Showing papers in "American Journal of Human Biology in 1999"

Discontinuity of life conditions at the transition from the Roman imperial age to the early middle ages: Example from central Italy evaluated by pathological dento-alveolar lesions.

Abstract: Teeth are highly informative in the study of past human populations. In particular, the occurrence of lesions in the masticatory apparatus relates diseases, diet, and living conditions. The dental pathology of three skeletal samples from the north-central part of Latium (central Italy) is reported. Two of them belong to the Roman Imperial Age (1st-3rd century AD): the first (including 942 permanent teeth and 1,085 tooth sockets) represents the rural town of Lucus Feroniae and is mainly composed of slaves and/or war veterans, whereas the second (872 permanent teeth and 1,325 tooth sockets) comes from the Isola Sacra necropolis at Portus Romae and represents the "middle class" segment of an urban population. The medieval sample (912 teeth and 1,097 tooth sockets), dated to the 7th century AD, belongs to the Lombard necropolis of La Selvicciola. All of the samples were examined for caries, abscesses, antemortem tooth loss, calculus, alveolar resorption, attrition, and enamel hypoplasia; standard methods were used to identify, classify, and quantify these conditions. The results reveal different patterns of dental and alveolar lesions for the three populations, indicating a different combination of dietary factors and hygienic conditions in the Roman samples compared to the Lombard series. As evidenced by multivariate correspondece analysis, the Romans show afffinites between each other, whereas the Medieval sample appears associated with the incidence of caries and the pathological conditions related to them, thus indicating increase of these lesions and deterioration of the quality of life in the transition to the early Middle Ages. These data agree with the respective archeological characterizations of the necropolises and the hypothetical social composition of each population. Am. J. Hum. Biol. 11:327-341. Copyright 1999 Wiley-Liss, Inc.

Role of exercise intervention in improving body fat distribution and risk profile in children

Abstract: The influence of 4 months of physical training (PT) and detraining on body composition, and risk factors for coronary artery disease (CAD) and noninsulin-dependent diabetes mellitus (NIDDM) was examined. The subjects were 81 obese 7-11-year-olds. At baseline, visceral adipose tissue (VAT) was the main adiposity variable cross-sectionally associated with unfavorable levels of the lipid-lipoprotein risk factors, while fat mass was more highly correlated with insulin, systolic blood pressure, and leptin. Adiposity measures were associated with unfavorable concentrations of clotting-fibrinolysis factors. Subjects were randomly assigned to engage in PT for the first or second 4-month period of the study; for most variables, tests were done at 0, 4, and 8-month time points. The PT program was offered 5 days a week for 40 min/session. For the 73 children who completed 4 months of PT, attendance was 80% and heart rate during the sessions was 157 bpm. PT had a favorable influence on percent fat, VAT, subcutaneous abdominal adipose tissue, insulin, triacylglycerol, and cardiac parasympathetic activity. Detraining generally led to unfavorable changes in percent fat and associated risk factors. Leptin decreased during periods of PT and increased following cessation of PT. No significant changes due to PT were found for diet, hemodynamic, left ventricular, or most lipid parameters. Thus, 4 months of controlled PT, without dietary intervention, had a favorable impact on body composition and some obesity-associated CAD/NIDDM risk factors. Am. J. Hum. Biol. 11:237-247, 1999. Copyright 1999 Wiley-Liss, Inc.

Hormonal changes during puberty and their relationship to fat distribution.

Abstract: In adults, abdominal visceral adiposity is related to an increased risk of cardiovascular diseases, Type 2 diabetes mellitus, and stroke. The antecedents of these conditions likely begin with the alterations in body fat distribution during childhood and adolescence. The sexually dimorphic alterations in fat distribution are influenced by sex differences in hormone concentrations, anatomical differences in the number and density of specific hormone receptors, capillary blood flow, and the activity of enzymes promoting lipid synthesis or degradation. Hormones influencing the amount and regional distribution of adipose tissue during puberty include cortisol, insulin, growth hormone, and the sex steroids. Cortisol and insulin promote fat deposition while the sex steroids and GH stimulate lipolysis. An overly sensitive hypothalamic-pituitary-adrenal axis may exist in obesity and disrupt the balance between the lipogenic effects of cortisol and insulin and the lipolytic effects of sex steroids and growth hormone. Leptin is released from the adipocytes and may act as a metabolic signal to the hypothalamic areas controlling satiety, energy expenditure, and the regulation of cortisol, insulin, sex steroid and growth hormone release. The complex issues of the hormonal control of alterations in body fat distribution during puberty are developed and a working model is proposed. Am. J. Hum. Biol. 11:209-224, 1999. Copyright 1999 Wiley-Liss, Inc.

