To assess the relationship between telomere length and adiposity, using dual-energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI), in addition to conventional anthropometric proxies including body mass index (BMI) and cardiovascular disease risk factors.
A cross-sectional sample of 309 non-Hispanic white participants in the Fels Longitudinal Study aged 8 to 80 yr (52% female) was included. Average telomere length was measured by quantitative PCR.
Telomere length was negatively correlated with age (r = -0.32, P < 0.0001) and had numerous significant correlations with established cardiovascular disease risk factors including waist circumference (r = -0.33), apolipoprotein B (r = -0.26), systolic blood pressure (r = -0.28), and fasting serum glucose (r = -0.15); all P < 0.0025. In backward selection linear regression models of telomere length, adiposity measures were consistently retained in the best models; BMI, waist circumference, hip circumference, total body fat, and visceral adipose tissue volume were all inversely associated with telomere length at the nominal P < 0.05 level or lower, independent of age, sex, systolic blood pressure, and fasting serum lipid, lipoprotein, and glucose concentrations. The negative association of BMI with telomere length was stronger among younger than older participants (P for interaction, 0.03).
Individuals with higher total and abdominal adiposity have lower telomere length, a marker of cellular senescence, suggesting obesity may hasten the aging process. Longitudinal studies are required to establish the causal association of early life adiposity with biological aging.
Mean stature in a population has been observed to vary with living conditions. If, and how, this affects sexual dimorphism in stature is not fully understood. We analyzed stature data from Swedish populations from the 10th to the end of the 20th century to investigate if male stature is more plastic than female stature in response to environmental changes. Further, we examined if there, as a consequence of this, exists an allometric relationship between male and female stature that is not caused by genetic factors, coupling greater stature with greater dimorphism. We found no significant change in stature from the 10th century to the 17th century, but a clear increase in both male and female stature during the 20th century, most likely because of improved living conditions. Regression analyses revealed no consistent change in sexual stature dimorphism over time for any of the time periods, including the 20th century. Further, we found no significant allometric relationship between male and female stature, and could consequently not identify any significant relationship between stature and stature dimorphism. Thus, contrary to previous suggestions, the regressions did not provide support for the assertion that male stature is more sensitive to environmental changes than female stature, nor that stature dimorphism increases with increasing stature.
The age-related pattern of body density and body composition in Japanese males (n = 266) and females (n = 318), 11.00 to 18.99 years of age was studied. Body density (BD) as well as height, body weight, and seven skinfold thicknesses were measured. Percentage fat (%Fat) was calculated using the age- and sex-specific equation of Lohman. Fat mass (FM), fat-free mass (FFM), and the body mass index (BMI) were calculated. The trend for BD in males was lowest at 11 years (1.0530 g/ml) and increased to 1.0695 g/ml at 14 years, and then decreased slightly at 15 to 17 years. In female, BD decreased from 1.0530 g/ml at 13 years to 1.0424 g/ml at 17 years. Mean %Fat was highest in males at 11 years (15.8%), and lowest at 14 years (10.1%). The highest mean %Fat in females occurred at 16 years (22.8%), and the lowest at age 11 years (15.2%). Overall, only 6.8% of males and 3.1% of females were classified as obese. Between 11 and 18 years, FFM of males differed by 20.7 kg or 67.9%, whereas females showed a difference of only 10.8 kg or 34.7%. Consequently, age effects explained approximately 60% of the male variance of FFM but only 26% in females. Body density of each sex and age group in this study did not differ significantly from previous Japanese studies, and the pooled BD data for 1,457 Japanese including the present study are reported as a reference.
Project HeartBeat! is a four year mixed-longitudinal study of the development of cardiovascular risk factors in White and African American children who at baseline comprised three age cohorts 8, 11, and 14 years. This paper focuses on the anthropometric variables which were chosen to reflect body fat and fat-free mass. Selected anthropometric dimensions are compared with those of samples from the combined National Health and Nutrition Examination Surveys I and II to explore the similarities of the samples in terms of central tendencies and variances. The measurements were then explored in terms of their ability to estimate the two compartment model of body composition: fat-free mass (FFM) and body fat (BF) from bioelectrical impedance (BIA). Project HeartBeat! children are slightly larger than NHANES children and have variances that are generally comparable to the national surveys. Over seven percent (7.7%) of children were overweight (BMI) and 25% had 'mild obesity' by %BF. Three different factor analytic methods (incomplete principal components, alpha and maximum likelihood) produced two latent variables from 17 anthropometric dimensions which together accounted for 76-83% of the variation: (1) A body mass factor (F1) which was weighted highly on six circumferences, weight and six skinfolds, and (2) a linear growth factor (F2) which was strongly associated with height, arm length, and sitting height. Triceps, subscapular and midaxillary skinfolds were consistently highly loaded on the body mass factor and their sum was highly correlated to %BF and fat mass (0.90-0.99). This suggests that this sum could be used to estimate fatness in children in studies where the BIA or other body composition techniques are unavailable. FFM and %BF were predicted from the anthropometric factors. Both factors contributed to the estimate of FFM (R(2) = 0.81-0.93), although F2 contributed proportionately more. The 'body mass' factor (F1) was the main predictor of %BF (R(2) = 0.86-0.93), though at some ages the linear factor (F2) was significantly and negatively related to %BF. This set of anthropometric dimensions, taken for the purpose of estimating body composition and summarized as two latent vectors by factor analysis, strongly reflects body fat and FFM in children and adolescents. Am. J. Hum. Biol. 11:69-78, 1999. Copyright 1999 Wiley-Liss, Inc.
The purpose of this study was to investigate patterns of physical activity and levels of inactivity in adolescent females in the United Arab Emirates (UAE). A total of 58 adolescent females, age 11-16 years, were recruited from two female-only governmental schools in Abu-Dhabi. Subjects were divided into two groups: 11-13 years (n = 22) and 14-16 years (n = 36). Physical activity patterns were determined from a 3-day activity diary. Total energy expenditure (TEE) was estimated using a factorial approach. The amount of physical activity was expressed as the physical activity level (PAL) and the activity-related energy expenditure (AEE). The number of hours spent watching television was estimated from the activity diaries. There were no significant differences in the energy expenditure parameters between age groups or between schooldays and weekends. PAL was low in both age groups. Television was the predominant leisure time pursuit. The number of hours per day spent watching television (median and interquartile range) was 2.5 (2.3-3.1) in 11-13 years and 2.5 (2.3-2.8) in 14-16 years. Television-watching was significantly higher during the weekend than schooldays: 11-13 years (P = 0.006) and 14-16 years (P < 0.001). In conclusion, the amount of physical activity undertaken by adolescent females in the UAE was very low. Cultural and weather restrictions and social change of the community in the UAE are not conducive to physical activity and play a major role in levels of physical inactivity. This may explain, in part, the rise in the incidence of obesity in this population.
