness and in speed of cognitive process. Such "goodness" is here taken as at bottom indicating clearness. The connection between the goodness and the speed is that of being inter-changeable. If the conditions of the case are such as to eliminate the influence of speed, then g measures goodness, and vice versa. When - as is most usual - both influences are in play, then g measures the efficiency compounded of both. In agreement with this complete inter-changeability between goodness and speed of response, neither of them constitutes a group factor or produces specific correlation. The almost unanimous view that some persons are on the whole unable to think quickly and yet are quite able to think clearly would seem to be a most grave error.
Evolutionary explanations regarding the differential preference for particular traits hold that preferences arose due to traits' association with increased potential for reproductive fitness. Assessments of physical attractiveness have been shown to be related to perceived and measured levels of health, an important fitness-related trait. Despite the robust association between physical attractiveness and health observed in the extant literature, a number of theoretical and methodological concerns remain. Specifically, the research in this area possesses a lack of specificity in terms of measures of health, a reliance on artificial social interactions in assessing physical attractiveness, and a relatively infrequent use of non-student samples and leaves unaddressed the confounding effects of raters of attractiveness. Using these concerns as a springboard, the current study employed data from the National Longitudinal Study for Adolescent Health (N ≈ 15,000; aged 25 to 34 years) to assess the relationship between physical attractiveness and various specific and overall measures of health. Logistic and OLS regression models illustrated a robust association between physical attractiveness and various measures of health, controlling for a variety of confounding factors. In sum, the more attractive a respondent was rated, the less likely he or she was to report being diagnosed with a wide range of chronic diseases and neuropsychological disorders. Importantly, this finding was observed for both sexes. These analyses provide further support for physical attractiveness as a phenotypic marker of health. The findings are discussed in reference to evolutionary theory, and the limitations of the study and future research suggestions are also addressed.
The slow and fast life histories of early birds and night owls: Their future- or present-orientation accounts for their sexually monogamous or promiscuous tendencies Davide Ponzi, Andrea Henry, Konrad Kubicki, Nora Nickels, M. Claire Wilson, Dario Maestripieri (Oct 2014) Evolution and Human Behavior
In this study we tested the hypothesis that inter-individual variation in morningness-eveningness (i.e., chronotype) is associated with variation in a composite measure of life history (the mini-K) such that morning-types (i.e., early birds) exhibit traits typically associated with slow life histories while evening-types (i.e., night owls) exhibit traits typically associated with fast life histories. In addition, we tested the hypothesis that time perspective may be one of the psychological mechanisms mediating the relationship between chronotype and socio-sexuality. Study participants were 95 heterosexual young men, most of whom were university students. Chronotype, life-history traits, socio-sexuality, and time perspective were assessed with well-established self-report measures. Variations in chronotype and in life-history traits were significantly associated in the direction predicted by our hypothesis. Consistent with our second hypothesis, time perspective emerged as a significant mediator of the association between chronotype and socio-sexuality so that the future orientation of morning-types was associated with their long-term mating orientation and relatively low sexual experience, while the present orientation of evening-types was associated with their short-term mating orientation and greater sexual experience. Our study provides the first evidence that variation in chronotype may be adaptive and elucidates one of the psychological mechanisms underlying the life history and reproductive strategies of male early birds and night owls.
A: The position of the polar timberline in present-day Europe
B: The position of the timberline at the most severe stage of the Würm Ice Age. (~22,000 years ago) C: The limits of glacial debris deposited during the Würm Ice Age. D: The limits of glacial debris deposited during the Riss and Mindel Ice Age.
According to Christian Lehmann in its origins the main function of singing/music was the emotional bonding (and behavioral synchronization, respectively) of mother and infant, of families, and of groups. Probably aesthetic preferences vary widely across the world. So it sounds unreasonable to suggest that an art (or high culture) could be created that truly bonds whole humanity.
We investigated to what extent the length of people’s gazes during conversations with opposite-sex persons is affected by the physical attractiveness of the partner. Single participants (N = 115) conversed for 5 min with confederates who were rated either as low or high on physical attractiveness. From a mating strategy perspective, we hypothesized that men’s increased dating desire towards highly attractive confederates would lead to longer periods of gazing, whereas women’s gazing would be less influenced by their dating desire towards highly attractive confederates. Results confirmed our hypothesis, with significantly increased gazing for men in the high attractiveness condition but no significant differences in women in the two attractiveness conditions. Contrary to past research findings, there was no significant sex difference in the size of the effect of physical attractiveness on dating desire. The results were discussed in terms of preference for physically attractive partners and communication strategies during courtship.