African-derived South American populations: A history of symmetrical and asymmetrical matings according to sex revealed by bi- and uni-parental genetic markers.

Abstract: Estimates of African, European, and Amerindian contribu- tions to the gene pool of 11 predominantly African-derived South American populations were obtained using five autosomal and one Y chromosome hy- pervariable loci, as well as mitochondrial DNA (sequences of the first hyper- variable segment of the control region, plus two restriction sites and the presence or absence of the CoII/tRNA Lys intergenic 9-bp deletion). The three latter characteristics are reported here for the first time for 42 individuals living in three Brazilian populations. Thirty-eight sequences were identified in these persons; 17 (45%) could be classified as being of African, 4 (11%) of Amerindian, and 2 (5%) of European origin. Evidence for asymmetrical mat- ings in relation to sex and ethnic group was obtained for nine of the 11 populations. The most consistent finding was the introduction of European genes through males, but the results differ in the several communities, in- dicating the importance of local factors in such interactions. Am. J. Hum. Biol. 11:551-563, 1999. © 1999 Wiley-Liss, Inc.

Critical appraisal of the estimation of body composition via two-, three-, and four-compartment models.

Abstract: This review explores the robustness of the assumptions underpinning the two- (fat mass [FM], fat-free mass [FFM]), three- (FM; total body water [TBW], fat free dry solid), and four- (FM; TBW; bone mineral [BM], residual) compartment models of body composition. The measurement of body density (BD) via underwater weighing (UWW) and TBW via isotopic dilution are the two most frequently used two-compartment techniques. The former assumes that the FM and FFM have densities of 0.9007 g/cm(3) and 1.1000 g/cm(3), respectively, while the latter uses a FFM hydration constant. Although both techniques can estimate body composition precisely (technical error of measurement [TEM]: UWW = 0.4 %BF; TBW = 0.6 %BF), the validity of these estimates is adversely affected by biological variability in the assumed percentages for the FFM components (TBW = 73.72%; protein = 19.41%; BM = 5.63%; non-BM = 1.24%). The three-compartment model, which incorporates measures of BD and TBW, greatly increases validity by removing errors relating to variability in TBW, which comprises the largest percentage of the FFM and is furthermore acutely variable. The four-compartment model marginally improves on the three-compartment model by additionally controlling for BM, which displays less variability than the TBW component of the FFM. The three- and four-compartment models therefore provide more valid estimates of body composition than the two-compartment model, and this increased accuracy is not offset by propagation of errors (TEM = 0.7 %BF for both models) from the combinations of multiple measurements (BD, TBW, BM). Am. J. Hum. Biol. 11:175-185, 1999. Copyright 1999 Wiley-Liss, Inc.

Effect of developmental and ancestral high altitude exposure on chest morphology and pulmonary function in Andean and European/North American natives.

Abstract: Chest depth, chest width, forced vital capacity (FVC), and forced expiratory volume (FEV1) were measured in 170 adult males differing by ancestral (genetic) and developmental exposure to high altitude (HA). A complete migrant study design was used to study HA natives (Aymara/Quechua ancestry, n = 88) and low altitude (LA) natives (European/North American ancestry, n = 82) at both altitude (La Paz, Bolivia, 3,600 m) and near sea level (Santa Cruz, Bolivia, 420 m). HAN and LAN migrant groups were classified as: N(th) generation migrants, born and raised in a non-native environment; child migrants who migrated during the period of growth and maturation (0-18 yrs); and adult migrants who migrated after 18 years of age. Chest depth, FVC, and FEV1 measures were larger with increasing developmental exposure in both HAN migrants at LA and LAN migrants at HA. Developmental responses were similar between HAN and LAN groups. FVC and FEV1 measures were larger in HANs vs LANs born and raised at HA to suggest a genetic effect, but were similar in HANs and LANs born and raised at LA. The similarity of HAN and LAN groups at LA suggests that the genetic potential for larger lung volumes at HA depends upon developmental exposure to HA. Additional data for females (HANs at HA, n = 20, and LAN adult migrants to HA, n = 17) show similar differences as those shown between male HAN and LAN groups. Am. J. Hum. Biol. 11:383-395, 1999. Copyright 1999 Wiley-Liss, Inc.

