The allometry of metabolism and stature: Worker fatigue and height in the Tanzanian labor market

If the positive wage–height correlation is at least partially biological in origin, one plausible pathway is the effect of stature on energy expenditure in individuals. If metabolism scales proportionately with stature, then relative to short individuals, taller individuals can produce more energy for a given work task. This also suggests that end-of-the-workday fatigue, or lack of energy, varies inversely with stature. We test this hypothesis with data from the 2004 Tanzanian Household Worker Survey in which workers report the extent of their fatigue at the end-of-the-workday. Ordinal latent variable parameter estimates reveal that relative to short workers, taller workers are less likely to report being tired at the end-of-the-workday. This suggests that the positive wage–height relationship also has a biological foundation whereby the energy requirements and metabolic costs associated with work effort/tasks are inversely related to stature.     

The perceived benefits of height: strength, dominance, social concern, and knowledge among Bolivian native Amazonians

Research in industrial countries suggests that, with no other knowledge about a person, positive traits are attributed to taller people and correspondingly, that taller people have slightly better socioeconomic status (SES). However, research in some non-industrialized contexts has shown no correlation or even negative correlations between height and socioeconomic outcomes. It remains unclear whether positive traits remain attributed to taller people in such contexts. To address this question, here we report the results of a study in a foraging-farming society of native Amazonians in Bolivia (Tsimane')--a group in which we have previously shown little association between height and socioeconomic outcomes. We showed 24 photographs of pairs of Tsimane' women, men, boys, and girls to 40 women and 40 men >16 years of age. We presented four behavioral scenarios to each participant and asked them to point to the person in the photograph with greater strength, dominance, social concern, or knowledge. The pairs in the photographs were of the same sex and age, but one person was shorter. Tsimane' women and men attributed greater strength, dominance, and knowledge to taller girls and boys, but they did not attribute most positive traits to taller adults, except for strength, and more social concern only when women assessed other women in the photographs. These results raise a puzzle: why would Tsimane' attribute positive traits to tall children, but not tall adults? We propose three potential explanations: adults' expectations about the more market integrated society in which their children will grow up, height as a signal of good child health, and children's greater variation in the traits assessed corresponding to maturational stages.     

Adolescent Characteristics by Type of Long-Term Aim in Life

Surveys were administered to adolescents (N = 144) to determine if young people varied based on the type of long-term aims they held. Using cluster analysis, four groups emerged from the data: youth without clear long-term aims, youth with self-oriented long-term aims, youth with other-oriented long-term aims, and youth with both self- and other-oriented long-term aims. The latter two clusters represent potentially purposeful youth and the self-oriented cluster represents youth with meaning in their lives. Therefore, the authors were able to compare potentially purposeful youth to youth with meaning and to youth with neither purpose nor meaning in their lives. Youth with other-oriented long-term aims were more likely to be searching for a purpose, to have identified a purpose, to report higher levels of life satisfaction, and to score higher on openness. Implications for understanding the purpose construct and for fostering purpose among adolescents are addressed.     

Height is associated with more self-serving beliefs about wealth redistribution

People vary widely in their attitudes towards how much their government should redistribute wealth. Evolutionary theory may shed light on why this variation occurs. Numerous studies have established an association between upper body strength and attitudes towards equality and wealth redistribution in males, showing that physically stronger men are more likely to hold self-serving beliefs on these issues. This effect is typically weaker or absent in women. A question that has received little attention is whether there are similar associations between other aspects of formidability and attitudes towards wealth redistribution. One such aspect is height. I tested this prediction using data from the European Social Survey, in a sample of 27031 people from 20 European countries. Results show that taller people are more likely to have self-serving attitudes towards government redistribution of wealth. The result was robust to numerous control variables and alternative model specifications, but the direct effects of height were small. Taller individuals were less supportive of government wealth redistribution overall, but were especially averse if they were also wealthier. Post-hoc analyses suggested that for lower income deciles, the association was reversed. For these people, there was a positive association between height and support for wealth redistribution. However, effects were equally strong in males and females, and so are not fully consistent with current evolutionary psychological theories of resource distribution.     