The Key to Music's Genetics - Why Music is Part of Being Human
Christian Lehmann (Sept 2014 | English Version) >Amazon<
"Christian Lehmann brings his experience as a musicologist, singer and academic to this fascinating journey through the origins of music and its role in human development, culture and society. Few books on music are as rewarding as this one. Technical terms are clearly described in a way that appeals to both the musically well-informed and the musically inexperienced. Well-chosen examples and amusing asides help to make this a highly informative and extremely readable book – a must for anyone interested in the development of music and how integral it is to the human condition."
For 32 months I studied a community in which much of life revolves around a pair of emotions. Two projects resulted. One, presented elsewhere, is an examination of how and why the given culture shapes and exploits these emotions. The second, presented below, is a consideration of the underlying capacities which make such cultural manipulation possible. Like the other authors in this volume, I hold that the experience of emotion is the combined product of cultural and biological factors. However, rather than explore that synergy, in this essay I attempt to employ the former as a lens with which to view the latter. I begin with a description of a Malay emotion which appears synonymous with shame. However, closer inspection reveals that this emotion can be elicited by two fundamentally different sets of conditions. Moreover, it seems that this duality is a pervasive feature of shame-like emotions around the world. If one adopts the position that the capacity to experience a given type of emotion is the product of evolution, then the duality of shame-like emotions is puzzling, for an evolutionary perspective suggests that each emotion ought to address a discrete facet of life. In order to unravel this puzzle, I search for clues regarding the evolutionary history of shame-like emotions and their opposites, pride-like emotions. I explore the display behaviors and cognitive demands associated with each type of emotion, and conclude that two primitive emotions, which I call Protoshame and Protopride, initially developed in order to motivate the quest for social dominance. I speculate that these emotions served as the foundation for more complex emotions which arose when hominids developed the capacity for a model of mind, that is, the ability to understand that other individuals possess minds like one’s own. Such a capacity creates the possibility of a new class of emotions, the second order emotions, which are a reaction to the subjective experiences of other individuals. After examining such first order emotions as pity and envy, I suggest that Protoshame and Protopride were transformed into two second order emotions, Early Shame and Early Pride, which extended dominance-striving motivations into the new social world created by the advent of the model of mind. However, in addition to enhancing competition, the model of the mind also facilitates cooperation. The possibility of significant cooperation resulted in the development of newersions of Shame and Pride which served to motivate conformity rather than rivalry and, in so doing, set the stage for the blossoming of culture as humankind’s primary adaptation.
Error management theory (EMT) proposes that when the costs of different types of errors are asymmetrical in their fitness consequences, natural selection will create biased cognitive mechanisms that maximize the least costly error (Haselton & Buss, 2000; Haselton & Nettle, 2006). Since the time of its initial publication, EMT has produced dozens of new hypotheses and empirical results characterizing human cognition. With a focus on the last decade of research developments, we summarize evidence of error management biases across a variety of social psychological domains, ranging from perceptions of romantic attraction to social prejudices, cooperative behaviors, and the judgment of personality traits. We then cover emerging theoretical developments, such as the role of context in affecting the magnitude of biases predicted by EMT. We conclude by addressing a recent challenge to the theory – the notion that selection should preserve true beliefs, and therefore is expected only to bias behavior, and not underlying beliefs (cognition), in order to manage error costs (McKay & Dennett, 2009; McKay & Efferson, 2010). We discuss several hypotheses about why, in order to manage error costs, selection targets beliefs.
Males traditionally predominate at upper achievement levels. One general view holds that this is due only to various social factors such as the 'glass ceiling' and lack of female role models. Another view holds that it occurs partly because of innate ability differences, with more males being at upper ability levels. In the last few decades, women have become more achievement focused and competitive and have gained many more opportunities to achieve. The present study examined one intellectual domain, international chess, to quantify its gender differences in achievement and to see if these have been diminishing with the societal changes. Chess is a good test domain because it is a meritocracy, it has objective performance measures, and longitudinal data of a whole population are available. Performance ratings overall and in the top 10, 50 and 100 players of each sex show large gender differences and little convergence over the past three decades, although a few females have become high achievers. The distribution of performance ratings on the January 2004 list shows a higher male mean and evidence for more male variation, just as with traits such as height. Career patterns of players first on the list between 1985 and 1989 show that top males and females entered the list at about the same age but females tend to play fewer games and have shorter careers. In this domain at least, the male predominance is large and has remained roughly constant despite societal changes.
