Child nutrition in the transition from nomadic pastoralism to settled lifestyles: individual, household, and community-level factors

The research reported here examines child nutrition in a population that is currently experiencing a transition in subsistence, shifting from nomadic pastoralism to a variety of settled lifestyles. We investigate the range of nutritional consequences of settlement both within and between communities by examining individual, household, and community-level predictors of child nutritional status. Data are drawn from the Rendille Demographic and Health Survey, which contains anthropometric data from 1,088 children ages 6 months to 10 years, as well as socioeconomic data from 640 households drawn from one nomadic and four economically and ecologically diverse settled communities. Comparisons allow us to test the widely held assumption that settlement results in nutritional improvements. The examination of individual and household-level factors highlights several important influences on child nutrition. We find a complex interaction between gender and birthorder, whereby firstborn sons have significantly higher weight-for-height scores than other children, potentially reflecting preference under a system of primogeniture. We also find a complex interaction between defacto female-headed households, where males are absent for over half of the year, and economic status. Young children from poor female-headed households have significantly lower weight-for-height than other children, possibly due to the fact that these households are amongst the poorest in the entire community. However, young children from economically sufficient female-headed households actually fare better than their counterparts in male headed households, suggesting that in households with any discretionary resources, female heads prioritize food acquisition relative to other concerns. Finally, our comparison of child nutritional status across communities, while controlling for individual and household-level variation, does not support the contention that settlement is associated with nutritional improvements. Rather, the effect of community, and its associated changes in subsistence and lifestyle, results in either no nutritional changes, or in the case of young children in the lowland desert community of Korr, diminished nutritional status. Our results underscore the importance of considering variation in sample composition and socioeconomic status when performing community comparisons, and highlight the central role of women in influencing the nutritional welfare of their families.     

Multiple testing in candidate gene situations: a comparison of classical, discrete, and resampling-based procedures

In candidate gene association studies, usually several elementary hypotheses are tested simultaneously using one particular set of data. The data normally consist of partly correlated SNP information. Every SNP can be tested for association with the disease, e.g., using the Cochran-Armitage test for trend. To account for the multiplicity of the test situation, different types of multiple testing procedures have been proposed. The question arises whether procedures taking into account the discreteness of the situation show a benefit especially in case of correlated data. We empirically evaluate several different multiple testing procedures via simulation studies using simulated correlated SNP data. We analyze FDR and FWER controlling procedures, special procedures for discrete situations, and the minP-resampling-based procedure. Within the simulation study, we examine a broad range of different gene data scenarios. We show that the main difference in the varying performance of the procedures is due to sample size. In small sample size scenarios,the minP-resampling procedure though controlling the stricter FWER even had more power than the classical FDR controlling procedures. In contrast, FDR controlling procedures led to more rejections in higher sample size scenarios.     

Body composition and nutritional status of urban Guatemalan children of high and low socioeconomic class

The effects of socioeconomic differences on the nutritional status of two groups of urban living children are considered via an anthropometric assessment of body composition. The sample consists of 981 Guatemala City children, 7.00 to 13.99 years old, of high and low socioeconomic status (SES). High SES children have larger median values for triceps skinfold, subscapular skinfold, arm circumference, and estimated mid-arm muscle and fat areas than low SES children. Compared with children of a US reference sample, the high SES children generally have larger values for all variables and the low SES children have smaller values. However, the differences between the low SES children and the children of the other two samples are greater for arm fat area than for arm muscle area. The analysis suggests that low SES Guatemalan children suffer to a greater extent from chronic energy, rather than protein, undernutrition. A similar pattern of energy malnutrition has been observed for rural Guatemalan children. These combined data suggest that estimates of fat reserves of the arm provide a useful indication of nutritional status for Third-World children. Results from rural Costa Rican and Honduran studies have been taken to mean that muscle reserves are better than fat reserves as indicators of nutritional status in developing countries. But, those studies did not estimate cross-sectional muscle and fat areas and only considered the extremes of the population distribution for muscle and fat.     

Do diet and taxonomy influence insect gut bacterial communities?