There is an apparent link between fetal and childhood growth and puberty and risk for several degenerative diseases in adulthood. It is also important to consider associations between birth weight and indicators of growth and biological maturation during childhood and adolescence as potential explanations for associations between fetal growth and adult risk for disease. The present study examines the association between birth weight and (1) size attained and rate of growth in body size and cortical bone area of the second metacarpal (M II), and (2) skeletal age and rate of skeletal maturation in children 6-11 years of age. The sample included 127 boys and 105 girls of European ancestry, divided into two age groups, 6-8 years and 9-11 years. The relationship between birth weight and attained size (stature, mass, and the BMI), M II cortical area and skeletal age (SA, Tanner-Whitehouse method) during childhood was examined with correlational analyses. Observations on children measured on two occasions were converted to annual velocities, and correlations between birth weight and annual velocities were also calculated. Birth weight is significantly associated with stature and mass in boys and only with stature in girls 6-11 years of age, but is not related to the BMI, M II cortical area, or skeletal maturity. Birth weight is not significantly related to annual velocities of growth in stature, mass, the BMI and M II cortical area; to the annual increment in SA; and to weight gain from birth to the time of measurement (intervals of 6 to 11 years). The results emphasize a role of other influences than birth weight on growth rate, cortical area of M II, and skeletal maturation during childhood. Am. J. Hum. Biol. 11:505-511, 1999. Copyright 1999 Wiley-Liss, Inc.
This study tested hypotheses that: (1) levels of adiposity, as assessed by triceps and subscapular skinfold thicknesses (SFTs), and blood pressure would be higher in British Pakistani children than in white British children; and (2) British Pakistani children of mothers born in the UK would have smaller SFTs and lower blood pressure than children of mothers born in Pakistan.
Participants aged 7 to 11 years were recruited from five primary schools in a deprived urban area. BMI, waist circumference, triceps and subscapular SFT, and blood pressure were measured.
Participants comprised 209 white British and 132 British Pakistani children, including 79 children born in the UK to migrant mothers and 49 children born to British-born mothers. In comparisons by ethnic group, triceps SFT was significantly higher in British Pakistani children only after controlling for BMI. Subscapular SFT was higher in British Pakistani children, a finding strengthened after controlling for BMI. Systolic blood pressure was significantly higher in British Pakistani children, but not after controlling for socioeconomic status (SES). There were no significant differences between British Pakistani children born to migrant or British-born mothers, except that systolic blood pressure was lower in children of British-born mothers after controlling for SES, a finding that was not significant after controlling for BMI.
This study confirms previous findings of larger SFTs and higher blood pressure in British children of Pakistani origin than in children of white European origin. Further work with larger sample sizes is needed to investigate differences between generations.
C-reactive protein, a marker of chronic, low-grade inflammation, is strongly associated with current central adiposity, and has been linked to elevated risk of cardiovascular disease. Less is known about the contribution of longitudinal change in waist circumference to current inflammation. We evaluated the extent to which current waist circumference and change over an 11-year interval contribute independently to low-grade systemic inflammation measured in a group of 1,294 women, 35-69 years, participating in the Cebu Longitudinal Nutrition and Health Survey in the Philippines. Waist circumference was measured at the time of blood draw for CRP analysis in 2005 and during an earlier survey in 1994. A waist circumference delta variable was constructed by subtracting current circumference from past circumference. We used logistic regression models to predict having an elevated plasma CRP concentration (3 mg L(-1) < CRP < 10 mg L(-1)). Waist circumference in 2005 was a strong predictor of elevated CRP (OR 1.10, 95% CI = 1.08, 1.12, P < 0.001). In combined models, increase in circumference over 11 years was a significant and independent predictor of elevated CRP risk (OR = 1.023, 95% CI = 1.00, 1.05, P < 0.05). Considering the average increase over time, the cumulative risk of elevated CRP due to increased central adiposity was 25.7%. However, women who reduced their waist circumference between 1994 and 2005 had greatly reduced risk (6.2%), suggesting that even long-term inflammatory burden can be reversed by weight loss. Although current waist circumference is an important contributor to risk of elevated systemic inflammation in this as in other populations, history of central adiposity may be an independent phenomenon.
Tetrameric short tandem repeat (STR) polymorphisms are widely used in population genetics, molecular evolution, gene mapping and linkage analysis, paternity tests, forensic analysis, and medical applications. This article provides allelic distributions of the STR loci D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, CSF1PO, TPOX, TH01, and D16S539 in 143 Mestizos from Northeastern Mexico, estimates of contributions of genes of European (Spanish), American Indian and African origin in the gene pool of this admixed Mestizo population (using 10 of these loci); and a comparison of the genetic admixture of this population with the previously reported two polymorphic molecular markers, D1S80 and HLA-DQA1 (n = 103). Genotype distributions were in agreement with Hardy-Weinberg expectations (HWE) for almost all 13 STR markers. Maximum likelihood estimates of admixture components yield a trihybrid model with Spanish, Amerindian, and African ancestry with the admixture proportions: 54.99% +/- 3.44, 39.99% +/- 2.57, and 5.02% +/- 2.82, respectively. These estimates were not significantly different from those obtained using D1S80 and HLA-DQA1 loci (59.99% +/- 5.94, 36.99% +/- 5.04, and 3.02% +/- 2.76). In conclusion, Mestizos of Northeastern Mexico showed a similar ancestral contribution independent of the markers used for evolutionary purposes. Further validation of this database supports the use of the 13 STR loci along with D1S80 and HLA-DQA1 as a battery of efficient DNA forensic markers in Northeastern Mestizo populations of Mexico.