Intelligence is a core construct in differential psychology and behavioral genetics, and should be so in cognitive neuroscience. It is one of the best predictors of important life outcomes such as education, occupation, mental and physical health and illness, and mortality. Intelligence is one of the most heritable behavioural traits. Here, we highlight five genetic findings that are special to intelligence differences and that have important implications for its genetic architecture and for gene-hunting expeditions. (i) The heritability of intelligence increases from about 20% in infancy to perhaps 80% in later adulthood. (ii) Intelligence captures genetic effects on diverse cognitive and learning abilities, which correlate phenotypically about 0.30 on average but correlate genetically about 0.60 or higher. (iii) Assortative mating is greater for intelligence (spouse correlations ~0.40) than for other behavioural traits such as personality and psychopathology (~0.10) or physical traits such as height and weight (~0.20). Assortative mating pumps additive genetic variance into the population every generation, contributing to the high narrow heritability (additive genetic variance) of intelligence. (iv) Unlike psychiatric disorders, intelligence is normally distributed with a positive end of exceptional performance that is a model for ‘positive genetics’. (v) Intelligence is associated with education and social class and broadens the causal perspectives on how these three inter-correlated variables contribute to social mobility, and health, illness and mortality differences. These five findings arose primarily from twin studies. They are being confirmed by the first new quantitative genetic technique in a century—Genome-wide Complex Trait Analysis (GCTA)—which estimates genetic influence using genome-wide genotypes in large samples of unrelated individuals. Comparing GCTA results to the results of twin studies reveals important insights into the genetic architecture of intelligence that are relevant to attempts to narrow the ‘missing heritability’ gap.
This study examined sex differences in money beliefs and behaviours. Over 100,000 British participants completed two measures online, one of which assessed ‘‘money pathology’’ (Forman in Mind over money, Doubleday, Toronto, 1987), and the other four ‘‘money types’’, based on the emotional associations of money (Furnham et al. in Personal Individ Differ, 52:707–711, 2012). Nearly all measures showed significant sex differences with medium to large effect sizes, and with females exhibiting more ‘‘money pathology’’ than males. The biggest difference on the money types was on money being associated with generosity (money representing love) where men scored much lower than females, and autonomy (money representing freedom) where men scored higher than women. For men, more than women, money represented Power and Security. Men were more likely to be Hoarders while women did more emotional regulatory purchasing. Implications and limitations of this study are discussed.
We review recent evidence that suggests that hormonal contraceptives may influence the dynamics of sexual relationships and the human pair-bond. Hormonal contraception likely has positive effects on cementing the pair-bond by decoupling sex from conception. However, changes in women’s evolved mate preferences associated with initiation or discontinuation of hormonal contraception may alter attraction to her partner, with potentially negative consequences for relationship satisfaction. We describe the evidence for such changes produced by laboratory studies, including prospective experimental designs, and how the consequences of such changes are being explored beyond the laboratory. In view of the growing prevalence of modern hormonal contraceptive methods across the globe, further study of such effects is urgently required.
Although male height is positively associated with many aspects of mate quality, average height men attain higher reproductive success in US populations. We hypothesize that this is because the advantages associated with taller stature accrue mainly from not being short, rather than from being taller than average. Lower fertility by short men may be a consequence of their and their partner's lower scores on aspects of mate quality. Taller men, although they score higher on mate quality compared to average height men, may have lower fertility because they are more likely to be paired with taller women, who are potentially less fertile.
We analyzed data from The Integrated Health Interview Series (IHIS) of the United States (N = 165,606). Segmented regression was used to examine patterns across the height continuum.
On all aspects of own and partner quality, shorter men scored lower than both average height and taller men. Height more strongly predicted these aspects when moving from short to average height, than when moving from average to taller heights. Women of a given height who scored lower on mate quality also had shorter partners.
Shorter men faced a double disadvantage with respect to both their own mate quality and that of their spouses. Scores of taller men were only marginally higher than those of average height men, suggesting that being tall is less important than not being short. Although effect sizes were small, our results may partly explain why shorter and taller men have lower fertility than those of average stature.
