Dienstag, 16. September 2014

Genetics and intelligence differences: five special findings

Genetics and intelligence differences: five special findings
Robert Plomin & Ian J. Deary (2014)


Abstract

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.

Sex Differences in Money Pathology in the General Population

Sex Differences in Money Pathology in the General Population
Adrian Furnham, Sophie von Stumm, Mark Fenton-O’Creevy (2014)


Abstract

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.

ORAL CONTRACEPTION AND ROMANTIC RELATIONSHIPS – FROM THE LAB TO THE REAL WORLD

ORAL CONTRACEPTION AND ROMANTIC  RELATIONSHIPS – FROM THE LAB TO THE REAL  WORLD 
S. Craig Roberts, Kelly D. Cobey, Kateřina Klapilová & Jan Havlíček (2014)


Abstract

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.

Sonntag, 14. September 2014

Non-linear associations between stature and mate choice characteristics for American men and their spouses

Non-linear associations between stature and mate choice characteristics for American men and their spouses
Gert Stulp, Melinda Mills, Thomas V. Pollet and Louise Barrett
American Journal of Human Biology (July/August 2014)


Abstract

Objectives

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.

Methods

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.

Results

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.

Conclusions

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.











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Sex Differences in Risk Taking Behavior among Dutch Cyclists

Sex Differences in Risk Taking Behavior among Dutch Cyclists
Cobey KD, Stulp G, Laan F, Buunk AP, Pollet TV; (2013)
http://www.epjournal.net/wp-content/uploads/EP11350364.pdf


Abstract

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.

Freitag, 5. September 2014

Fundamental Dimensions of Environmental Risk - The Impact of Harsh versus Unpredictable Environments on the Evolution and Development of Life History Strategies

Bruce J. Ellis, Aurelio J. Figueredo, Barbara H. Brumbach, Gabriel L. Schlomer (2009)


Abstract

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.