Socioeconomic variation in the growth status of urban school children 6-13 years of age in 1972 and 2000 was compared. The children were resident in the city of Oaxaca and were students in the same primary school in each year. Socioeconomic status (SES) was based on parental occupation. Height, sitting height, estimated leg length, weight, and the body mass index in 218 boys and 191 girls in 1972 and 173 boys and 166 girls in 2000 were compared. Sex-specific MANCOVA was used to evaluate SES differences within each year, while sex- and SES-specific MANCOVA was used to evaluate differences between years. The prevalence of stunting, overweight and obesity was estimated. There were no SES differences among boys and girls in 1972 and boys in 2000; low-middle and middle SES girls were significantly taller and heavier with longer legs than low SES girls in 2000. Within each SES group, children in 2000 were significantly larger in body size and segment lengths except for sitting height in low SES children of both sexes. Estimated secular gains increased from low to low-middle to middle SES in both sexes. Inequitable gains by SES contributed to an increase in the magnitude of differences between SES groups, especially between low SES children on one hand and low-middle and middle SES children on the other hand. The prevalence of stunting declined while the prevalence of overweight and to a lesser extent in obesity increased from 1972 to 2000, more so in low-middle and middle SES than in low SES children.
We investigated the occurrence and intra-allelic variability of the T(-13910) variant located upstream of the lactase gene in 965 individuals from 20 different locations of Italy and Greece. The T(-13910) frequency ranges from 0.072 (Sardinia) to 0.237 (North-East Italy), with a statistically significant difference between North-East Italians and other Italian populations. The comparison of the lactose tolerance predicted by T(-13910) and that assessed by other studies using physiological tests shows a one-way statistically significant discrepancy that could be due to sampling differences. However, the possible role of other genetic factors underlying lactase persistence is worth exploring. The time of the most recent common ancestor and departures from neutrality of the T(-13910) allele were assessed using three microsatellite loci. Time estimates were found to be congruent with the appearance of dairy farming in Southern Europe and the occurrence of a single introgression event. Robust signals of selection can be observed in North-East Italy only. We discuss the possible role of cultural traits and genetic history in determining these observed micro-evolutionary patterns.
The present study is part of a research project on growth models of children in an area of central-southern Italy. It analyzes the phases of pubertal breast development (BD) in 397 girls, pubic hair development (PHD) in 399 girls, and menarche in 583 girls from 6-14 years old. The status quo method was used to evaluate the age at menarche. Probit analysis was used to analyze the data for all three variables. The onset of BD and PHD (Tanner stage 2) occurs at age 7 in 6.1% of girls. Passage to stage 3 of one or both secondary sexual characteristics occurs at age 10 in 8.5% of girls. Comparison with data from the United States shows higher percentages of American white girls in stage 2 (or greater) of both characteristics at any age. The mean (median) age of onset (Tanner stage 2) of BD or PHD or both of them is 9.96 years. The passage to stage 3 occurs at age 12.36 for BD (95% confidence interval: 1.36 years) and at age 12.10 for PHD (95% confidence interval: 0.51 years). The mean age at menarche is 12.55 years, in general agreement with other values found in Italy. Sexual maturation at any considered stage for both pubertal characteristics is generally in line with literature data concerning other Mediterranean and industrialized countries or countries in which the demographic transition is in an advanced phase. It does not show a significant earlier onset. The evidence emerging from the general project suggests that the secular trend is still in progress in this region of Italy.
Obesity has reached epidemic proportions in the U.S. and more developed countries, particularly so among adolescents. A substantial impact on public health could be achieved if other factors causing obesity besides the conventional ones of diet and physical activity could be identified and acted upon. The present study investigates whether there is a link between low sleep quality and obesity in a tri-ethnic, cross-sectional sample (n = 383) of male and female adolescents ages 11-16 years old (Heartfelt Study). Sleep quality was expressed as two variables, total sleep time and sleep disturbance time obtained by 24-hour wrist actigraphy. Percent body fat and body mass index (BMI) were used together to define obesity. The potential influence of demographic and behavioral confounders were considered in models that described the relation of sleep to obesity occurrence. Obese adolescents experienced less sleep than nonobese adolescents (P < 0.01). For each hour of lost sleep, the odds of obesity increased by 80%. Sleep disturbance was not directly related to obesity in the sample, but influenced physical activity level (P < 0.01). Daytime physical activity diminished by 3% for every hour increase in sleep disturbance. The above observations were independent of potential confounding variables. Inadequate and poor sleep quality in adolescents may be important factors to consider in the prevention of childhood obesity.
The purpose of the study reported here was to further investigate a new method of estimating inbreeding in large, relatively isolated populations over historic times, as reported by Pattison (1999, 2001). The method is based on modeling the genealogical "paradox" and produces values of Pearl's coefficients of inbreeding as a function of time for any given population curve. In particular, this study demonstrates that the new method of estimating inbreeding may be used to examine the effect of unusual features in population curves on levels of inbreeding in that population. As an example, the medieval population "bump" that spans the 13th and 14th centuries in the population of Britain, which terminated abruptly with the outbreak of bubonic plague in 1348 AD, is examined. It is first assumed that the whole population was the adult (breeding) population, corresponding to minimum inbreeding. For this case it is found that, for distant generations, about 90% of the whole population occurs in any present-day British pedigree. This value compares favorably with the values of 85% and 80% reported by Wachter (1980) and Derrida et al. (1999, 2000), respectively. The population bump causes the curves for Pearl's coefficient, for minimum inbreeding, to have a plateau of about 96% over the period from about 1220 AD to 1380 AD. The effect of introducing a single known estimate of inbreeding into the model is to produce a more realistic situation where the adult (breeding) population is considerably less than the whole population. It is found that the maximum number of different ancestors in any generation, in the average British pedigree, is about 22900 individuals and occurs about 1220 AD. More importantly, and possibly contrary to expectation, it is now found that the population bump had virtually no effect on the level of inbreeding.
