Growth and malnutrition of rural Zimbabwean children (6-17 years of age)

The rural environment is an important factor in delayed growth in developing countries. The aim of this study was to investigate the effects of poor rural living conditions on the growth of a Shona sample in Zimbabwe. In total, 982 subjects aged 6-17 years were analyzed. Mean values of height, weight, skinfolds (triceps, subscapular, suprailiac, biceps, medial calf), cormic index, body mass index (BMI), arm composition (total upper arm area, upper arm muscle area, arm fat area, and arm fat index), fat percentage (%F), centripetal fat ratio (CFR), and the contribution of each skinfold to the adiposity of the trunk and upper limbs are presented. Weight, height, BMI, cormic index, SSCP, TRCP, arm circumference, and arm composition are compared with NHANES percentiles. Boys and girls showed stunting and underweight at ages 11-15 and 8-15, respectively; boys presented particularly severe malnutrition and their means of height and weight were below the 10th percentile. The means of arm circumference, UMA, UFA, and TRCP were below the 15th percentile in both sexes. The contribution of the skinfolds generally showed an overall prevalence of TRCP in both sexes; the contribution of SSCP was prevalent only for the 16- to 17-year-old boys. Males presented a higher CFR than girls after 14 years while females showed an irregular pattern. There was a high incidence of brachycormia and mesocormia in females and males, respectively. Height, weight, and BMI were similar to the values observed in other sub-Saharan countries, although body size was slightly larger than in South Africa and smaller than in Tanzania. The results provide a useful database for future comparisons.     

Age at menarche in urban Argentinian girls: association with biological and socioeconomic factors

Age at menarche is regarded as a sensitive indicator of physical, biological, and psychosocial environment. The aim of this study was to determine the age at menarche and its association with biological and socioeconomic factors in girls from Santa Rosa (La Pampa, Argentina). An observational cross-sectional study was carried out on 1,221 schoolgirls aged 9-15 years. Menarche data were obtained by the status-quo method. Height, sitting height, weight, arm circumference, tricipital and subscapular skinfolds were measured. We also calculated body mass index, measures of body composition and proportions, and fat distribution. To assess socioeconomic factors, parents completed a self-administered questionnaire about their occupation and education, family size, household, and other family characteristics. The median age at menarche - estimated by the logit method--was 12.84 years (95% CI: 12.71, 12.97). Compared with their premenarcheal age peers, postmenarcheal girls had greater anthropometric dimensions through age 12. After this age, only height was higher in the latter group. Data were processed by fitting two logistic regressions, both including age. The first model included anthropometric variables and birth weight, while the second model included the socioeconomic variables. The significant variables derived from each model were incorporated into a new regression: height, sitting height ratio (first model), and maternal education (second model). These three variables remained significantly associated with menarche. The results suggest a relationship between linear growth and menarche and agree with those found in other populations where the advancement of menarche is associated with improved living conditions. In relatively uniform urban contexts, maternal education may be a good proxy for the standard of living.     

Body height in relation to rural-urban migration in Poland

A survey was conducted among 2800 students studying in Wroc?aw, Poland. The questionnaire included questions on the body height of the students and their parents, and place of residence and migration patterns of the students themselves, their parents and their grandparents. Body height in both students and their parents was positively correlated with the size of their place of residence. This was particularly true for male students and their fathers. Body height in students and parents from mobile families was not significantly different from that of their peers from non-mobile families. Body height in mobile individuals was generally between that of non-mobile individuals from rural areas and that of non-mobile individuals from large urban centres. Students from families that had migrated from smaller urban centres to larger ones were taller than students from families that had migrated from rural areas to urban centres. Body height in students was also correlated with the kind of migration that took place. In the students' mothers, body height was higher if the maternal grandparents moved from smaller urban centres to larger urban centres than if the maternal grandparents moved from rural areas to urban centres. In female students, body height depended on whether their mothers had migrated from smaller places of residence to larger places of residence, but was not affected by the degree of migration. Intra-generational migration during the generation of the students' grandparents was associated with increased body height in the students' mothers. On the other hand, intergenerational migration during the generations of the students' grandparents and parents was associated with increased body height in the students' fathers and in female students. Body height was not a reliable indicator of whether an individual migrated from rural areas to Wroc?aw. Far more reliable indicators were the size of the place the student lived their whole life and whether the family had lived in an urban environment for at least two generations.     