Height and reproductive success in a cohort of british men

Two recent studies have shown a relationship between male height and number of offspring in contemporary developed-world populations. One of them argues as a result that directional selection for male tallness is both positive and unconstrained. This paper uses data from a large and socially representative national cohort of men who were born in Britain in March 1958. Taller men were less likely to be childless than shorter ones. They did not have a greater mean number of children. If anything, the pattern was the reverse, since men from higher socioeconomic groups tended to be taller and also to have smaller families. However, clear evidence was found that men who were taller than average were more likely to find a long-term partner, and also more likely to have several different long-term partners. This confirms the finding that tall men are considered more attractive and suggests that, in a noncontracepting environment, they would have more children. There is also evidence of stabilizing selection, since extremely tall men had an excess of health problems and an increased likelihood of childlessness. The conclusion is that male tallness has been selected for in recent human evolution but has been constrained by developmental factors and stabilizing selection on the extremely tall. The National Child Development Study is carried out by the researchers of the Centre for Longitudinal Studies, Institute of Education, London. The data are housed at the Data Archive of the University of Essex, from where they were obtained under license for the present study. I am grateful to Paul Preece for his assistance with data processing, and to Benjamin Campbell and two anonymous referees for invaluable advice which has, I hope, improved the quality of this paper. Daniel Nettle is lecturer in biological psychology at the Open University. With a first degree in psychology and a Ph.D. in biological anthropology, his work has been concerned with the application of evolutionary models to such topics as language (e.g., Linguistic Diversity, Oxford University Press, 1999) and individual differences (Strong Imagination, Oxford University Press, 2001).     

Positive Attitudes to Pediatric HIV Testing: Findings from a Nationally Representative Survey from Zimbabwe

Objective

Early HIV testing and diagnosis are paramount for increasing treatment initiation among children, necessary for their survival and improved health. However, uptake of pediatric HIV testing is low in high-prevalence areas. We present data on attitudes towards pediatric testing from a nationally representative survey in Zimbabwe.

Methods

All 18–24 year olds and a proportion of 25–49 year olds living in randomly selected enumeration areas from all ten Zimbabwe provinces were invited to self-complete an anonymous questionnaire on a personal digital assistant, and 16,719 people agreed to participate (75% of eligibles).

Results

Most people think children can benefit from HIV testing (91%), 81% of people who looked after children know how to access testing for their children and 92% would feel happier if their children were tested. Notably, 42% fear that, if tested, children may be discriminated against by some community members and 28% fear their children are HIV positive. People who fear discrimination against children who have tested for HIV are more likely than their counterparts to perceive their community as stigmatizing against HIV positive people (43% vs. 29%). They are also less likely to report positive attitudes to HIV themselves (49% vs. 74%). Only 28% think it is possible for children HIV-infected at birth to live into adolescence without treatment. Approximately 70% of people (irrespective of whether they are themselves parents) think HIV-infected children in their communities can access testing and treatment.

Conclusions

Pediatric HIV testing is the essential gateway to prevention and care services. Our data indicate positive attitudes to testing children, suggesting a conducive environment for increasing uptake of pediatric testing in Zimbabwe. However, there is a need to better understand the barriers to pediatric testing, such as stigma and discrimination, and address the gaps in knowledge regarding HIV/AIDS in children.     

Facebook Use Predicts Declines in Subjective Well-Being in Young Adults

Over 500 million people interact daily with Facebook. Yet, whether Facebook use influences subjective well-being over time is unknown. We addressed this issue using experience-sampling, the most reliable method for measuring in-vivo behavior and psychological experience. We text-messaged people five times per day for two-weeks to examine how Facebook use influences the two components of subjective well-being: how people feel moment-to-moment and how satisfied they are with their lives. Our results indicate that Facebook use predicts negative shifts on both of these variables over time. The more people used Facebook at one time point, the worse they felt the next time we text-messaged them; the more they used Facebook over two-weeks, the more their life satisfaction levels declined over time. Interacting with other people “directly” did not predict these negative outcomes. They were also not moderated by the size of people''s Facebook networks, their perceived supportiveness, motivation for using Facebook, gender, loneliness, self-esteem, or depression. On the surface, Facebook provides an invaluable resource for fulfilling the basic human need for social connection. Rather than enhancing well-being, however, these findings suggest that Facebook may undermine it.     