The aim of this study was to assess the prevalence of overweight and obesity in Portuguese children age 7-9 years and to analyze trends in body mass index (BMI) from 1970-2002. Data were collected from October 2002 to June 2003 in a random sample of Portuguese children. Height and weight were measured and BMI (Kg/m(2)) was calculated. The International Obesity TaskForce (IOTF) cutoffs to define overweight and obesity were used. In the total sample we found 20.3% of overweight children and 11.3% of obese children. These results indicate a prevalence of overweight/obesity of 31.5%. Girls presented higher percentages of overweight than boys except at age 7.5. Girls also showed a higher percentages of obesity than boys except at age 9. From 1970 to 1992 and 1992 to 2002, height, weight, and BMI increased at different velocities: weight increased faster than height, and, consequently, BMI increased more in the last period than in the first one, leading to an increase in obesity values. Compared to published data by IOTF on other European countries, who applied the same methods to define overweight and obesity, Portuguese children showed the second-highest mean values in overweight/obesity. Italy showed the highest values (36%). The present study shows a very high prevalence of overweight/obesity (31.5%) in Portuguese children compared to other European countries. Portugal followed the trend of other Mediterranean countries like Spain (30%), Greece (31%), and Italy (36%). These high values require a national intervention program to control childhood obesity.
Little data are available on the growth and development of young female dancers. The objective of this study was to determine whether the body structure and adipose tissue distribution of dancers aged 8-16 years differ from that of non-dancer girls. Our cross-sectional study included a group of 1,482 female dancers, aged 8-16 years, and a control group of 226 female non-dancers of similar age cohorts. Fourteen anthropometric measurements were recorded and 15 indices calculated. In none of the linear anthropometric measures, were significant differences found between the two groups. The only significant difference relates to the extent and distribution of adipose tissue: At age 8, both groups show similar weight while at age 13 non-dancers are significantly heavier than dancers (48.4 +/- 9.8 kg for non-dancers and 40.6 +/- 8.7 kg for dancers). At age 15, weight differences between the two groups decrease to only 2 kg. The differences in weight are also expressed in skinfold thickness and chest circumference. Patterns of adipose tissue distribution differ between the two groups. Mean age at menarche was 13.1 years among dancers and 12.3 years in non-dancers. In conclusion, musculoskeletal development was found to be very similar in dancers and non-dancers. The specific body type reported for professional dancers is more likely acquired via "teacher's selection" and not training programs. Parents should not dread the possibility that dance training will delay the growth or reduce the height of their daughters.
Coefficients of relationship by isonymy, based on the frequency of common surnames, were used to estimate the biological affinity between (R(ib)) and within (R(iw)) 16 Sardinian villages in the periods 1825-1849, 1875-1899, and 1925-1949. The database for the surname analysis consisted of 13,515 marriages registered in the parishes of villages, all belonging to the Sardinian linguistic area. The values of R(ib) and R(iw) tend to decrease in time. In all three periods, the R(ib) values generally decrease as the geographical distance between villages increases. The negative values of the Bravais-Pearson coefficient of correlation between the matrix of R(ib) values and the matrices of geographical distances (calculated both in a straight line and from road distances) are significant for each period (modified Mantel test), with slightly higher correlation coefficients for road distances. Moreover, the plots of isonymic relationships obtained by nonmetric multidimensional scaling for 1825-1849 and 1925-1949 show that the biological relationships between neighboring villages increase in the latter period. The positive values of the Bravais-Pearson coefficients of correlation between R(iw) and altitude are significant in all three periods, while the correlation between R(iw) and population size is not significant, even when altitude is controlled for. Since altitude is considered an indicator of isolation, the results obtained with the coefficient of relationship by isonymy within villages also support the isolation-by-distance model. R(ib) values provided a reliable picture of the biological relationships between 16 Sardinian villages, while R(iw) values illustrated the biological affinity within the communities for a period of 100 years, from 1825-1849 to 1925-1949.
The purpose of the present study was to assess the age differences in growth characteristics and physical abilities of physically active adolescent girls and to compare them to corresponding data for girls nonactive in sport. The cross-sectional study was carried out on 643 Estonian girls, 10-17 years of age, who were regularly training track and field, and 902 nonactive girls. The organized physical activity of the studied girls consisted of lessons in the school curriculum (2 x 45 minutes per week) for both groups and special track and field training for the first group. Height, weight, and the body mass index (BMI) were used to characterize growth status. Physical ability was assessed with the 30-m dash, standing long jump, medicine ball throw (2 kg), standing quintuplet jump, isometric strength of back extensor muscles, and 1-minute ergocycling at the highest possible rate. Girls active in track and field were taller in all the age groups (P < 0.05-0.001) and lighter except at 17 years, when they were heavier (P > 0.05), but the differences at 12 and 13 years were not significant. BMI was also significantly lower in active girls (P < 0.05-0.001) in all age groups, except at 17 (P > 0.05). The actively training girls had higher physical abilities at all ages from 10-17. The annual differences in performance scores were significant (P < 0.05-0.001) up to 15 years except for the standing long jump. Differences in mean scores of most motor abilities were minimal or reduced significantly at 13-14 years in nonactive girls, but were significant in active girls.
Reference percentiles (5th, 10th, 50th, 85th, 90th, and 95th) of black and nonblack children ages 8-17 years from Project HeartBeat! (n = 678) are presented for body mass index (BMI), percent body fat (PBF), fat-free mass (FFM), and fat mass (FM) derived from bioelectrical impedance. Project HeartBeat! is a mixed longitudinal study in which three cohorts of children (seen initially at age 8, 11, or 14 years) were followed for 4 years and measured thrice-yearly from 1991 through 1995. Weight, height, and BMI of Project HeartBeat! children are similar in central tendency and variability to those of nationally representative samples for nonblack children but not black children, for whom there is an excess of children at or above the 95th percentile for weight and BMI. Values of PBF above which cardiovascular risk variables increase (as suggested in the literature) are located at the 85th percentile of the Project HeartBeat! distributions. This percentile of PBF may be tentatively considered as a cutoff point with epidemiological significance for children.
The purpose of the study was to develop ethnic-specific equations for fat-free mass (FFM) from selected anthropometric dimensions and bioelectrical impedance measures of resistance (R) and reactance (Xc) for use in the NHLBI Growth and Heath Study. Using dual-energy X-ray absorptiometry measures of body composition as the dependent variable and field measures of body composition by anthropometry and bioelectrical impedance as the explanatory variables, ethnic-specific prediction equations were developed on a sample of girls representing a wide range of ages and BMI. The equations were cross-validated using (1) the Prediction of Sum of Squares (PRESS) statistic and (2) an independent sample of 20 girls of each race from a study conducted at the National Institute of Child Health and Human Development (NICHD). Subjects were 65 White and 61 Black girls 6-17 years of age. The best race-specific equations for FFM each explained 99% and 97% of the variance in the White and Black girls, respectively. Root mean square errors (RMSE) ranged from 1.14 to 1.95 kg. The equation for Black girls used Stature2/Resistance (R), weight, and reactance (Xc) as predictor variables; the equation for White girls used Stature2/R, weight, and triceps skinfold thickness. The results indicate that (1) equations to predict FFM in girls should be ethnic-specific and that (2) accurate values for TBF and %BF can be calculated from the predicted FFM.