Systemic changes in body structure of 17–18-year-old schoolboys

The purpose of this study was to assess the systemic structural changes in the body build of 17-18-year-old schoolboys in the final years of Tartu secondary schools within a height-weight classification dividing anthropometric variables into 5 SD-classes. Weight and height, 9 length, 8 breadth and 2 depth measurements, 16 circumferences and 12 skinfolds were measured. From these 5 length measurements and 53 indices were computed, which characterise the ratios of various parts of the body to body height, to upper and lower limbs' length and body composition. The subjects (n = 253) were divided into five standard deviation classes according to height and weight (Kaarma 1981, 1995). In the first three classes height and weight were proportional: (1) small height--small weight, (2) medium height--medium weight and (3) big height--big weight. In the fourth and the fifth class height and weight were non-proportional. In the fourth class weight was preponderant over height, and in the fifth class height was preponderant over weight. It was proved that a statistical difference exists between the opposite classes--the fourth and the fifth class. It was also revealed that the three proportional classes differ from each other significantly. Increase in body height and weight leads also to an increase in length, breadth and depth measurements, bone thicknesses, circumferences and skinfolds. Rohrer index, body mass index, total percentage of fat by Siri, absolute and relative mass of fat tissue increased from the small to the large class. The relationship of the length, width, and depth measurements, circumferences and bone thicknesses to height remains almost unchanged throughout the proportional classes. These investigations support the position that the whole body model may be reconstructed from body height and weight.     

A Comparative Study on Nutritional Status and Body Composition of Urban and Rural Schoolchildren from Brandsen District (Argentina)

The purpose of this study was to analyze whether nutritional status and body composition varies according to the environment of residence (urban or rural) of children in the Brandsen district (Argentina). Weight, height, arm circumference and tricipital and subscapular skinfolds were performed in 1368 schoolchildren aged 3 to 14. NHANES III reference was used to estimate nutritional status -underweight, stunting, wasting, overweight, and obesity- and to evaluate body composition -deficit and excess of adipose (DA, EA) and muscular (DM, EM) tissues of the arm-. Central fat distribution (CFD) was estimated using the subscapular-tricipital index. A structured questionnaire was implemented to evaluate socio-environmental characteristics. Nutritional categories based on body size and body composition were compared between urban and rural areas of residence using Chi-squared tests (χ2). The results indicated for the total sample: 1.1% underweight, 6.9% stunting, 0.4% wasting, 12.1% overweight, 9.7% obesity, 22.0% DM, 2.5% EM, 0.1% DA, 17.6% EA, and 8.5% CFD. Significant differences between urban and rural areas were found only for CFD. The socio-environmental analysis showed that while access to public services and housing quality was significantly better in the urban area, a considerable number of city households lived under deficient conditions, lacked health insurance and had low socioeconomic level. Fifty-three percent of the undernourished children had DM without urban-rural significant differences, and none of them showed DA. In the overweight plus obesity group, 62.8% presented EA, 6.4% EM, 4.7% DM, and 22.8% CFD. The highest percentages of DM and CFD were recorded in rural areas (p = 0.00). We conclude that the child population shows the “double burden” of malnutrition. The environment of residence does not promote any differentiation in the nutritional status. Nevertheless, the increment of central adiposity and, in some cases of muscle deficit in rural children, suggests a consumption of unbalanced diet.     