Human body composition: A review of adult dissection data

Abstract: Although body composition analysis is popular, dissection data are sparse and sometimes difficult to access. Published data that include the weights of skin, adipose tissue, muscle, and bone, along with body weight, are reviewed. The 31 men and 20 women include 34 cadavers from three separate dissection studies in Brussels, 12 from 19th century reports, and 5 from the United States. The age range was 16-94y. Men differed from women in that they had less adipose tissue and more muscle in both absolute and relative terms. The body mass index (BMI) did not differ between the sexes, because lower weights of muscle and bone compensated for the greater adiposity in women. The relationship between the BMI and relative adiposity was significant, but the BMI explained only about one-third of the variance in adiposity, indicating that in this sample it is a poor predictor of fatness. The composition of the fat-free weight (FFW) and adipose tissue free weight (ATFW), though less variable than body weight, showed enough variability that the assumption of constancy of the fat-free body required for densitometry and other indirect methods of fat estimation, could not be supported. In the few dissections that did fat extraction, essential on non-adipose fat, varied from 4-14% of the FFW, thus undermining the concept of lean body weight. More dissection data are needed, especially in children and adolescents, and especially in conjunction with in vivo body composition methods to help in their validation. Am. J. Hum. Biol. 11:167-174, 1999. Copyright 1999 Wiley-Liss, Inc.

Effect of DHA-containing formula on growth of preterm infants to 59 weeks postmenstrual age.

Abstract: Between May 1993, and September 1994, a randomized, blinded clinical trial was conducted to evaluate measures of growth and body composition in 63 (32 males; 31 females) healthy, low-birth-weight infants (940-2250 g) who were randomly assigned to an infant formula with docosahexaenoic acid (22:6n3, DHA, 0.2 wt%) from fish oil or to a control formula. A preterm formula with or without DHA was fed beginning at 7-10 days prior to hospital discharge through 43 weeks postmenstrual age (PMA). Then, from 43-59 weeks PMA, infants were fed a term infant formula with or without a corresponding amount of DHA. Growth (weight, length, head circumference), regional body fatness (triceps, subscapular, suprailiac skinfold thicknesses), circumferences (arm, abdominal, chest), and estimates of body composition determined by total body electrical conductivity (TOBEC) (fat-free mass [FFM]) were evaluated. Growth was slower in males fed the DHA formula. They had significantly (P < 0.05) smaller gains in weight, length, and head circumference between study enrollment to 59 weeks PMA than those fed the control formula. At 51 weeks PMA, males in the DHA group had significantly smaller head circumferences (P < 0.05) and lower FFM (P < 0.05). At 59 weeks PMA, males in the DHA group weighed less (P < 0.05), had shorter recumbent lengths (P < 0.01), smaller head circumferences (P < 0.05), and lower FFM (P < 0.01) than those fed the control formula. Energy intakes from formula (kcal/d), however, were lower at 51 weeks (P < 0.05) and 59 weeks (P < 0.05) PMA in males fed the DHA formula. Adjusted for body weight (kcal/kg/d), mean energy intakes from formula at 51 and 59 weeks PMA were not significantly different between feeding groups. The differences in recumbent length, head circumference, and FFM remained statistically significant after controlling for energy and protein intakes (P < 0.01). For all males, neither FFM nor total body fat (TBF), when expressed as a percentage of total body weight, differed significantly between feeding groups. Among females, there were no significant differences between the feeding groups in measures of growth, body composition, or energy intake. The results indicated that infant formula with fish oil containing DHA and EPA in a 5:1 ratio had a significant, negative effect on growth and body composition in males during the first 6 months of life. It is not clear why the growth deficits were limited to males and not females. The eicosanoids, bioactive metabolites of omega-3 and omega-6 fatty acids, may mediate several important growth hormones. The present results do not support the addition of DHA alone in infant formulas. Am. J. Hum. Biol. 11:457-467, 1999. Copyright 1999 Wiley-Liss, Inc.

Increased tooth crown size in females with twin brothers: Evidence for hormonal diffusion between human twins in utero.

Abstract: In rodents, the position of a fetus in utero is associated with the expression of sexually dimorphic traits. This phenomenon has been explained by prenatal diffusion of sex hormones among litter mates. To test for such effects in humans, female-male twin pairs provide a natural experiment. The size of dental crowns is a sexually dimorphic trait which can be measured with a high degree of reliability. Thus, two crown diameters of 28 permanent teeth were recorded for 56 opposite-sexed (OS) and 242 same-sexed (SS) twin pairs, and 150 singletons. Comparisons of OS twins with SS twins and singletons within each sex reveal that OS females have consistently larger teeth (on average) than other females, while there is no consistent difference between OS and SS twin males. It is proposed that diffusion of sex hormones from male to female co-twins in utero may account for the increased tooth size in OS females. This study is one of the first to report such an effect on a morphological variable in humans. The finding that the maxillary canine, one of the most sexually dimorphic teeth, exhibits the least effect in OS female twins, suggests that prenatal sex hormone levels may have less impact on sexual dimorphism in the maxillary canines than in other permanent teeth. Am. J. Hum. Biol. 11:577-586, 1999. Copyright 1999 Wiley-Liss, Inc.

Visceral fat in prepubertal children: Influence of obesity, anthropometry, ethnicity, gender, diet, and growth.