Many insects contain diverse gut microbial communities. While several studies have focused on a single or small group of species, comparative studies of phylogenetically diverse hosts can illuminate general patterns of host–microbiota associations. In this study, we tested the hypotheses that (i) host diet and (ii) host taxonomy structure intestinal bacterial community composition among insects. We used published 16S rRNA gene sequence data for 58 insect species in addition to four beetle species sampled from the Sevilleta National Wildlife Refuge to test these hypotheses. Overall, gut bacterial species richness in these insects was low. Decaying wood xylophagous insects harboured the richest bacterial gut flora (102.8 species level operational taxonomic units (OTUs)/sample ± 71.7, 11.8 ± 5.9 phylogenetic diversity (PD)/sample), while bees and wasps harboured the least rich bacterial communities (11.0 species level OTUs/sample ± 5.4, 2.6 ± 0.8 PD/sample). We found evidence to support our hypotheses that host diet and taxonomy structure insect gut bacterial communities (P < 0.001 for both). However, while host taxonomy was important in hymenopteran and termite gut community structure, diet was an important community structuring factor particularly for insect hosts that ingest lignocellulose‐derived substances. Our analysis provides a baseline comparison of insect gut bacterial communities from which to test further hypotheses concerning proximate and ultimate causes of these associations.     

Effect of renutrition on the proliferation kinetics of PHA stimulated lymphocytes from malnourished children

The fraction of lymphocytes that responded to phytohemagglutinin (PHA) stimulation and initiated cellular proliferation (stimulation index or SI) was determined in groups of healthy and severely malnourished children. SI was determined again in the latter group after a period of nutritional recovery. The proportion of interphasic cells showing PHA response was assessed adding bromodeoxyuridine to the culture, so proliferative nuclei appear big and stain light blue, with dispersed granular chromatin and apparent nucleoli, while non-proliferative nuclei look small, stain red, and have compact and homogeneous chromatin. In mitotic nuclei, differential staining of sister chromatids made it possible to distinguish cells that had gone through one, two and three or more proliferation cycles. Based on the data obtained from interphase nuclei and mitosis, the SI was estimated 48 and 72 h of culture. SI were higher in lymphocytes from healthy children than in those from children with severe malnutrition, even after the period of nutritional recovery. However, the SI was significantly higher in lymphocytes from malnourished children after nutritional recovery. Although in these children more cells are stimulated, there seems to be still damage that causes a cycling delay.     

Are there differences in body dimensions among children from matings at different exogamic levels?

The aim of this study was to investigate if there are differences in body dimensions among children from matings of different levels of exogamy. The cross-sectional sample consisted of 285 children, 136 males and 149 females, 6 to 10 years old, attending elementary schools in Tortoli, a town in east-central Sardinia. The children were divided into four groups according to the level of exogamy. One of them included the children of parents born in the same Sardinian village is highly endogamous. For each sex, the Kruskal-Wallis test revealed no significant differences among the four groups of children for the 35 anthropometric variables considered, with the exception of head circumference in the male sample. In particular, there were no significant differences among the four groups of children for some anthropometric variables that are considered to be indirect indicators of nutritional status: sum of skinfolds, waist/hip ratio, body mass index, total upper arm area, upper arm muscle area, upper arm fat area. We conclude that Sardinian children from marriages of different levels of exogamy do not differ in body dimensions if they have similar nutritional conditions.     

28S rDNA evolution in the Eumalacostraca and the phylogenetic position of krill

The Malacostraca are an ancient and morphologically diverse class of Crustacea. The phylogenetic position of one order within this class, the Euphausiacea ("krill," subclass Eumalacostraca) was investigated using 28S rDNA sequences from representatives of several malacostracan orders. Phylogenies for these sequences were estimated by maximum-likelihood and maximum-parsimony analysis. The results of these analyses produced a new scheme for evolution within the Eumalacostraca. The new phylogenies suggested that Euphausiacea are most closely related to the Mysida and not the Decapoda, as is generally thought. Furthermore, the Mysida were found not to be closely related to the Lophogastrida, which are often considered their sister taxon. These hypotheses were tested against the hypotheses of monophyly for the Eucarida, Mysidacea, and Peracarida and found to be significantly better on the basis of the 28S rDNA data.     

