What Can Cross-Cultural Correlations Teach Us about Human Nature?

Many recent evolutionary psychology and human behavioral ecology studies have tested hypotheses by examining correlations between variables measured at a group level (e.g., state, country, continent). In such analyses, variables collected for each aggregation are often taken to be representative of the individuals present within them, and relationships between such variables are presumed to reflect individual-level processes. There are multiple reasons to exercise caution when doing so, including: (1) the ecological fallacy, whereby relationships observed at the aggregate level do not accurately represent individual-level processes; (2) non-independence of data points, which violates assumptions of the inferential techniques used in null hypothesis testing; and (3) cross-cultural non-equivalence of measurement (differences in construct validity between groups). We provide examples of how each of these gives rise to problems in the context of testing evolutionary hypotheses about human behavior, and we offer some suggestions for future research

Genetic Associations Between Personality Traits and Lifetime Reproductive Success in Humans

Personality has been associated with reproductive success in humans and other animals, suggesting potential evolutionary selection pressures. However, studies to date have only examined these associations on a phenotypic level, which may be inadequate in estimating evolutionary change. Using a large longitudinal twin dataset of contemporary Finns, we compared the phenotypic (breeder’s equation) and genetically informed (the Robertson–Price identity) associations between lifetime reproductive success (LRS) and two personality traits—neuroticism and extraversion. Neuroticism was not associated with LRS at the phenotypic nor genetic level, while extraversion was associated with higher LRS in men both phenotypically and genetically. Compared to the univariate phenotypic analysis, the genetic analysis suggested a larger selection response of extraversion, and a selection response of neuroticism due to indirect selection. We estimated that neuroticism decreases by .05 standard deviations and extraversion increases by .11 standard deviations by one generation. Our results highlight the importance of considering genetic associations between personality and fitness and investigating several inter-related personality traits and their covariance with each other to predict responses to selection more accurately

Review article: MHD wave propagation near coronal null points of magnetic fields

We present a comprehensive review of MHD wave behaviour in the neighbourhood of coronal null points: locations where the magnetic field, and hence the local Alfven speed, is zero. The behaviour of all three MHD wave modes, i.e. the Alfven wave and the fast and slow magnetoacoustic waves, has been investigated in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null points, for a variety of assumptions, configurations and geometries. In general, it is found that the fast magnetoacoustic wave behaviour is dictated by the Alfven-speed profile. In a $\beta=0$ plasma, the fast wave is focused towards the null point by a refraction effect and all the wave energy, and thus current density, accumulates close to the null point. Thus, null points will be locations for preferential heating by fast waves. Independently, the Alfven wave is found to propagate along magnetic fieldlines and is confined to the fieldlines it is generated on. As the wave approaches the null point, it spreads out due to the diverging fieldlines. Eventually, the Alfven wave accumulates along the separatrices (in 2D) or along the spine or fan-plane (in 3D). Hence, Alfven wave energy will be preferentially dissipated at these locations. It is clear that the magnetic field plays a fundamental role in the propagation and properties of MHD waves in the neighbourhood of coronal null points. This topic is a fundamental plasma process and results so far have also lead to critical insights into reconnection, mode-coupling, quasi-periodic pulsations and phase-mixing.Comment: 34 pages, 5 figures, invited review in Space Science Reviews => Note this is a 2011 paper, not a 2010 pape

The Developmental Origins of Health and Disease: Adaptation Reconsidered

It is now well established that an individual’s experience in the womb can have long-term consequences for their health and well-being. From an evolutionary perspective, it can be predicted that organisms will respond to their early conditions adaptively, maximising their prospects for survival and reproductive prospects under the circumstances. However, relatively little attention is given to the fact that there are multiple ways by which such ‘developmental plasticity’ may evolve. It is necessary to consider kinds of plasticity that can involve something other than an individual organism adapting to an external physical environment. Notably, adaptive developmental plasticity occurs between traits within an individual’s body, as well as between individuals (e.g. between mother and foetus). Taking such an inclusive perspective on the nature of developmental plasticity suggests alternative conclusions to the interpretation of patterns of health and disease, and to which kinds of intervention might be expected to be effective

Intergenerational capital flows are central to fitness dynamics and adaptive evolution in humans

Human fitness dynamics are uniquely and profoundly governed by the flow of capital to subsequent generations. Low socioeconomic status individuals may possess limited capacity to direct capital to descendants and may respond to such constraints adaptively or maladaptively. Mitigation of capital constraints may provide practicable routes to alleviation of the behavioural constellation of deprivation