Are plants really larger in their introduced ranges?

The "rule" that individuals of nonindigenous plant species are larger where they are introduced than where they are native is not borne out in detailed comparisons of European species introduced to California or the Carolinas and species from California and the Carolinas introduced to Europe. On average, individuals of California species are taller in California than in Europe, while individuals of species native to Europe do not differ between Europe and California. Similarly, individuals of species from the Carolinas are, on average, taller in the Carolinas than in Europe, while individuals of European species are the same height in Europe and the Carolinas or, depending on the nature of the statistical analysis, taller in Europe. Results for herbaceous species only are substantially the same. Although there is no general tendency for species to be taller in their introduced ranges, many species are, in fact, taller in some regions where they are introduced than in their native ranges. Absence of natural enemies in the introduced range is one hypothesis for such observations, but other hypotheses are possible, and the specific reasons for height differences must be sought case by case. The absence of a general tendency casts doubt on the biological control strategy of introducing sequences of phytophages, none of which delivers a knockout blow to a weed, with the expectation that each successive phytophage will force the plant to devote more resources to defense and fewer to traits such as increased size that make it more competitive.     

Love, careers, and heights in France, 2001

Short men are less likely to be married or live in a permanent relationship than their taller counterparts. This pattern is not due to their social status. While blue-collar workers are shorter on average than managers, the effects of height on finding a mate are similar in the two social groups. Being tall is also economically advantageous for men. With identical educational attainment levels, tall men have better careers than short men as they are given greater supervisory responsibilities. In making a commitment, some women might take height into account as an anticipated indicator of future resources of the household. Choice of partner is also influenced by social norms--i.e., partners should be physically well-matched--which is more difficult for shorter men.     

The development of face processing skills.

An early orientation to faces is followed by a gradual development of face processing skills. During the course of maturation, children acquire the ability to learn new faces and to deal with facial transformations. Some skills are achieved more quickly than others. Moreover, encoding ability in young children is somewhat different from that shown by older children. The younger groups fail to take advantage of increased inspection time and stimulus characteristics such as facial distinctiveness. They are also more likely to be confused by alterations in background context. Although with familiar faces they reveal very similar identity priming effects to older children and adults, younger children display a relative inefficiency in categorizing faces as being that of a target unless it is noticeably dissimilar. Young children are more likely than older people to prefer positive caricatures of certain faces, which is not consistent with the view that caricature effects are simple reflections of a general expertise with faces.     

Climate‐mediated habitat selection in an arboreal folivore

The decisions that animals must make to achieve a balance between quantity and quality of resources become more difficult when their habitats are patchy and differ greatly in quality across space and time. Koalas are a prime subject to study this problem because they have a specialised diet of eucalypt leaves and need to balance nutrient and water intake against toxins in the leaves, all of which can change with soil type and climate. Koalas are nocturnal and spend most of the day resting and therefore choose trees for reasons other than feeding, particularly for thermoregulation. We GPS‐tracked 40 koalas over 3 yr to determine their shift in tree selection between day and night, and in relation to daily maximum temperature, in a patchy rural landscape in north‐western NSW, Australia. The species, degree of shelter, diameter, height and elevation of each visited tree were recorded. We used generalised linear mixed effects models to compare tree use between day and night and maximum daily temperature. Koalas used more feed‐trees during the night, and more shelter‐trees during the day. They also selected taller trees with more shelter in the day compared with night. As daytime temperatures rose, koalas increasingly selected taller trees at lower elevations. Our results demonstrate that koalas need taller trees, and non‐feed species with shadier/denser foliage, to provide shelter from heat. This highlights the need both for the retention of taller, mature trees, such as remnant paddock trees, and the planting of both food and shelter trees to increase habitat area and connectivity across the landscape for arboreal species. Retaining and planting trees that provide optimum habitat will help arboreal folivores cope with the more frequent droughts and heatwaves expected with climate change.     