Age trends in anthropometric characteristics among 6-9 years old Bengalee Hindu school girls of Kolkata, India

A cross-sectional study of 431 6-9 years old urban Bengalee Hindu schoolgirls of Kolkata, India, was undertaken to study age trends in anthropometric characteristics including regional and subcutaneous adiposity. The anthropometric variables measured included height, weight, sitting height (SH), waist (WC), hip (HPC), thigh (TC), mid-upper arm (MUAC) and medial calf (MC) circumferences as well as triceps (TSF), biceps (BSF), subscapular SUBSF), suprailliac (SUPSF) and medial calf (MCASF) skinfolds. The results revealed, that there was a significant increasing age trend for all the anthropometric variables including the two derived variables: body mass index (BMI) and subischial leg length (SLL). For all variables, the lowest and the highest means were observed at the age of 6 and 9 years, respectively. The maximum increase in weight, BMI, all linear measurements, WC and HPC were observed during the period 6-7 years of age. In general, all skinfolds recorded similar yearly increments. More importantly, this study clearly indicated that among Bengalee girls aged 6-9 years, the highest amount of linear growth (height, SH and SLL) was observed at 6 years of age. The overall adiposity (BMI) also recorded the maximum increment during this period. The unique data presented here can be used as reference values for urban Bengalee Hindu girls aged 6-9 years.     

Sexual dimorphism in schoolchildren of the Villa IAPI neighborhood (Quilmes,Buenos Aires,Argentina)

Villa IAPI is a poor neighborhood of about 5,000 inhabitants in the overpopulated conurbano bonaerense at the outskirts of the city of Buenos Aires. Most of the adult male residents are construction workers; the rest are temporary workers, underemployed, or unemployed. The inhabitants of Villa IAPI suffer the effects of many adverse socio-economic conditions, including poor nutrition, deficient sanitation, and inadequate medical care. Seven anthropometric variables were measured on 765 children from 6 to 14 years old to test for the presence of an altered pattern of sexual dimorphism. It was found that there were practically no sex differences in standing height and upper-arm muscle circumference. In some age groups, there was a weak but significant sexual dimorphism in body weight and sitting height. The greatest and most persistent dimorphism was found in head circumference, and in triceps and subscapular skinfolds. In all except two age groups, head circumference in males was significantly greater than in females. The other dimorphic variables (body weight, sitting height, and triceps and subscapular skinfolds) showed the opposite relationship. Essentially, females showed increments in subcutaneous fat, while reduced growth in muscle and bone was evident in males. The hypothesis of “better female canalization” can explain the altered dimorphic pattern found in the malnourished Villa IAPI population. © 1993 Wiley-Liss, Inc.     

Urbanization disrupts latitude‐size rule in 17‐year cicadas

Many ectotherms show a decrease in body size with increasing latitude due to changes in climate, a pattern termed converse Bergmann's rule. Urban conditions—particularly warmer temperatures and fragmented landscapes—may impose stresses on development that could disrupt these body size patterns. To test the impact of urbanization on development and latitudinal trends in body size, we launched a citizen science project to collect periodical cicadas (Magicicada septendecim) from across their latitudinal range during the 2013 emergence of Brood II. Periodical cicadas are long‐lived insects whose distribution spans a broad latitudinal range covering both urban and rural habitats. We used a geometric morphometric approach to assess body size and developmental stress based on fluctuating asymmetry in wing shape. Body size of rural cicadas followed converse Bergmann's rule, but this pattern was disrupted in urban habitats. In the north, urban cicadas were larger than their rural counterparts, while southern populations showed little variation in body size between habitats. We detected no evidence of differences in developmental stress due to urbanization. To our knowledge, this is the first evidence that urbanization disrupts biogeographical trends in body size, and this pattern highlights how the effects of urbanization may differ over a species’ range.     