The observation that declines in the human secondary sex ratio (SSR) may be linked to stressful periconceptional periods has received considerable attention (Catalano  Hum Reprod 18:1972-1975; Catalano et al.  Int J Epidemiol 34:944-948,  Hum Reprod 20:1221-1227,  Paediatr Perinat Epidemiol 19:413-420). For the purpose of testing the external validity of this phenomenon, birth records from four German village genealogies (N = 1,048) were analyzed to study the impact of the French Revolutionary Wars (1787-1802) on the proportion of male births. All births were subdivided into three cohorts (prewar, 1787-1792; war, 1792-1797; and postwar, 1797-1802). Differences in SSR between cohorts achieved statistical significance (chi2= 7.695; df = 2; P = 0.021). In addition, changes in SSR before, during, and after the wars were monitored by risk analysis. Using the SSR of the prewar period as a control, the results of the war cohort failed to achieve statistical significance (regression coefficient, -0.257; ExpB= 0.773; P = 0.118), while the odds reduction of 32.3% in the postwar period proved to be statistically significant (regression coefficient, -0.390; ExpB= 0.677; P = 0.006). It is hypothesized that the experience of postwar economic hardship (attributable to lowered food availability paired with dietary changes) represents the most likely proximate cause. The study also finds evidence of a parental sex ratio manipulation strategy meant to offset the female-biased SSR after the wars. It is argued that from an evolutionary perspective both the decline in SSR in response to stress as well as parental manipulation of the tertiary sex ratio convey reproductive advantages.
Three national surveys on the physical status of 18-, 19-, and 20-year-old male candidates for military service were carried out in six geographic regions of China in 1955, 1974, and 2001. Data from these surveys for 72,000 individuals were compared by region, by time, and by age, and estimates of incremental changes by decade were made. Overall, at all time points, males in the north and northeast areas were larger and heavier than males in the southwest. Similarly, the proportion of males in the north and northeast who were overweight was greater than in the other areas. The proportion classified as "thin" was highest in the south, southwest, and northwest, reaching 42.6% in the northwest. When urban and rural areas were compared, the mean value of every measure in every region was higher for urban youth, with all but two comparisons reaching significance (P<0.05). Differences of chest circumference among age groups were significant, as were differences in height, weight, and body mass index for 18-year-olds compared to 20-year-olds. Overall, height increments per decade were greatest for males in the southwest (average of age groups 1.79 cm, 1974 to 2001) and least in the northeast (1.08), indicating some tendency toward convergence over time. Weight increments per decade over the same time were greatest in north China (1.37 kg) and least in the northwest region (0.58 kg).
The main objective of the work is to compare the growth and nutritional status of Australian Aboriginal term infants born with (n = 81) and without fetal growth restriction (n = 260). A prospective birth cohort study of 341 Aboriginal babies from the Top End of the Northern Territory of Australia was recruited at birth (1987-1990) and re-examined at a mean age of 18.3 years (2006-2008) for outcome measures of growth and nutrition status. Those with growth restriction at birth were 3 cm shorter (P = 0.0026) and 9 kg lighter (P = 0.0001) with head circumferences 0.95 cm smaller (P = 0.0008) than those without growth restriction. The proportions of growth restricted participants with body mass index <18.5 kg/m(2) were significantly greater (P = 0.028), and those with BMI > 25 kg/m(2) and with fat percentage >85th percentile were significantly smaller (P = 0.012 and 0.004, respectively). In this cohort, those Aboriginal babies born smaller and lighter have remained smaller and lighter at 18 years of age. However, the highest risk of later chronic noncommunicable disease has been reported in subjects who were born small and become relatively larger in later life. The continued study of this Aboriginal birth cohort will give us an opportunity to determine if and when in later life the effects of birth weight are modified by environmental nutritional factors.
Age-related patterns of body size and composition were studied in a cross-sectional sample of Japanese adults 18-59 years of age. Height, weight, the body mass index (BMI), body density (BD), percentage body fat (%Fat), fat mass (FM), fat-free mass (FFM), and the sum of seven skinfold thicknesses (SF) of 288 men and 552 women were considered. Body density was measured by underwater weighing densitometry. Mean values of height, weight, BMI, BD, %Fat, FM, FFM, and SF of males were 169.0 cm, 65.3 kg, 22.8 kg/m(2), 1.0600 g/ml, 17.0%, 11.4 kg, 53.9 kg, and 95.0 mm, respectively, while corresponding values for females were 157.4 cm, 52.9 kg, 21.4 kg/m(2), 1.0420 g/ml, 24.4%, 13.1 kg, 39.7 kg, and 128.2 mm, respectively. Height, BD, and FFM correlated negatively with age in both sexes, while weight, BMI, %Fat, FM, and SF correlated positively with age. The highest BD and the lowest %Fat were observed in males ages 20 to <25 years (G20) and in females 25 to <30 years (G25). The lowest BD and highest %Fat were observed in G50 in both sexes. Correlations among parameters of body size and composition were stable with age in each sex. Height correlated negatively with BMI and %Fat in females, but not in males. In males, FM started to increase between G20 and G25 and continued to increase until G50, while SF and BMI remained stable during this period. In females, FM accumulation started around 30 years of age and continued until G50 and was accompanied by increases in SF and BMI.
Family composition (e.g., the absence of a father) is associated with pubertal timing in women, although the socioendocrinology of the human primate is poorly understood. To better understand social influences on sexual maturation, retrospective data were collected on menarcheal age and family composition from a sample of approximately 1,938 participants from a college population. Absence of a biological father, the presence of half- and step-brothers, and living in an urban environment were associated with earlier menarche. The presence of sisters in the household while growing up, especially older sisters, was associated with delayed menarche. Menarcheal age was not affected by number of brothers in the household, nor was there an effect of birth order. Body weight and race were also associated with menarche. The present findings advance the literature as they are suggestive of putative human pheromones that modulate sexual maturation to promote gene survival and prevent inbreeding, as occurs in rodents and nonhuman primates.