Using self‐portrait photographs to understand self‐concepts of Chinese and American university students

This study examines differences between self‐concepts of Chinese and American university students. Both groups used 35mm cameras to show who they are. They wrote statements about the intended meaning of their best photo. The signs of other people, materials, and objects, and cultural ideas in each photograph were analyzed. Contrary to expectations, a higher percentage of Chinese students portrayed themselves as independent, and a higher percentage of Americans were oriented to other people. Consistent with expectations, Americans were more likely to be oriented towards materials and objects. Both groups were equally likely to be oriented towards cultural ideas.     

Optimal photosynthetic characteristics of individual plants in vegetation stands and implications for species coexistence

AIMS: This paper reviews the way optimization theory has been used in canopy models to analyse the adaptive significance of photosynthesis-related plant characteristics and their consequences for the structure and species composition of vegetation stands. SCOPE: In most studies simple optimization has been used with trait values optimal when they lead to maximum whole-stand photosynthesis. This approach is subject to the condition that the optimum for one individual is independent of the characteristics of its neighbours. This seems unlikely in vegetation stands where neighbour plants strongly influence each other's light climate. Not surprisingly, there are consistent deviations between predicted plant traits and real values: plants tend to be taller, distribute nitrogen more evenly among their leaves and produce more leaf area which is projected more horizontally than predicted by models. CONCLUSIONS: By applying game theory to individual plant-based canopy models, other studies have shown that optimal vegetation stands with maximum whole-stand photosynthesis are not evolutionarily stable. They can be successfully invaded by mutants that are taller, project their leaves more horizontally or that produce greater than optimal leaf areas. While these individual-based models can successfully predict the canopy structure of vegetation stands, they are invariably determined at unique optimal trait values. They do not allow for the co-existence of more than one species with different characteristics. Canopy models can contribute to our understanding of species coexistence through (a) simultaneous analysis of the various traits that determine light capture and photosynthesis and the trade-offs between them, and (b) consideration of trade-offs associated with specialization to different positions in the niche space defined by temporal and spatial heterogeneity of resources.     

Increased sensitivity to nitrazepam in old age.

The effects of a single 10 mg oral dose of nitrazepam were compared with those of a placebo in healthy young and old people. Both the young and the elderly slept better on three successive nights after nitrazepam but they felt less awake at 12 and 36 hours (P less than 0-01). Elderly people made significantly more mistakes in a psychomotor test than did the young, despite similar plasma concentrations of nitrazepam and half lives in the two groups. This difference in response to psychomotor testing is probably explained by an increased sensitivity of the ageing brain to the action of nitrazepam.     

Perceived Racial Discrimination in the Workplace and Body Weight among the Unemployed

This study investigates the association between body weight and the likelihood that people perceive that they have been the victims of racial discrimination in the workplace among the unemployed. I find that unemployed obese men and women are 8.4 percentage points and 7.7 percentage points, respectively, more likely to have experienced racial discrimination before becoming unemployed than their non-obese counterparts. For unemployed men, the relationship between body weight and perceived racial discrimination does not seem to be associated with race. For unemployed women, being black and obese significantly increases the likelihood of perceiving racial discrimination.     

Are Dogs Children,Companions, or Just Animals? Understanding Variations in People's Orientations toward Animals

ABSTRACT

This paper examines the variations in dog owners' attitudes toward, treatment of, and interactions with, animals. Based on 28 in-depth interviews with dog owners from a county in the Midwestern United States, I demonstrate that pets are an important part of many people's lives, often providing companionship, entertainment, and meaningful interactions; however, there are notable, distinct variations in how people relate to them. Pet owners typically exhibit one of three orientations toward pets: “dominionistic,” “humanistic,” or “protectionistic.” The dominionistic have relatively low regard for their pets, valuing them primarily for the uses they provide, such as protection. Those employing the humanistic orientation elevate their pets to the status of surrogate humans and value their pets primarily for the affective benefits they enjoy from their close attachments. The protectionistic have high regard for both pets and animals more generally. They view pets as valuable companions and as creatures with their own interests. This typology offers insights for understanding the source and variety of the often ambiguous and contradictory relations between people and pets. I argue that individual characteristics and experiences impact how people understand and relate to animals, in large part, because they represent exposure to different cultural messages. I suggest that these orientations represent three sets of distinct cultural logics, each with distinct histories and contemporary sources.     