Body composition and fat distribution among older Jat females: A rural–urban comparison

The aim of the present cross-sectional study is to describe and compare age related changes in body composition and fat patterning among rural and urban Jat females of Haryana State, India. A total of 600 females (rural = 300, urban = 300), ranging in age from 40 to 70 years were selected by the purposive sampling method. Body weight, height, two circumferences (waist and hip) and skinfold thickness at five different sites (biceps, triceps, calf, subscapular, and supra-iliac) were taken on each participant. To study total adiposity, indices such as body mass index (BMI), grand mean thickness (GMT), total body fat and percentage fat were analyzed statistically. The fat distribution pattern was studied using waist/hip ratio, subscapular/triceps ratio and responsiveness of five skinfold sites towards accumulation of fat at different sites with advancing age. Results indicate a decline in almost every dimension including level of fatness between the mid-fourth and mid-fifth decades of life in both rural and urban females. Urban Jat females were heavier (57.36 kg vs. 56.07 kg, p > 0.05) and significantly taller (1553.3 mm vs. 1534.5 mm, p < 0.001) than their rural counterparts. Urban females also exhibited higher mean values for both the circumferences, five skinfold thicknesses as well as for lean body mass, total fat and percentage fat than the rural females. This is also evident from their higher mean values for body mass index and grand mean thickness. Waist/hip ratio values in rural and urban females showed upper body fat predominance, with urban females having relatively more abdominal fat. Results of subscapular/triceps ratio showed that rural and urban females gained proportionally similar amounts of subcutaneous fat at trunk and extremity sites until 45 years of age. Subsequently trunk skinfolds increased relatively more in thickness. The magnitude of this increase was comparatively greater in rural females up to 55 years and among urban females from 55 to 70 years. The profiles of subcutaneous fat accumulation and sensitivity of each skinfold site also revealed more fat deposition in the trunk region compared to extremities in both rural and urban females. The present study demonstrated differential rates of fat redistribution among rural and urban females.     

Ontogeny of shell morphology and shell strength of the marine snails Littorina obtusata and Littorina mariae: different defence strategies in a pair of sympatric, sibling species

The sibling marine snails Littorina obtusata (L.) and Littorina mariae Sacchi & Rastelli are sympatrically distributed and the shells of both species are subject to similar breaking forces by predatory crabs. Nevertheless, the two species exhibit rather different growth and defence strategies. To determine growth patterns, we measured changes in five morphological variables with increasing shell length: body whorl thickness at the point of crushing force application, shell height (related to globosity), shell mass, body mass, and apertural lip thickness. We also measured ontogenetic changes in the ability to withstand shell crushing. For most morphological variables, L. mariae showed uniformly allometric growth of juveniles into adults. In contrast, L. obtusata usually exhibited a distinct change in growth pattern upon reaching maturity. As adults, L. mariae showed a more sustained increase in overall shell mass and in body whorl thickness (defence against crushing attacks) and also had proportionally thicker apertural lips (defence against peeling attacks). Littorina obtusata , however, grew to a larger size and their shells could accommodate larger bodies at all sizes. Furthermore, the strength of L. obtusata shells increased faster than could be accounted for by either overall shell mass or thickness at the point of force application, suggesting strengthening by other means such as changes in shell microstructure or shape (other than globosity). These results illustrate the viability of two contrasting antipredator strategies, despite a highly similar phylogenetic history and selective regime.     

Childhood malnutrition and growth in a rural area of Western Kenya

An anthropometric survey was carried out on 1,383 school students aged 5-17 years in Suba district (a rural area of western Kenya). Body size and proportion were computed from height, weight, sitting height, arm circumference, and skinfolds. The aim of the study was to evaluate patterns of growth and nutritional status of the Luo population by assessment of the prevalence and trends of malnutrition among children and adolescents. Very few age-groups show significant sex differences for height, body weight, and arm muscle area. However, there are several differences in skinfold thicknesses and arm circumference, always with higher mean values in girls. Analysis of the nutritional status (weight-for-age, height-for-age, and BMI-for-age) shows significant differences among the age-groups in both sexes. Boys present lower Z-scores than girls and there are higher percentages of malnourished subjects (stunted and underweight) among the males. The Luo data were compared with those of other African populations. Their body dimensions, nutritional status, and growth are similar to those of the other sub-Saharan samples. In conclusion, the Luo children are generally undernourished at the older ages: adolescents (11-16 years of age) show the most severe undernutrition and the highest percentages of undernourished subjects. In addition to the higher risk of undernutrition in teenagers, an emerging problem of over-nutrition is evident among the younger age-groups, with a higher prevalence in females. These findings are discussed in light of sexual dimorphism in sensitivity to adverse environmental conditions.     