The majority of research examining sex differences in risk-taking behavior focuses on overt physical risk measures in which failed risk attempts may result in serious injury or death. The present research describes sex differences in patterns of risk taking in day-to-day behavior among Dutch cyclists. Through three observational studies we test sex differences in risk taking in situations of financial risk (fines for failing to use bike lights, Study 1), theft risk (bike locking behavior, Study 2) as well as physical risk (risky maneuvers, Study 3). Results corroborate previous findings by showing that across these domains men are more inclined to take risks than women. We discuss how these findings might be used in an applied context.
Bruce J. Ellis, Aurelio J. Figueredo, Barbara H. Brumbach, Gabriel L. Schlomer (2009)
The current paper synthesizes theory and data from the field of life history (LH) evolution to advance a new developmental theory of variation in human LH strategies. The theory posits that clusters of correlated LH traits (e.g., timing of puberty, age at sexual debut and first birth, parental investment strategies) lie on a slow-to-fast continuum; that harshness (externally caused levels of morbidity-mortality) and unpredictability (spatial-temporal variation in harshness) are the most fundamental environmental influences on the evolution and development of LH strategies; and that these influences depend on population densities and related levels of intraspecific competition and resource scarcity, on age schedules of mortality, on the sensitivity of morbidity-mortality to the organism’s resource-allocation decisions, and on the extent to which environmental fluctuations affect individuals versus populations over short versus long timescales. These interrelated factors operate at evolutionary and developmental levels and should be distinguished because they exert distinctive effects on LH traits and are hierarchically operative in terms of primacy of influence. Although converging lines of evidence support core assumptions of the theory, many questions remain unanswered. This review demonstrates the value of applying a multilevel evolutionary-developmental approach to the analysis of a central feature of human phenotypic variation: LH strategy.
Individual differences in the trial-to-trial variability of reaction time (RT), indexed by the standard deviation of the individual's RTs over n trials (RTSD), generally has a larger negative correlation with psychometric g than does the median RT (RTmd) over n trials. Large data sets are brought to bear on the question of whether RTmd and RTSD, which are highly correlated, reflect one and the same source of variance, but with different reliability and validity for predicting g, or represent independent processes. Several lines of evidence consistently lead to the conclusion that RTmd and RTSD, though having a substantial proportion of their variance in common even when measured separately in experimentally independent sets of RT trials, also have significant independent components of variance, each of which is correlated with psychometric g. Hypotheses about the neurophysiological basis of individual differences in the independent components of RTmd and RTSD are discussed.
[It's likely that RTSD reflects "neural noise" and that individual intelligence differences are partly caused by individual differences in "neural noise".]
>The correlation between T levels and spatial ability is not linear. That is, abilities do not simply increase, pari passu, with T levels. Rather, among normal men, those with higher T levels actually perform worse than those with lower levels (see figure 9-6). This fact is consistent with observations of CAH males. CAH males experience higher androgen levels prenatally than healthy males, but their spatial ability is not enhanced. In fact, some studies report that performance is poorer than in unaffected men. Studies in rats also find that excess testosterone during early development diminishes rather than augments masculinization.
Among normal women, whose base level of T is low, those with higher T levels perform better on spatial tasks than those with lower levels (figure 9-6). Again, this is consistent with the findings from CAH girls, in that pre-natal exposure to higher levels of T generally enhances spatial ability. It appears, therefore, that superior spatial ability is associated with an optimal level of T, neither too low nor too high, apparently in the lower range of normal Caucasian males. (We have no equivalent information for non-Caucasians.) Other abilities investigated to date appear not to be strongly associated with T levels. However, recall that male infants who make the least eye contact, and differ most in this trait from female infants, were exposed prenatally to T levels at the low end of the male range. Those exposed to T levels at the high end of the male range were more similar to females in making more eye contact.<
>The social implications of exceptionally high ability and its interaction with the other factors that make for unusual achievements are considerably greater than the personal implications. The quality of a society’s culture is highly determined by the very small fraction of its population that is most exceptionally endowed. The growth of civilization, the development of written language and of mathematics, the great religious and philosophic insights, scientific discoveries, practical inventions, industrial developments, advancements in legal and political systems, and the world’s masterpieces of literature, architecture, music and painting, it seems safe to say, are attributable to a rare small proportion of the human population throughout history who undoubtedly possessed, in addition to other important qualities of talent, energy, and imagination, a high level of the essential mental ability measured by tests of intelligence.<