Sex differences in spatial cognition in an invertebrate: the cuttlefish

Evidence of sex differences in spatial cognition have been reported in a wide range of vertebrate species. Several evolutionary hypotheses have been proposed to explain these differences. The one best supported is the range size hypothesis that links spatial ability to range size. Our study aimed to determine whether male cuttlefish (Sepia officinalis; cephalopod mollusc) range over a larger area than females and whether this difference is associated with a cognitive dimorphism in orientation abilities. First, we assessed the distance travelled by sexually immature and mature cuttlefish of both sexes when placed in an open field (test 1). Second, cuttlefish were trained to solve a spatial task in a T-maze, and the spatial strategy preferentially used (right/left turn or visual cues) was determined (test 2). Our results showed that sexually mature males travelled a longer distance in test 1, and were more likely to use visual cues to orient in test 2, compared with the other three groups. This paper demonstrates for the first time a cognitive dimorphism between sexes in an invertebrate. The data conform to the predictions of the range size hypothesis. Comparative studies with other invertebrate species might lead to a better understanding of the evolution of cognitive dimorphism.     

The decision to feed by a scavenger in relation to the risks of predation and starvation

Recent theoretical models have considered how nutritional status and predation risk affect the decision by an individual to forage. We consider the feeding behaviour of a scavenger under risk of predation. The intertidal gastropod Nassarius dorsatus Röding was used to test the following hypotheses: (1) a damaged conspecific should be a less preferred meal than a damaged predator or another species; (2) a scavenger should be able to discriminate between a damaged conspecific in the presence and one in the absence of its predator, preferring the latter; and (3) the decision by a scavenger to feed should reflect a trade-off between nutritional status and the above preferences. Results from the laboratory and field were consistent with predictions. Two hypotheses are suggested from the work: scavengers may generally be less willing to feed on carcases of conspecifics than on those of other species, and intertidal scavengers may commonly face a relative or absolute shortage of food.     

Genome-wide quantitative trait locus association scan of general cognitive ability using pooled DNA and 500K single nucleotide polymorphism microarrays

General cognitive ability ( g ), which refers to what cognitive abilities have in common, is an important target for molecular genetic research because multivariate quantitative genetic analyses have shown that the same set of genes affects diverse cognitive abilities as well as learning disabilities. In this first autosomal genome-wide association scan of g , we used a two-stage quantitative trait locus (QTL) design with pooled DNA to screen more than 500 000 single nucleotide polymorphisms (SNPs) on microarrays, selecting from a sample of 7000 7-year-old children. In stage 1, we screened for allele frequency differences between groups pooled for low and high g . In stage 2, 47 SNPs nominated in stage 1 were tested by individually genotyping an independent sample of 3195 individuals, representative of the entire distribution of g scores in the full 7000 7-year-old children. Six SNPs yielded significant associations across the normal distribution of g , although only one SNP remained significant after a false discovery rate of 0.05 was imposed. However, none of these SNPs accounted for more than 0.4% of the variance of g , despite 95% power to detect associations of that size. It is likely that QTL effect sizes, even for highly heritable traits such as cognitive abilities and disabilities, are much smaller than previously assumed. Nonetheless, an aggregated 'SNP set' of the six SNPs correlated 0.11 ( P  < 0.00000003) with g . This shows that future SNP sets that will incorporate many more SNPs could be useful for predicting genetic risk and for investigating functional systems of effects from genes to brain to behavior.     

Does vestibular stimulation activate thalamocortical mechanisms that reintegrate impaired cortical regions?