Growth of rural and urban children in the Valley of Oaxaca,Mexico

Weight, stature, arm circumference, and the triceps skinfold were measured in 1,410 school children, 6 through 14 years of age, from two urban colonias in the city of Oaxaca de Juarez (n = 479), and from two rural Ladino (n = 467) and two rural Zapotec (n = 464) communities in the Valley of Oaxaca in southern Mexico. Children from rural Ladino communities and urban colonias are significantly taller, heavier, and more muscular than children in rural Zapotec communities. The differences between rural Ladino and urban colonia children favor the former, particularly for weight and stature. These observations thus suggest (1) that children in the rural, indigenous communities in the Valley of Oaxaca are relatively undernourished compared to children in Ladinoized and urban communities, and (2) that rural-to-urban migration does not necessarily result in improved growth status.     

Growth of rural and urban children in the valley of Oaxaca,Mexico

Weight, stature, arm circumference, and the triceps skinfold were measured in 1,410 school children, 6 through 14 years of age, from two urban colonias in the city of Oaxaca de Juarez (n = 479), and from two rural Ladino (n = 467) and two rural Zapotec (n = 464) communities in the Valley of Oaxaca in southern Mexico. Children from rural Ladino communities and urban colonias are significantly taller, heavier, and more muscular than children in rural Zapotec communities. The differences between rural Ladino and urban colonia children favor the former, particularly for weight and stature. These observations thus suggest (1) that children in the rural, indigenous communities in the Valley of Oaxaca are relatively undernourished compared to children in Ladinoized and urban communities, and (2) that rural-to-urban migration does not necessarily result in improved growth status.     

Evidence of genetic influence on central body fat in middle-aged twins

The heritability of centrally and peripherally deposited subcutaneous body fat, as measured by thickness of subscapular and triceps skinfolds respectively, was examined in 173 monozygotic and 178 dizygotic pairs of white male twins, ages 54 to 65 years, who participated in the second examination of the National Heart, Lung, and Blood Institute's Twin Study. The heritability of two indices of body fat distribution (subscapular/triceps ratio and subscapular-triceps difference) and two indices of overall obesity (body mass index and sum of skinfolds) were also assessed. Evidence for a genetic influence on central deposition of body fat was suggested in that the classical estimate of heritability for subscapular skinfold thickness was 0.77 (p less than 0.0001). After adjusting subscapular skinfold for the overall level of obesity, heritability was reduced but remained highly significant (0.40, p = 0.003). Heritability estimates for triceps skinfold thickness and for the two fat distribution indices were substantially lower and were not statistically significant after adjustment for overall obesity. High classical estimates of heritability were also observed for both measures of overall obesity: 0.70 for BMI and 0.73 for sum of skinfolds. However, these two estimates were biased upward because of lower total variances among monozygotic compared to dizygotic twins in this sample. The more conservative and unbiased among-component estimates also suggested substantial heritability for each measure (0.35, p = 0.08 and 0.53, p = 0.01, respectively). The heritability of overall obesity emphasizes the importance of adjusting measures of fat distribution for overall obesity before assessing its heritability.     

Developmental pattern formation of somatic embryos induced in cell suspension cultures of cowpea [Vigna unguiculata (L.) Walp]