Where Are Zoos Going—or Are They Gone?

ABSTRACT

To some, zoos are prisons exploiting animals. In reality zoos range from bad to better. I make this distinction: A bad zoo makes animals work for it; a good zoo works for animals. Good zoos do effective conservation work and continually strive to improve exhibits, relevance to conservation, and inspiring public engagement for wildlife. Many zoos have improved enormously; the better ones being crucial in saving species that would have otherwise gone extinct. Nonetheless, for some people the mere word “zoo” carries impressions of old zoos, bad zoos, circuses, and theme-park shows that many find distasteful. Good zoos know they must innovate forward. As society grows increasingly estranged from nature and continues driving broad declines of wildlife, wild lands, and natural systems, the goal of zoos and every organization concerned with animal welfare should not be to separate humans from other animals, but to entangle all humans in nonhuman lives. Zoos of the next decades must become the first stage in bringing young people into life-long, engaged caring about animals. They could carry on that mission in their communities, in schools, in wild lands, as well as inside their gates. Without a strong public constituency, wild animals will not withstand continued human proliferation. Zoos and aquariums must innovate toward being a crucial force abetting the continued existence of wildness on Earth. Zoos of the future must become uplifting places of respect, rescue, enhancement, conservation, and public engagement.     

Differential parental investment in families with both adopted and genetic children

Stepchildren are abused, neglected and murdered at higher rates than those who live with two genetically related parents. Daly and Wilson used kin selection theory to explain this finding and labeled the phenomenon “discriminative parental solicitude.” I examined discriminative parental solicitude in American households composed of both genetic and unrelated adopted children. In these families, kin selection predicts parents should favor their genetic children over adoptees. Rather than looking at cases of abuse, neglect, homicide and other antisocial behavior, I focused on the positive investments parents made in their children as well as the outcomes of each child. The results show that parents invested more in adopted children than in genetically related ones, especially in educational and personal areas. At the same time, adoptees experienced more negative outcomes. They were more likely to have been arrested, to have been on public assistance and to require treatment for drug, alcohol or mental health issues. They also completed fewer years of schooling and were more likely to divorce. In adoptive families, it appears that “the squeaky wheel gets the grease.” Parents invest more in adoptees not because they favor them, but because they are more likely than genetic children to need the help. I conclude that discriminative parental solicitude differs in adoptive and step households because adoptive families generally result from prolonged parenting effort, not mating effort like stepfamilies.     

Cooperation and contagion in web-based, networked public goods experiments

A longstanding idea in the literature on human cooperation is that cooperation should be reinforced when conditional cooperators are more likely to interact. In the context of social networks, this idea implies that cooperation should fare better in highly clustered networks such as cliques than in networks with low clustering such as random networks. To test this hypothesis, we conducted a series of web-based experiments, in which 24 individuals played a local public goods game arranged on one of five network topologies that varied between disconnected cliques and a random regular graph. In contrast with previous theoretical work, we found that network topology had no significant effect on average contributions. This result implies either that individuals are not conditional cooperators, or else that cooperation does not benefit from positive reinforcement between connected neighbors. We then tested both of these possibilities in two subsequent series of experiments in which artificial seed players were introduced, making either full or zero contributions. First, we found that although players did generally behave like conditional cooperators, they were as likely to decrease their contributions in response to low contributing neighbors as they were to increase their contributions in response to high contributing neighbors. Second, we found that positive effects of cooperation were contagious only to direct neighbors in the network. In total we report on 113 human subjects experiments, highlighting the speed, flexibility, and cost-effectiveness of web-based experiments over those conducted in physical labs.