Caloric stimulation induced a transient reversal of multimodal hemispatial cognitive deficits in an 81-year-old woman with an acute left cerebral hemisphere stroke. The patient had unawareness of her right hand (asomatognosia), right-sided visual unawareness (hemineglect), aphasia and right-sided weakness (hemiplegia) prior to the stimulation. Transient improvements in impaired sensory, motor, linguistic and cognitive function developed within 30 s following application of the caloric stimulus and onset of horizontal nystagmus. The effect persisted for 3 min and ceased completely after 5 min. While several recent reports have described the capacity of caloric stimulation to transiently improve or reverse a wide range of attentional, cognitive and motor impairments, most examples are in right-hemisphere-damaged patients with long-standing brain injury. Typically, patients have been tested several months or years after the onset of the deficit. A possible mechanism for the temporary reintegration of multiple cognitive functions in this patient is discussed.     

Deficits in Cognitive Control,Timing and Reward Sensitivity Appear to be Dissociable in ADHD

Recent neurobiological models of ADHD suggest that deficits in different neurobiological pathways may independently lead to symptoms of this disorder. At least three independent pathways may be involved: a dorsal frontostriatal pathway involved in cognitive control, a ventral frontostriatal pathway involved in reward processing and a frontocerebellar pathway related to temporal processing. Importantly, we and others have suggested that disruptions in these three pathways should lead to separable deficits at the cognitive level. Furthermore, if these truly represent separate biological pathways to ADHD, these cognitive deficits should segregate between individuals with ADHD. The present study tests these hypotheses in a sample of children, adolescents and young adults with ADHD and controls. 149 Subjects participated in a short computerized battery assessing cognitive control, timing and reward sensitivity. We used Principal Component Analysis to find independent components underlying the variance in the data. The segregation of deficits between individuals was tested using Loglinear Analysis. We found four components, three of which were predicted by the model: Cognitive control, reward sensitivity and timing. Furthermore, 80% of subjects with ADHD that had a deficit were deficient on only one component. Loglinear Analysis statistically confirmed the independent segregation of deficits between individuals. We therefore conclude that cognitive control, timing and reward sensitivity were separable at a cognitive level and that deficits on these components segregated between individuals with ADHD. These results support a neurobiological framework of separate biological pathways to ADHD with separable cognitive deficits.     

Sexual dimorphism in chin shape: implications for adaptive hypotheses

The chin, or mentum osseum, is one of the most distinctive anatomical traits of modern humans. A variety of hypotheses for the adaptive value of the chin have been proposed, ranging from mechanical stress resistance to sexual selection via mate choice. While the sexual selection hypothesis predicts dimorphism in chin shape, most biomechanical hypotheses preclude it. Therefore determining the presence or absence of significant sexual dimorphism in chin shape provides a useful method for differentiating between various adaptive hypotheses; however, this has yet to be done due to a lack of quantitative data on chin shape. The goals of this study are therefore: (1) to introduce a new method for quantifying chin shape and (2) to determine the presence or absence of sexual dimorphism in chin shape in a diverse sample of modern humans. Samples were drawn from recent human skeletal collections representing nine geographic regions. Outlines of mentum osseum contours were quantified using elliptical Fourier function analysis (EFFA). Fourier coefficients were analyzed using principal components analysis (PCA). Sexual dimorphism in chin shape was assessed using PC loadings in the pooled geographic sample, and statistically significant differences were found. These findings provide the first quantitative, morphologically based evidence in support of adaptive hypotheses that predict dimorphism in chin shape, including the sexual selection hypothesis.     