The sequence of events in the functional body pattern formation during the somatic embryo development in cowpea suspensions is described under three heads. Early stages of somatic embryogenesis were characterized by both periclinal and anticlinal cell divisions. Differentiation of the protoderm cell layer by periclinal divisions marked the commencement of somatic embryogenesis. The most critical events appear to be the formation of apical meristems, establishment of apical-basal patterns of symmetry, and cellular organization in oblong-stage somatic embryo for the transition to torpedo and cotyledonary-stage somatic embryos. Two different stages of mature embryos showing distinct morphology, classified based on the number of cotyledons and their ability to convert into plantlets, were visualized. Repeated mitotic divisions of the sub-epidermal cell layers marked the induction of proembryogenic mass (PEM) in the embryogenic calli. The first division plane was periclinally-oriented, the second anticlinally-oriented, and the subsequent division planes appeared in any direction, leading to clusters of proembryogenic clumps. Differentiation of the protoderm layer marks the beginning of the structural differentiation in globular stage. Incipient procambium formation is the first sign of somatic embryo transition. Axial elongation of inner isodiametric cells of the globular somatic embryo followed by the change in the growth axis of the procambium is an important event in oblong-stage somatic embryo. Vacuolation in the ground meristem of torpedo-stage embryo begins the process of histodifferentiation. Three major embryonic tissue systems; shoot apical meristem, root apical meristem, and the differentiation of procambial strands, are visible in torpedo-stage somatic embryo. Monocotyledonary-stage somatic embryo induced both the shoot apical meristem and two leaf primordia compared to the ansiocotyledonary somatic embryo.     

Differences in nutritional status between rural and urban Yucatec Maya children: The importance of early life conditions

Early-life conditions shape childhood growth and are affected by urbanization and the nutritional transition. To investigate how early-life conditions (across the “first” and “second” 1000 days) are associated with rural and urban children's nutritional status, we analyzed anthropometric data from Maya children in Yucatan, Mexico. We collected weight, height and triceps skinfold measures, then computed body mass and fat mass indices (BMI/FMI), in a cross-sectional sample of 6-year-olds (urban n = 72, rural n = 66). Demographic, socioeconomic and early-life variables (birthweight/mode, rural/urban residence, household crowding) were collected by maternal interview. We statistically analyzed rural-urban differences in demographic, socioeconomic, early-life, and anthropometric variables, then created linear mixed models to evaluate associations between early-life variables and child anthropometric outcomes. Two-way interactions were tested between early-life variables and child sex, and between early-life variables and rural-urban residence. Results showed that rural children were shorter-statured, with lower overweight/obesity and cesarean delivery rates, compared to urban children. Household crowding was a negative predictor of anthropometric outcomes; the strongest effect was in boys and in urban children. Birthweight positively predicted anthropometric outcomes, especially weight/BMI. Birth mode was positively (not statistically) associated with any anthropometric outcome. Cesarean delivery was more common in boys than in girls, and predicted increased height in urban boys. In conclusion, urbanization and household crowding were the most powerful predictors of Maya 6-year-old anthropometry. The negative effects of crowding may disproportionately affect Maya boys versus girls and urban versus rural children. Early-life conditions shape Maya children's nutritional status both in the “first” and “second” 1000 days.     

Energy allocation in juvenile sablefish: effects of temperature, ration and body size

The lipid deposition of juvenile sablefish Anoplopoma fimbria was examined, in particular, the changes in allocation over time. Growth rates of early juveniles (initial size 36–50 mm total length, L_T) were manipulated using two temperatures (10 and 20° C) and two rations (ad libitum and 3–4% body mass day^?1). Fish L_T, mass and lipid content were measured every 3 weeks for 15 weeks. Irrespective of treatment, the relationship of total lipid content with body size was clearly hyperallometric; small juveniles allocated relatively more energy to growth and less to lipid storage than large juveniles. After adjusting for the influence of body size, temperature and ration significantly influenced body composition but these effects varied over the course of the experiment. In the first 3 week time period, fish on the high ration, high temperature treatment had reduced lipid storage relative to other treatments, but in all subsequent time periods their lipid concentrations were similar to or higher than those of fish on other treatments. In contrast, fish held at low rations and low temperatures initially had average levels of lipid concentration, but after 6 weeks their levels were lower than other treatments. Estimation of allocation to lipid storage over time (proportion of dry mass increase comprised of lipid) suggested that fish in all of the treatments were approaching an asymptotic level of lipid concentration (c. 50–60% of dry mass) but with different rates of lipid increase. Within a treatment, it was predicted that individual differences in allocation would result in trade‐offs between somatic growth and storage. This trade‐off was evident only for fish held on low rations at low temperatures. In contrast, fish held on high rations at high temperatures exhibited the opposite pattern of a positive correlation between somatic growth and storage. These results suggest that lipostatic regulation of appetite is unlikely in juvenile sablefish. When resources are unlimited, this species appears to adopt a maximizing strategy for both somatic growth and lipid accumulation.     

