Biomedical subjects

Daniel Nettle

Publications and source records attributed to Daniel Nettle.

11 recordsLinked to original sources

PubMed2006

Cues of being watched enhance cooperation in a real-world setting.

We examined the effect of an image of a pair of eyes on contributions to an honesty box used to collect money for drinks in a university coffee room. People paid nearly three times as much for their drinks when eyes were displayed rather than a control image. This finding provides the first evidence from a naturalistic setting of the importance of cues of being watched, and hence reputational concerns, on human cooperative behaviour.

Attitude↗

PubMed2006

Schizotypy, creativity and mating success in humans.

There is an evolutionary puzzle surrounding the persistence of schizophrenia, since it is substantially heritable and associated with sharply reduced fitness. However, some of the personality traits which are predictive of schizophrenia are also associated with artistic creativity. Geoffrey Miller has proposed that artistic creativity functions to attract mates. Here, we investigate the relationship between schizotypal personality traits, creative activity, and mating success in a large sample of British poets, visual artists, and other adults. We show that two components of schizotypy are positively correlated with mating success. For one component, this relationship is mediated by creative activity. Results are discussed in terms of the evolution of human creativity and the genesis of schizophrenia.

Adult↗

PubMed2006

The evolution of personality variation in humans and other animals.

A comprehensive evolutionary framework for understanding the maintenance of heritable behavioral variation in humans is yet to be developed. Some evolutionary psychologists have argued that heritable variation will not be found in important, fitness-relevant characteristics because of the winnowing effect of natural selection. This article propounds the opposite view. Heritable variation is ubiquitous in all species, and there are a number of frameworks for understanding its persistence. The author argues that each of the Big Five dimensions of human personality can be seen as the result of a trade-off between different fitness costs and benefits. As there is no unconditionally optimal value of these trade-offs, it is to be expected that genetic diversity will be retained in the population.

Animals↗

PubMed2006

The paranoid optimist: an integrative evolutionary model of cognitive biases.

Human cognition is often biased, from judgments of the time of impact of approaching objects all the way through to estimations of social outcomes in the future. We propose these effects and a host of others may all be understood from an evolutionary psychological perspective. In this article, we elaborate error management theory (EMT; Haselton & Buss, 2000). EMT predicts that if judgments are made under uncertainty, and the costs of false positive and false negative errors have been asymmetric over evolutionary history, selection should have favored a bias toward making the least costly error. This perspective integrates a diverse array of effects under a single explanatory umbrella, and it yields new content-specific predictions.

Animals↗

PubMed2005

A cross-cultural investigation of the role of foot size in physical attractiveness.

Disparate cultural practices suggest that small foot size may contribute to female attractiveness. Two hypotheses potentially explain such a pattern. Sexual dimorphism in foot size may lead observers to view small feet as feminine and large feet as masculine. Alternately, because small female feet index both youth and nulliparity, evolution may have favored a male preference for this attribute in order to maximize returns on male reproductive investment. Whereas the observational hypothesis predicts symmetrical polarizing preferences, with small feet being preferred in women and large feet being preferred in men, the evolutionary hypothesis predicts asymmetrical preferences, with the average phenotype being preferred in men. Using line drawings that varied only in regard to relative foot size, we examined judgments of attractiveness in nine cultures. Small foot size was generally preferred for females, while average foot size was preferred for males. These results provide preliminary support for the hypothesis that humans possess an evolved preference for small feet in females.

Adult↗

PubMed2005

Longitudinal analysis of the effect of prenatal nicotine exposure on subsequent smoking behavior of offspring.

We explored the influence of maternal smoking during pregnancy on the likelihood of smoking among offspring in adolescence and adulthood using data from two similar British birth cohort surveys, the 1958 National Child Development Study and the 1970 British Birth Survey. Similar information was available in each cohort on maternal age at delivery, offspring sex, maternal smoking during pregnancy, parental and offspring socioeconomic status, and parental smoking at the time offspring smoking was assessed at age 16 years. Offspring smoking at 16 years and at 30/33 years were the primary outcomes of interest. Our data support an association between maternal smoking during pregnancy and an increased risk of offspring smoking later in life among female offspring but not among male offspring. Female offspring of mothers who smoked during pregnancy were more likely to smoke at 16 years than were their male counterparts. Moreover, in this same subgroup, female offspring smoking at 16 years was associated with an increased likelihood of smoking at 30/33 years. Further investigation in larger studies with greater detail of factors shaping smoking in childhood and adulthood and biochemically verified outcome measures would be desirable to clarify the relationship.