PHYLOGENETIC ANALYSIS OF THE MARINE AND FRESHWATER THALAS-SIOSIROID DIATOMS

The thalassiosiroid centric diatoms are distinguished by at least one synapomorphy, the strutted process or fultoportula. Variously classified as a family (Thalassiosiraceae) or an order (Thalassiosirales) among centric diatoms, it is generally conceded that the group of several hundred fossil and living species is monophyletic as a whole. There are two ecological groups of thalassiosiroids, marine and freshwater. It has been hypothesized, based on an ecletic, non-rigorous, evolutionary taxonomy perspective that both the marine and freshwater ecological groups are also monophyletic, but this hypothesis has never been tested in a rigorous framework. Likewise, the freshwater thalassiosiroid species have been grouped into several genera and subgenera using an evolutionary taxonomic approach, but these hypotheses have not fully been tested using cladistic analysis. Focusing mainly on freshwater species, but including at least one representative of each marine genus and one representative from each of several proposed subgeneric groupings of the genus Thalassiosira , we scored morphological characters for fossil and living marine and freshwater Thalassiosiraceae to test these hypotheses. Our cladistic results provide strong support for monophyly for the freshwater group, but it seems unlikely that the marine group is monophyletic. The cladistic results are corroborated to greater or lesser degrees by the fossil record. The implications for evolution in the group and for taxon sampling in molecular studies we are conducting will be discussed.     

Going round in circles: shape effects in the Ebbinghaus illusion

The Ebbinghaus illusion has traditionally been considered as either a sensory or a cognitive illusion, or some combination of these two. Cognitive contrast explanations take support from the way the illusion varies with the degree of shape similarity between the test and inducing elements; we show, however, that contour interaction explanations may account for this result too. We therefore tested these alternative theories by measuring the illusion with different test shapes as well as different inducer shapes, in all combinations. We found that for angular or hexagonal test shapes there is no similarity effect, and for some shape combinations there is no significant illusion, in contradiction to both of the traditional hypotheses. Instead, we suggest that an integrated model of visual processing is needed to account for the illusion.     

Stunting,Poor Iron Status and Parasite Infection Are Significant Risk Factors for Lower Cognitive Performance in Cambodian School-Aged Children

Background

Nutrition is one of many factors affecting the cognitive development of children. In Cambodia, 55% of children <5 y were anemic and 40% stunted in 2010. Currently, no data exists on the nutritional status of Cambodian school-aged children, or on how malnutrition potentially affects their cognitive development.

Objective

To assess the anthropometric and micronutrient status (iron, vitamin A, zinc, iodine) of Cambodian schoolchildren and their associations with cognitive performance.

Methods

School children aged 6–16 y (n = 2443) from 20 primary schools in Cambodia were recruited. Anthropometry, hemoglobin, serum ferritin, transferrin receptors, retinol-binding protein and zinc concentrations, inflammation status, urinary iodine concentration and parasite infection were measured. Socio-economic data were collected in a sub-group of children (n = 616). Cognitive performance was assessed using Raven’s Colored Progressive Matrices (RCPM) and block design and picture completion, two standardized tests from the Wechsler Intelligence Scale for Children (WISC-III).

Results

The prevalence of anemia, iron, zinc, iodine and vitamin A deficiency were 15.7%; 51.2%, 92.8%, 17.3% and 0.7% respectively. The prevalence of stunting was 40.0%, including 10.9% of severe stunting. Stunted children scored significantly lower than non-stunted children on all tests. In RCPM test, boys with iron-deficiency anemia had lower scores than boys with normal iron status (−1.46, p<0.05). In picture completion test, children with normal iron status tended to score higher than iron-deficient children with anemia (−0.81; p = 0.067) or without anemia (−0.49; p = 0.064). Parasite infection was associated with an increase in risk of scoring below the median value in block design test (OR = 1.62; p<0.05), and with lower scores in other tests, for girls only (both p<0.05).

Conclusion

Poor cognitive performance of Cambodian school-children was multifactorial and significantly associated with long-term (stunting) and current nutritional status indicators (iron status), as well as parasite infection. A life-cycle approach with programs to improve nutrition in early life and at school-age could contribute to optimal cognitive performance.     

Coevolution in an Amazonian hummingbird-plant community

Relationships between hummingbirds and their food plants are often considered to have arisen through coevolution. However, while it is certainly the case that hummingbirds and plants are coevolved, it is not always clear to what extent coevolution has shaped community structure and the morphology of the birds and plants. Here I examine the hummingbird-plant community of a lowland Amazonian rainforest in southeastern Colombia and test hypotheses concerning coevolution and community structure. To determine the strength of interrelationships and the degree to which character displacement has occurred, the distributions of three floral traits (flowering phenology, nectar production and corolla length) and two hummingbird traits (culmen length and foraging ecology) have been statistically tested against random null models. Although the hummingbird-plant community at Matamatá is diverse and is highly likely to have a long shared evolutionary history, there is little evidence for pairwise coevolution. Instead, the community appears to have evolved through diffuse coevolution, resulting in guilds of hummingbirds and plants.     