Postnatal Dynamics of Developmental Stability and Canalization of Lizard Head Shape Under Different Environmental Conditions

Developmental stability (DS) and canalization are key determinants of phenotypic variation. To provide a better understanding of how postnatal growth is involved in determining the effects of DS and canalization on phenotypic variation, we studied within- and among-individual variation in head shape in ontogenetic series of lizards inhabiting urban and rural environments. Urban lizards exhibited increased fluctuating asymmetry during the early postnatal stages, but asymmetry levels decreased during growth. By contrast, asymmetry remained constant across the investigated size range in the rural population. In addition, urban juveniles were more variable for symmetric shape and deviated more from the group shape-size allometric trajectory, but both indices declined across ontogeny. Congruent patterns of within- and among-individual variation suggest that both DS and canalization may rely on similar underlying mechanisms. Further, the ontogenetic reduction of variation in the urban population suggests that compensatory growth may aid in buffering phenotypic variation and correcting deviances from the established developmental path. Alternatively, passive mechanisms and population dynamics may also explain the decrease of phenodeviants in urban populations. Significant correlations between symmetric and asymmetric shape, as well as similar integration patterns between the two populations, suggest that similar developmental mechanisms regulate head shape in both environments. Overall, these results highlight the relevance of both pre- and post-natal dynamics in determining levels of phenotypic variation, enhancing our understanding of how organisms respond to perturbations to DS and canalization under stressful conditions.     

Heritability variations of body linearity and obesity indicators during growth

Longitudinal as well as cross-sectional studies have shown variations with age in heritability estimates for body dimensions from infancy to adulthood, even though the patterns of variation are not completely clear. Further study on this subject is of great interest and may help obesity interventions for preventing or treating obesity in children. Therefore, the aim of the present study is to analyse the changes in the genetic and environmental architecture of 8 body linearity and obesity-related phenotypes during the growth process in a cross-sectional sample of 1018 nuclear families from the province of Biscay (Basque Country, Spain). The contribution of additive genetic effects to the variation of the analysed traits was estimated by a variance component analysis using the SOLAR program. Moderate to high heritability estimates were obtained for all 8 anthropometric phenotypes (38.23–65.98%). The heritability values show an increasing trend with age and in the course of the entire ontogenetic development two age periods were remarkable. At 7⁺–8⁺ years of age a strong increase in heritability estimates was found for all the anthropometric phenotypes, except for the sum of skinfolds (SF6), reflecting the biological significance of genes during mid-childhood. During puberty, most of the obesity related phenotypes showed their highest heritability values while linear measurements and weight presented a decrease in the genetic contributions. In conclusion, this study confirms that additive genetic influences have a considerable effect on body linearity and obesity-related traits throughout the growth period and that mid-childhood and puberty are very sensitive periods in human life cycle.     

Determinants of variation in adult body height

Final body height is achieved as the result of a combination of genetic and environmental factors. The aim of this article is to review past studies on body height that have followed different scientific traditions. In modern Western societies, about 20% of variation in body height is due to environmental variation. In poorer environments, this proportion is probably larger, with lower heritability of body height as well as larger socioeconomic body height differences. The role of childhood environment is seen in the increase in body height during the 20th century simultaneously with the increase in the standard of living. The most important non-genetic factors affecting growth and adult body height are nutrition and diseases. Short stature is associated with poorer education and lower social position in adulthood. This is mainly due to family background, but other environmental factors in childhood also contribute to this association. Body height is a good indicator of childhood living conditions, not only in developing countries but also in modern Western societies. Future studies combining different scientific traditions in auxology are needed to create a more holistic view of body height.