The evolution of predictive adaptive responses in human life history

Item does not contain fulltextMany studies in humans have shown that adverse experience in early life is associated with accelerated reproductive timing, and there is comparative evidence for similar effects in other animals. There are two different classes of adaptive explanation for associations between early-life adversity and accelerated reproduction, both based on the idea of predictive adaptive responses (PARs). According to external PAR hypotheses, early-life adversity provides a ‘weather forecast’ of the environmental conditions into which the individual will mature, and it is adaptive for the individual to develop an appropriate phenotype for this anticipated environment. In internal PAR hypotheses, early-life adversity has a lasting negative impact on the individual's somatic state, such that her health is likely to fail more rapidly as she gets older, and there is an advantage to adjusting her reproductive schedule accordingly. We use a model of fluctuating environments to derive evolveability conditions for acceleration of reproductive timing in response to early-life adversity in a long-lived organism. For acceleration to evolve via the external PAR process, early-life cues must have a high degree of validity and the level of annual autocorrelation in the individual's environment must be almost perfect. For acceleration to evolve via the internal PAR process requires that early-life experience must determine a significant fraction of the variance in survival prospects in adulthood. The two processes are not mutually exclusive, and mechanisms for calibrating reproductive timing on the basis of early experience could evolve through a combination of the predictive value of early-life adversity for the later environment and its negative impact on somatic state.9 p

The Adaptive Basis of Psychosocial Acceleration: Comment on Beyond Mental Health, Life History Strategies Articles [editorial]

Item does not contain fulltextFour of the articles published in this special section of Developmental Psychology build on and refine psychosocial acceleration theory. In this short commentary, we discuss some of the adaptive assumptions of psychosocial acceleration theory that have not received much attention. Psychosocial acceleration theory relies on the behavior of caregivers being a reliable cue of broader ecological conditions and on those ecological conditions being somewhat stable over the individual's lifetime. There is a scope for empirical and theoretical work investigating the range of environments over which these assumptions hold, to understand more deeply why it is that early life family environment exerts such reliable effects on later life-history strategy.4 p

Why are childhood family factors associated with timing of maturation? A role for internal prediction

Children, particularly girls, who experience early familial adversity tend to go on to reach sexual maturity relatively early. This feature of adolescent development is believed to be an evolved strategy that arose because individuals with genes that caused them to mature relatively early under certain conditions left behind more descendants than those who did not. However, although much has been done to uncover the psychological and physiological mechanisms underlying this process, less attention has been paid to the evolutionary reasons behind why it might be advantageous. It has previously been suggested that this strategy evolved because early familial adversity accurately indicated later environmental adversity, under which conditions early reproduction would likely maximize evolutionary fitness. In this article, we contrast this “external prediction” model with an alternative explanation, which builds on the existing explanation and is mutually compatible with it but also distinct from it. We argue that accelerated development is advantageous because early adversity detrimentally affects the individual’s body, increasing later morbidity and mortality; individuals may adapt to this internal setback by accelerating their development. Unlike the external prediction model, this “internal prediction” relies not on temporal environmental continuity but on long-term effects of early circumstances on the body

The influence of early-life nutrition on mortality and reproductive success during a subsequent famine in a pre-industrial population

Individuals with insufficient nutrition during development often experience poorer later-life health and evolutionary fitness. The Predictive Adaptive Response (PAR) hypothesis proposes that poor early-life nutrition induces physiological changes that maximize fitness in similar environments in adulthood and that metabolic diseases result when individuals experiencing poor nutrition during development subsequently encounter good nutrition in adulthood. However, although cohort studies have shown that famine exposure in utero reduces health in favorable later-life conditions, no study on humans has demonstrated the predicted fitness benefit under low later-life nutrition, leaving the evolutionary origins of such plasticity unexplored. Taking advantage of a well-documented famine and unique datasets of individual life histories and crop yields from two preindustrial Finnish populations, we provide a test of key predictions of the PAR hypothesis. Known individuals from fifty cohorts were followed from birth until the famine, where we analyzed their survival and reproductive success in relation to the crop yields around birth. We were also able to test whether the long-term effects of early-life nutrition differed between individuals of varying socioeconomic status. We found that, contrary to predictions of the PAR hypothesis, individuals experiencing low early-life crop yields showed lower survival and fertility during the famine than individuals experiencing high early-life crop yields. These effects were more pronounced among young individuals and those of low socioeconomic status. Our results do not support the hypothesis that PARs should have been favored by natural selection and suggest that alternative models may need to be invoked to explain the epidemiology of metabolic diseases