Cognitive impairment and mortality in a cohort of elderly people.

OBJECTIVES--To investigate the relation between cognitive function and cause specific mortality in people aged 65 and over. DESIGN-A 20 year follow up study of a cohort of randomly selected elderly people living in the community who in 1973-4 had taken part in a nutritional survey funded by the Department of Health and Social Security. SETTING--Eight areas in Britain (five in England, two in Scotland, and one in Wales). SUBJECTS--921 men and women whose cognitive function was assessed by a geriatrician in 1973-4 and for whom data on health, socioeconomic circumstances, and diet had been recorded. RESULTS--Cognitive impairment was associated with increased mortality, in particular death from ischaemic stroke. Those who scored 7 or less on the Hodkinson mental test had a relative risk of dying from stroke of 2.8 (95% confidence interval 1.4 to 5.5), compared with those who gained the maximum score (10), after adjustment for age, sex, blood pressure, serum cholesterol concentration, and vitamin C intake. These associations were independent of illness or social class. At the time of the nutritional survey, cognitive function was poorest in those with the lowest vitamin C status, whether measured by dietary intake or plasma ascorbic acid concentration. The relation between vitamin C status and cognitive function was independent of age, illness, social class, or other dietary variables. CONCLUSION--The relation between cognitive function and risk of death from stroke suggests that cerebrovascular disease is an important cause of declining cognitive function. Vitamin C status may be a determinant of cognitive function in elderly people through its effect on atherogenesis. A high vitamin C intake may protect against both cognitive impairment and cerebrovascular disease.     

A history of plant virology. Cross protection

Cross protection is a type of induced resistance developing in plants against viruses. Its basis is that prior infection with one virus affords protection against closely related ones. Its history started about seventy years ago, when the Dutchman Thung and the Englishman Salaman described the phenomenon independently. During the 1930s, several virologists confirmed the discovery, which was considered the first possibility to protect plants against virus infection. Growing interest also led plant virologists to formulate the first hypotheses on its mechanism, with the onset of a still unsolved debate. The hypotheses, that have been succeeded until the 1970s, included (i) antibody formation, (ii) exhaustion of essential metabolites, (iii) limited sites for virus multiplication, and (iv) specific adsorption by new cell compounds. These hypotheses were re-proposed and discussed on several occasions without arriving at a final conclusion. The statement of molecular genetics of viruses produced new interesting "theories", fundamentally based on the interference between virus strains. A model developed by the Americans Palukaitis and Zaitlin in 1984 indicates that excess of progeny positive-sense RNA of the protecting strain would sequester the minus-strand RNA of the challenging strain. Other models involve a function of the coat protein, or gene recombination. However, no model that could unify all the various facets of cross protection has hitherto been proposed. All that has not stopped the phenomenon having practical application. From the first attempts against a severe disease of cocoa in West Africa realized by Posnette in the 1940s, a number of crops (such as tomato, tobacco, citrus, cucurbits, grapevine, soybean, papaya, and so on) have been submitted to this practice. During the 1980s, cross protection came to a standstill because of the development of new resistant or tolerant cultivars. Its story is by no means ended, and much work is needed to understand its limits and possibilities.     

Inference on Multiple Endpoints in Clinical Trials with Adaptive Interim Analyses

Planned interim analyses which permit early stopping or sample size adaption of a trial are desirable for ethical and scientific reasons. Multiple test procedures allow inference about several hypotheses within a single clinical trial. In this paper, a method which combines multiple testing with adaptive interim analyses whilst controlling the experimentwise error rate is proposed. The general closed testing principle, the situation of a priori ordered hypotheses, and application of the Bonferroni-Holm method are considered. The practical application of the method is demonstrated by an example.