Growth is a complex process, and only little is known on the genetic regulation of it. We analyzed the effect of genetic and environmental factors on growth in a longitudinal Swedish cohort of 231 monozygotic and 144 dizygotic twin pairs born 1973-1979 with length or height measured annually from birth to age 18. The data were analyzed by two different multivariate variance component models for twin data using the Mx statistical package. At birth and 1 year of age, a substantial part of the variation in length was because of common environment (50 and 57%, respectively) and the effect of genetic factors was minor. After 2 years of age, 91-97% of the variation of height could be explained by genetic differences whereas the rest was because of environmental variation not shared by twins. The genetic correlation between heights at ages 2 and 18 was 0.73 (95% confidence intervals 0.68-0.77) showing that 53% of the genes affecting height at these ages are the same or closely linked; with increasing age the correlation with genetic effects at age 18 become subsequently stronger. Especially in mid-childhood, growth was largely regulated by the same genetic factors. During puberty new genetic factors started to affect height, but also genetic variation affecting height at previous ages remained. These results suggest that genetic regulation of growth is rather uniform, which is encouraging for further efforts to identify genes affecting growth.
The purpose of this study was to examine differences of cardiorespiratory fitness (CRF) among weight groups, and the associations of CRF with obesity (body mass index) in a sample of young children. Anthropometric data (height, body mass, and two skinfolds) were collected for 255 healthy children aged 8-10 years (127 boys and 128 girls). Children were placed in three groups (nonobese, overweight, and obese), using body mass index (BMI) sex- and age-specific cutoff points. Cardiorespiratory fitness was assessed with a 1-mile run test. Participants were separated into two groups: fit and unfit, according to age- and sex-specific scores defined by FITNESSGRAM. The prevalence of overweight (30.5% vs. 29.1%) and obesity (13.2% vs. 12.6%) was at the same magnitude for boys and girls. Overall, 109 children (42.7%) were overweight and obese. Sums of skinfolds, weight, and BMI were significantly lower (P < 0.05) in lean boys and girls compared to their overweight and obese counterparts. Regarding height, no significant differences were found in girls, while in boys, significant differences were only found between nonobese and obese. No differences were found in obesity groups according to CRF in boys, while significant differences were found for girls (P < 0.01). Logistic regression analysis showed that girls who were overweight (odds ratio = 0.05, P = 0.000) or obese (odds ratio = 0.09, P = 0.001) were likely to be unfit. No significant results were found in boys. Overweight and obese children presented higher sums of skinfolds and weight compared with their lean counterparts. Increased BMI was significantly associated with lower CRF in girls. Thus, our data clearly showed potential gender differences of body composition in CRF, which would be of great clinical significance. Therefore, even at young ages, at least for girls, the beneficial impact of low BMI values on CRF is shown with important clinical and public health implications.
The trend in the body mass index (BMI) values of the US population has not been estimated accurately because the time series data are unavailable and the focus has been on calculating period effects.
To estimate the trend and rate of change of BMI values by birth cohorts stratified by gender and ethnicity born 1882-1986.
We use loess additive regression models to estimate age and trend effects of BMI values of US-born black and white adults measured between 1959 and 2006. We use all the National Health Examination Survey and National Health and Nutrition Examination Survey data.
The increase in BMI was already underway among the birth cohorts of the early 20th century. The rate of increase was fastest among black females; for the three other groups under consideration, the rates of increase were similar. The generally persistent upward trend was punctuated by upsurges, particularly after each of the two world wars. The estimated rate of change of BMI values increased by 71% among black females between the birth cohorts 1955 and those of 1965 is indicative of the rapid increases in their weight.
We infer that transition to postindustrial weights was a gradual process and began considerably earlier than hitherto supposed.
The phenomenon of kin-oriented help, according to inclusive fitness theory, should be of crucial importance with respect to the process of reproduction. This is due to the fact that the devoted time and resources might indirectly contribute to the reproductive performance of a donor. This study aimed at analyzing the kin effects on fertility in order to check whether help received from kinsmen enhance a recipient's reproduction in terms of parity transition risk, completed fertility, and the number of survivors. The data came from reconstitution of church registers from Bejsce parish, Poland. To estimate the kin effect, regression models for count outcomes and techniques of multilevel event history analysis were applied. The analyses have shown that completed fertility and parity-specific transition risks are strongly influenced by various kin groups. Moreover, a multilevel hazard model revealed differences in the patterns of the kin influence among controlled fertility than among natural fertility birth cohorts. Female reproductive outcome is influenced mainly by the presence of siblings and postreproductive helpers (grandparents). However, there is a negative impact of so-called helpers-at-the-nest (older children in the household) on parity transition risks.
The impact of the early loss of one's father or one's mother on the survival and age at death of children was investigated on the basis of a historical reconstitution of families from the Krummhörn (East Frisia/Ostfriesland; Germany) with the aid of Kaplan-Meier plots and the Cox regression. In our analyses, we took into account the changed situation of the family after the death of a parent by incorporating the surviving spouse's remarriage or relationships with stepparents. We find that the impact on survival of the children was sex-specific and also depended on whether and at what point in time during childhood their father or mother had died. As expected, children's immediate survival was strongly affected by maternal loss. A few results can be construed as survival diminishing long-term consequences of the early loss of a parent. Daughters who lost their fathers before their first birthday proved to have increased mortality over a longer period of their youth. The age at death of daughters was also lowered if they had to live with a step-mother during early childhood. To interpret these results, three hypotheses, including an (intrinsic) trade-off, compensation and a selection scenario, were tested. Other approaches, which are based, for example, on the extrinsic trade-off between mating effort and parental investment of the surviving parent, also appear to be suitable as an explanation for the long-term consequences, which eventually draws the conclusion that the compensation scenario is the most likely explanation for the consequences of early parental loss.