Adolescent↗

PubMed2004

Evolutionary origins of depression: a review and reformulation.

There has been a recent surge of interest in the evolutionary basis of depression. One approach argues that the affective mechanisms that are dysregulated in depression are adaptations, whilst a second approach argues that depression itself is an adaptation. The evidence relating to whether depression could itself be an adaptation is reviewed. Adaptations generally have four hallmarks; they lack heritable variation, show evidence of good design, are evoked by appropriate triggers, and fitness is reduced where they are absent. Depression shows none of these hallmarks. It is characterized by heritability, recurrence, cognitive impairment, and poor social outcome. In an alternative evolutionary formulation, I argue that evolution has produced a continuous population distribution of affective reactivity that is subject to stabilizing selection. Individuals vulnerable to depression are at the upper end of this distribution. This conceptualization, in which depression itself is not selected for, is compatible with the known clinical and epidemiological facts.

Adaptation, Psychological↗

PubMed2003

Hand laterality and cognitive ability: a multiple regression approach.

Several different associations between hand laterality and cognitive ability have been proposed. Studies reporting different conclusions vary in their procedures for defining laterality, and several of them rely on measures which are statistically problematic. Previous methods for measuring relative hand skill have not satisfactorily separated the overall level of hand skill, which is a known correlate of cognitive ability, from the asymmetry of its distribution. This paper uses a multiple regression paradigm that separates these two components. Support is found for Leask and Crow's [Trends in Cognitive Sciences, 5 (2001) 513] proposal that average cognitive ability increases monotonically with increasing strength of laterality, regardless of its direction. The small average advantage to dextrals stems from them being more strongly lateralised than sinistrals. The paucity of strong dextrals amongst the very gifted is due to a smaller variance in cognitive ability in this group.

Child↗

PubMed2003

Intelligence and class mobility in the British population.

Performance on intelligence tests is known to be associated with class mobility, with high scorers tending to move up the socio-economic hierarchy, and low scorers tending to move down. However, much remains unknown about the association. It is possible that the importance of intelligence varies across different occupational areas, or that there is friction acting against mobility, such that a person from an underprivileged background would have to be more intelligent in order to reach a given position than someone who had had greater social advantage. Data from a longitudinal study of a broad, socially representative cohort of the British population (the NCDS) are used to investigate these questions. The results show that intelligence test scores in childhood are associated with class mobility in adulthood uniformly across all social classes. There is no evidence that those from underprivileged backgrounds have to be disproportionately able in order to reach the professional classes. The study reveals an apparently high level of social mobility and meritocracy in contemporary Britain.

Adolescent↗

PubMed2003

Genetic and linguistic affinities between human populations in Eurasia and West Africa.

This study examines the relationship between genetic distance and linguistic affiliation for five regional sets of populations from Eurasia and West Africa. Human genetic and linguistic diversity have been proposed to be generally correlated, either through a direct link, whereby linguistic and genetic affiliations reflect the same past population processes, or an indirect one, where the evolution of the two types of diversity is independent but conditioned by the same geographical factors. By controlling for proximity, indirect correlations due to common geography are eliminated, and any residual relationships found are likely to reflect common linguistic-genetic processes. Clear relationships between genetic distances and linguistic relatedness are detectable in Europe and East and Central Asia, but not in the Middle East, Southeast Asia, or West Africa. We suggest that linguistic and genetic affiliations will only be correlated under specific conditions, such as where there have been large-scale demic diffusions in the last few thousand years, and relative sedentism in the subsequent period.

Africa, Western↗

PubMed2002

Women's height, reproductive success and the evolution of sexual dimorphism in modern humans.

Recent studies have shown that, in contemporary populations, tall men have greater reproductive success than shorter men. This appears to be due to their greater ability to attract mates. To our knowledge, no comparable results have yet been reported for women. This study used data from Britain's National Child Development Study to examine the life histories of a nationally representative group of women. Height was weakly but significantly related to reproductive success. The relationship was U-shaped, with deficits at the extremes of height. This pattern was largely due to poor health among extremely tall and extremely short women. However, the maximum reproductive success was found below the mean height for women. Thus, selection appears to be sexually disruptive in this population, favouring tall men and short women. Over evolutionary time, such a situation tends to maintain sexual dimorphism. Men do not use stature as a positive mate-choice criterion as women do. It is argued that there is good evolutionary reason for this, because men are orientated towards cues of fertility, and female height, being positively related to age of sexual maturity, is not such a cue.

Adolescent↗