The natural convection boundary-layer flow on a solid vertical surface with heat generated within the boundary layer at a rate proportional to (T - T-infinity)(p) (p >= 1) is considered. The surface is held at the ambient temperature T-infinity except near the leading edge where it is held at a temperature above ambient. The behaviour of the flow as it develops from the leading edge is examined and is seen to become independent of the initial heat input; however, it does depend strongly on the exponent p. For 1 <= p <= 2, the local heating eventually dominates at large distances and there is a convective flow driven by this mechanism. For p >= 4, the local heating does not have a significant effect, the fluid temperature remains relatively small throughout and the heat transfer dies out through a wall jet flow. For 2 < p < 4, the local heating has a significant effect at relatively small distances, with a thermal runaway developing at a finite distance along the surface.

Research with adults has shown a preference for average‐weight female figures with waist‐to‐hip ratios (WHR) of 0.7, and average weight male figures with waist‐to‐hip ratios of 0.9. This study investigated the development of preferences for WHR sizes as well as preferences for specific body weights. Five‐hundred eleven children ranging in age from 6 to 17 were presented with drawings of 12 male and 12 female silhouettes varying in weight and WHR and asked to select one they thought looked the nicest or most attractive. The youngest children showed preferences for the underweight figures, changing to consistent preferences for the average weight figures in the teenage years. The developmental curves for waist‐to‐hip ratio preferences were linear, changing gradually over time to become more adult‐like. Potential developmental models for the development of preferences for specific body shapes are considered in relation to these data.

The incidence of anorexia nervosa has increased significantly in the last century, particularly in rich, "Westernized" cultures. Well-documented risk factors include sex, age, social circumstances, and personality. How can a syndrome that reduces fertility-- and sometimes leads to death-- spread so easily? and why is there heritable variance for some of the risk factors? Evolutionary models postulate that anorexia is a set of coordinated responses to stress that, for other mammals and in our own evolutionary past, led to increased survival and reproductive success. According to these models, the "epidemic" of anorexia that we now see is a "modern pathology"-- an adaptation that, due to changes in our environment, has "gone awry" and become maladaptive. Changes in both the nutritional environment and the social environment of Western culture have led to increased triggering of this once-adaptive syndrome, with risk-factors mapping onto social and personality features that would have been relevant in our evolutionary past. In particular, the triggering role of social stressors related to female competition suggests that anorexia may be a symptom of social manipulation, and that the low fertility of anorectics may be the result of an adaptive strategy of more dominant women to decrease the success of their reproductive competitors.

For decades researchers have been examining attitudes, cultural beliefs, and stereotypes of rape known as “rape myths,” yet demand characteristics of laboratory research can affect participant responses. To investigate one relevant situational variable, 83 young adults approached in a public mall were given the Rape Myth Acceptance Scale (RMAS), by one of two female researchers. One researcher dressed conservatively while the other dressed provocatively; half way through the study the researchers switched clothing to counterbalance any other experimenter effects besides that of clothing. A 2 × 2 be-tween-subjects ANOVA found that: (1) as expected, men scored higher than women on the RMAS; (2) surprisingly, both men and women scored higher on the RMAS when the researcher was dressed conservatively than dressed provocatively; (3) this paradoxical effect of researcher's clothing was more pronounced for men's scores than women's. We interpret this experimenter effect in two ways: (1) the respondents may not have wanted to offend the researcher dressed in provocative clothing or (2) respondents felt more free to share their RMA with the researcher who was dressed conservatively. The large effect of a simple situational variable calls into question the generalizability of specific studies of sexual attitudes.

The Perception-Action Model of empathy (PAM) is both sufficiently broad and sufficiently detailed to be able to describe and accommodate a wide range of phenomena – including the apparent “cold-heartedness” or lack of empathy of psychopaths. We show how the physiological, cognitive, and emotional elements of the PAM map onto known and hypothesized attributes of the psychopathic personality.

Patterns of dream content indicating a predominance of themes relating to threat are likely to reflect biases in dream recall and dream scoring techniques. Even if this pattern is not artifactual, it is set reflective of threat-related biases in our conscious crud nonconscious waking cognition, and is not special to dreams.

As disciplines, evolutionary psychology and behavior genetics have independent—and even antagonistic—histories, assumptions, and methodologies. One point of intersection, however, is their mutual investment in, and reliance on, the concept of kinship. I argue that this mutual concern might serve as common ground supporting an interdisciplinary investigation into the developmental and evolutionary causes of individual differences. In particular, I argue that the statistical main effects reported by each discipline are not particularly illuminating, and that what is needed is a combined effort to unravel the nature of nurture—the rules of epigenesis. To this end I outline a research program which would: (a) identify traits for which heritable variations are adaptive, versus traits for which heritable variations are simply “genetic junk;” then (b) determine how both heritable and non-heritable differences map onto life history strategies.

Citizens of 9 different English-speaking countries (N = 619) evaluated the average, or typical, citizen of 5 English-speaking countries (Great Britain, Canada, Nigeria, United States, Australia) on 9 pairs of bipolar adjectives. Participants were drawn from Australia, Botswana, Canada, Kenya, Nigeria, South Africa, the United States, Zambia, and Zimbabwe. There were statistically significant similarities in the rankings of the 5 stimulus countries on 8 of the 9 adjective dimensions and a strong convergence of autostereotypes and heterostereotypes on many traits. The results relate to previous stereotyping research and traditional methods of assessing the accuracy of national stereotypes.

Several theorists have tried to model anorexia on Wasser and Barash’s (1983) “reproductive suppression model” (RSM). According to the RSM, individual females adaptively suppress their reproductive functioning under conditions of social or physiological stress. From this perspective, mild anorexia is viewed as an adaptive response to modern conditions; more severe anorexia is viewed as an adaptation gone awry. Previous models have not, however, examined the full richness of the RSM. Specifically, Wasser and Barash documented not only self-imposed reproductive suppression, but also manipulative reproductive suppression of subordinate females by dominants. I propose that the modern “epidemic” of anorexia is explained neither by adaptive self-suppression nor by environmental mismatch (an adaptation gone awry); I propose that the “epidemic” levels of anorexia seen in modern western society are a direct consequence of intrasexual competition, the scope of which has been enhanced by the power and reach of modern communications media. According to this perspective, anorexia, even in its mild forms, is a manipulative strategy imposed on subordinates by dominants. Anorexia is, in both senses, a “losing” strategy.

This chapter explores the ultimate factors underlying the development of sex differences in evolutionary history. First is an exploration of how and why a system of two sexes originated. Artificial selection is a process where humans purposefully select which objects, processes, or attributes of things survive and get copied. According to Darwin's model, in the absence of human intervention, nature selects which individuals will survive and reproduce, and it is those individuals who will pass on their traits and attributes to the next generation. Forces of nature which result in selection are called selection pressures. These can be categorized into three major types based on their outcome: directional selection, stabilizing selection, and disruptive selection. The chapter also discusses why the existence of two physical sexes virtually ensures the existence of two psychological sexes. It outlines these differences, presents some of the limitations of, and objections to, this evolutionary logic.

Human behavior can be analyzed using game theory models. Complex games may involve different rules for different players and may allow players to change identity (and therefore, rules) according to complex contingencies. From this perspective, mating behaviors can be viewed as strategic “plays” in a complex “mating game,” with players varying tactics in response to changes in the game's payoff matrix.