We describe the natal dispersal patterns of the Krummhörn population as the outcome of intrafamilial competition. Depending on the affiliation with a specific social group and the sex of the individual, this competition is driven by different factors and obeys a different functional logic: The dispersal patterns of the daughters of landless workers allow a mate competition scenario to be detected, whereas the dispersal behavior of the children of farmers (especially of the sons) is driven by a resource competition scenario.
We examine the height of non-Hispanic US-born children born 1942-2002 on the basis of all NHES and NHANES data sets available. We use the CDC 2000 reference values to convert height into height-for-age z-scores stratified by gender. We decompose deviations from the reference values into an age-effect and a secular trend effect and find that after an initial increase in the 1940s, heights experienced a downward cycle to reach their early 1950s peak again only c. 2 decades later. After the early 1970s, heights increased almost continuously until the present. Girls born in 2002 are estimated to be 0.35sigma and boys are 0.39sigma above their 1971 values implying an increase of approximately 2.5 cm between birth cohorts 1971 and 2002 as an average of all ages (Table 3). Age effects are also substantial-pointing to faster tempo of growth. Girls are c. 0.23sigma taller at age 11 and boys 0.15sigma taller at age 13 than reference values (Fig. 3). This translates into an age effect of approximately 1.7 and 1.3 cm, respectively. Hence, the combined estimated trend and age-effects are substantially larger than those reported hitherto. The 2-decade stagnation in heights and the upward trend beginning in the early 1970s confirm the upswing in adult heights born c. 1975-1983, and imply that adults are likely to continue to increase in height. We find the expected positive correlation between height and family income, but income does not affect the secular trend or the age effects markedly.
The city of Bahía Blanca occupies a strategic place in Argentina south of the Pampean region in the north-east corner of the Patagonia. Since 1828, this city has been the historical and political border between Amerindian lands in the south, and the lands of European colonists. Nowadays, Bahía Blanca is an urban population mainly composed by descendents of immigrants from Spain and other European countries with apparently low admixture with Amerindians. In view of the unexpectedly high Amerindian admixture levels (about 46.7%) suggested by mtDNA data, and protein markers (19.5%), we analyzed a set of 19 Alu polymorphisms (18 autosomal, 1 of Chromosome Y) in a well-documented genealogical sample from Bahía Blanca. The genotyped sample was made up of 119 unrelated healthy individuals whose birth place and grandparent origins were fully documented. According to available genealogical records, the total sample has been subdivided into two groups: Bahía Blanca Original (64 individuals with all 4 gandparents born in Argentina) and Bahía Blanca Mix (55 individuals with one to three grandparents born out of Argentina). Allele frequencies and gene diversity values in Bahía Blanca fit well into the European ranges. Population relationships have been tested for 8 Alu markers, whose variation has been described in several Amerindian and European samples. Reynolds genetic distances underline the significant genetic similarity of Bahía Blanca to Europeans (mean distance 0.044) and their differentiation from Amerindians (0.146). Interestingly enough, when the general sample is divided, Bahía Blanca Original appears slightly closer to Amerindians (0.127) in contrast to Bahía Blanca Mix (0.161). Furthermore, the genetic relationships depicted through a principal components analysis emphasize the relative similarity of Bahía Blanca Original to Amerindians. A thorough knowledge of the sample origins has allowed us to make a subtle distinction of the genetic composition of Bahía Blanca.
The records of height of 841,457 18-year-old Portuguese males were analyzed by area of residence (districts). The sample included all Portuguese 18-year-old males born between 1966 and 1979 and examined between 1985 and 1998, in the north, center, and south of Portugal. They represent all social strata. There were statistically significant differences (P < or = 0.001) among districts: males from Lisbon (172.8 cm) and Setúbal (172.7 cm), the most developed districts, were tallest, and those from Madeira (169.7 cm) and Coimbra (171.6 cm) were shortest. Compared with published data for 1904, there was a positive secular trend in height. The average increase was 8.93 cm and the estimated rate was 0.99 cm per decade. The changes that occurred were mainly the result of the reduction of the shortest classes of stature, those < 150 cm to 170 cm, and an increase in the frequency of the highest classes, > or = 170 cm. This positive trend and the changes in stature distribution must be related to the general improvement in standard living conditions that occurred in Portugal primarily after the 1960s and 1970s, especially in terms of nutrition and the health system. Taking into account the socioeconomic differences that still exist between districts, the results suggest that the secular trend in height should continue for the Portuguese population in future decades.
This study describes the mortality patterns during the present century (1914-1996) and investigates the epidemiological transition in a single community, Easter Island (Rapanui), the geographically most isolated inhabited island. Mortality patterns were reconstructed from civil records and included deaths of all island residents. The mean annual number of deaths is 9.3. A steady decline in the mortality rate linked to rapid modernization is the most relevant general trait. Although a small mortality crisis was detected in 9 years of the period studied, there was no significant seasonality in the deaths, possibly due to little climatic variation. The most serious sanitary problem was leprosy, endemic on the island from the end of the 19(th) century. Sanitary improvements, on one hand, and the effective breakdown of isolation, on the other, brought about the eradication of leprosy and the beginning of an epidemiological transition. In the latter years of the study, there was an increasing prevalence of degenerative diseases, connected, in part, with changes in the age structure of the population caused by the decline of mortality. A correspondence analysis shows the relationships between causes of death and age, and makes clear the different incidence of disease by age. The infant mortality rates were lower than in the Chilean population. Am. J. Hum. Biol. 12:371-381, 2000. Copyright 2000 Wiley-Liss, Inc.
Previous attempts to study the 1918-1919 flu in three small communities in central Manitoba have used both three-community population-based and single-community agent-based models. These studies identified critical factors influencing epidemic spread, but they also left important questions unanswered. The objective of this project was to design a more realistic agent-based model that would overcome limitations of earlier models and provide new insights into these outstanding questions.
The new model extends the previous agent-based model to three communities so that results can be compared to those from the population-based model. Sensitivity testing was conducted, and the new model was used to investigate the influence of seasonal settlement and mobility patterns, the geographic heterogeneity of the observed 1918-1919 epidemic in Manitoba, and other questions addressed previously.
Results confirm outcomes from the population-based model that suggest that (a) social organization and mobility strongly influence the timing and severity of epidemics and (b) the impact of the epidemic would have been greater if it had arrived in the summer rather than the winter. New insights from the model suggest that the observed heterogeneity among communities in epidemic impact was not unusual and would have been the expected outcome given settlement structure and levels of interaction among communities.
Application of an agent-based computer simulation has helped to better explain observed patterns of spread of the 1918-1919 flu epidemic in central Manitoba. Contrasts between agent-based and population-based models illustrate the advantages of agent-based models for the study of small populations.
Agent-based modeling provides a new approach to the study of virgin soil epidemics like the 1918 flu. In this bottom-up simulation approach, a landscape can be created and populated with a heterogeneous group of agents who move and interact in ways that more closely resemble human behavior than is usually seen in other modeling techniques. In this project, an agent-based model was constructed to simulate the spread of the 1918 influenza pandemic through the Norway House community in Manitoba, Canada. Archival, ethnographic, epidemiological, and biological information were used to aid in designing the structure of the model and to estimate values for model parameters. During the epidemic, Norway House was a Hudson's Bay Company post and a Swampy Cree-Métis settlement with an economy based on hunting, fishing, and the fur trade. The community followed a traditional, seasonal travel pattern of summer aggregation and winter dispersal. The model was used to examine how seasonal community structures and associated population movement patterns may have influenced disease transmission and epidemic spread. Simulations of the model clearly demonstrate that human behavior can significantly influence epidemic outcomes.
The present study is part of a large research project on growth, development, nutrition, and health of Caboclo populations from the Brazilian Amazon. The aim of this paper is to analyze the age of menarche in adolescents (N=164) and adult women (219) in the studied populations. Caboclo are admixed rural, peasant groups that live along the Amazon river and its tributaries, and there are few previous studies about them. Probit analysis of the status quo data yielded a median age at menarche of 12.29+/-1.76 years. The retrospective method was applied to recall data of the 77 post-menarcheal adolescents, yielding an average of 13.06+/-1.27 years. Number of children in the family did not show any statistical influence on age at menarche in any age group. In adult women, age at menarche decreased from 14.50 in those born in 1930 to 12.88 for those born in 1980 (F=4.371, P=0.001). The downward trend found was, on average, 0.237 year per decade in the study period. The median age at menarche in the adolescents (12.29 years) is one of the lowest values found for Central and South American populations. In the ecological context, a low age at menarche could be an adaptive advantage because it provides a greater chance for reproduction at a young age in an environment where, until recently, life expectancy was low. As has been reported for other developing countries, the change found in age at menarche in the women born from the 1930s to the 1980s is likely to be related to changes in health and nutritional factors that occurred in Brazil because this country experienced significant improvement in living standards related to education, vaccination, and health conditions, which, although not equally, reached all regions after the 1960s.
To investigate and replicate a multisystem model of biological risk, or allostatic load, in a sample of generally healthy older adults.
Multigroup confirmatory factor analysis (MG-CFA) was applied to data from the Lothian Birth Cohort 1936 (n = 726). Blood samples were taken at a physical examination. Three markers of inflammation (fibrinogen, interleukin-6, and C-reactive protein), five metabolic markers (high- and low-density lipoprotein, body mass index, glycated hemoglobin, and triglyceride), and blood pressure (mean sitting systolic and diastolic blood pressure) were used to estimate a second-order CFA model of allostatic load. Our sample was split into those taking antihypertensive, anti-inflammatory, lipid-lowering, and diabetes medications (n = 470), and those who were not (n = 256), in order to test the stability of the CFA model across groups.
In the nonmedicated sample, a second-order allostatic load model showed good fit to the data. However, the second-order model failed to estimate in the medicated group. The factor correlations between blood pressure and inflammation and metabolism were smaller in magnitude in the medicated group. Invariance analysis on the first-order measurement model suggested significant differences across groups in the associations of low-density lipoprotein and HbA1c with metabolism.
Reliable measurement of allostatic load is possible in ageing samples free of medications but is complicated in the presence of medications. MG-CFA represents a highly versatile method for the analysis of allostatic load. Am. J. Hum. Biol. 25:538–543, 2013.
This survey aimed at analyzing secular changes in the development of girls from Krakow, in the first decade of the 21st century, against the background of transformations observed in the previous century.
The data collected during a survey conducted in Krakow in 2010, in which the measurements of a total of 1,974 girls aged 3.5-18.5 years were taken, made a basis for this study. The results from the contemporary series were compared with previous surveys conducted in 1938, 1971, 1983, and 2000. The analysis of the survey made use of the results of body height and weight measurements, BMI, and the menarche, thelarche, and pubarche onsets determining the level of pubertal development. The development of secondary sex characters was assessed utilizing the criteria 5-stage scale established by Tanner. The mean age of the menarche onset and ages at beginning breast (B2) and pubic hair (PH2) development were calculated by means of the probit method.
In the physical development of girls a positive trend in body height changes in prepubescence and adolescence was still observed. The acceleration of body weight development in peripubescence is expressed by increased BMI. It is spectacular that body build gets slimmer at the age of 17 and 18, which is probably connected with conscious control of body weight, and pubertal acceleration is also maintained.
Still observed trends in morphological factors and pubertal acceleration require further monitoring out of concern for the health and proper development of children and adolescents.
Evidence shows a secular trend in physical growth in China in recent years. We analyze the secular trend of stature and body mass index (BMI) for the period 1950s-2005 to provide biological evidence for policy-makers to identify measures for improving Chinese children's health. Data come from the historical records in 1950s and the successive cycles of the Chinese National Survey on Student's Constitution and Health. Subjects were 7- to 18-year-old youth from 16 cities. Sex-age differences in mean stature and BMI values between the surveys were analyzed, and the increments per decade were compared. An overall positive secular trend was found in 1950s-2005. Mean stature of the 18-year olds increased from 166.6 to 173.4 cm for males and from 155.8 to 161.2 cm for females, yielding rates of 1.3 and 1.1 cm/decade; the overall increments of BMI values were 2.6 for males and 1.8 for females, yielding rates of 0.8 and 0.6/decade, respectively. The most significant changes occurred during puberty. The overall positive secular trend is closely associated with the socioeconomic progress and the improvement of livelihood. Strong evidence suggests that in China this trend will be continued for many years. Further studies are needed to explore how to ensure healthy changes for poorer rural youth. Effective preventive strategies and measures should be taken to prevent the progressive increase in the prevalence of childhood obesity accompanying this trend.