Abstract: Visceral fat, or intra-abdominal adipose tissue (IAAT) lies deep within the abdominal cavity and can only be directly quantified with imaging techniques. IAAT has been detected in children as young as 5 years of age. IAAT generally increases in proportion with general fatness, but the relationship between IAAT and total body fat is complex; in children, a major portion of the variance in IAAT is independent of total body fat. The waist-to-hip ratio and the trunk:extremity skinfold ratio are not good indices of IAAT in children, and central skinfolds and waist circumference alone are highly correlated with IAAT as well as subcutaneous abdominal adipose tissue (r = 0.85-0.92). African-American children have less IAAT than Caucasian children, and gender differences in IAAT become more apparent after adolescence. Preliminary evidence in children suggests that IAAT may have a stronger influence on cardiovascular risk factors than dietary fat intake. Preliminary evidence in children also suggests that acquisition of IAAT during growth is a linear process that occurs in proportion to general increases in body fat. The study of the regulation of IAAT acquisition during childhood development and its relationship with long-term disease risk is in its early infancy and further studies are required. Am. J. Hum. Biol. 11:201-207, 1999. Copyright 1999 Wiley-Liss, Inc.

Variation in Subcutaneous Adipose Tissue Distribution Associated With Age, Sex, and Maturation

Abstract: Age-, sex-, and maturity-associated variation in subcutaneous adipose tissue (SAT) distribution is reviewed and then considered longitudinally in a sample of Polish youth. Current study of adipose tissue distribution places considerable emphasis on abdominal adiposity, specifically intra-abdominal or visceral adipose tissue (VAT). Most studies of children and adolescents do not include an abdominal skinfold, and when it is available, the skinfold is grouped with others as a sum of skinfolds. Correlations between abdominal VAT and SAT based on computerized tomography in non-obese children are moderate to high, and those between the suprailiac and abdominal skinfolds and abdominal VAT are moderately high. Changes in three individual skinfolds (triceps, subscapular, abdominal) and ratios of the skinfolds were considered by chronological age and relative to the timing of peak height velocity (PHV), and in children of contrasting maturity status in participants of the Wroclaw Growth Study, 193 boys and 197 girls, who were followed longitudinally from 8 to 18 years of age. Individual skinfolds behave differently during childhood and adolescence, and the changes are influenced by the timing of the adolescent growth spurt. Sex differences in estimated velocities are negligible up to about 2 years before PHV; then velocities tend to be higher in girls. The velocity of the triceps skinfold is negative in boys just before and after PHV; estimated velocities for the trunk skinfolds are positive through the growth spurt in both sexes, and are somewhat greater after PHV, especially in girls. The individuality of changes in individual skinfolds during the adolescent spurt contributes to changes in the relative distribution of SAT at this time. The timing of the adolescent growth spurt is an important factor influencing the distribution of SAT both in the total sample and in youth classified as early and late maturing. Am. J. Hum. Biol. 11:189-200, 1999. Copyright 1999 Wiley-Liss, Inc.

Evolutionary process and the ecology of human immune function.

Abstract: Evolutionary principles inform central design features of hu- man immune defenses and provide key insights into this complicated host defense system. This article explores the selection pressures and adaptive responses that have elaborated the immune system over the course of evo- lution and discusses their implications for understanding contemporary im- mune development and function. Special attention is given to the challenges posed by diverse, rapidly evolving pathogens and the mammalian response to these challenges. The process of lymphocyte diversity generation and subse- quent clonal selection is quintessentially Darwinian: pathogens provide se- lection pressure that drives differential replication of host immune cell lines, resulting in changes in genetic frequencies within an individual's population of lymphocytes. The immune system also incorporates nongenetic transgen- erational processes in the transfer of antibodies from mother to offspring through the placenta and breast milk. The consequences of these observa- tions for human development, health, and the ecology of immune function are considered throughout the life cycle. Specifically, evolutionary processes pro- vide insight into autoimmunity, thymic function, lymphocyte development, infectious disease risk, and lactation. While much work in evolutionary medi- cine focuses on the discordance between evolved biology and rapidly changing cultural environments, with respect to the immune system, evolutionary pro- cesses may be most revealing when applied within individuals. Am. J. Hum. Biol. 11:705-717, 1999. © 1999 Wiley-Liss, Inc.

Syndrome X in children: Influence of ethnicity and visceral fat.

Abstract: Syndrome X, the clustering of risk factors for cardiovascular disease, is recognized as an obesity-related health concern among adults. In particular, individuals with visceral (intra-abdominal) obesity are prone to developing syndrome X. Although extremes of visceral fat have been detected in prepubertal children, the extent to which visceral fat contributes to the development of disease risk factors in children is not known. This review addresses the occurrence of syndrome X and its antecedents in the pediatric population, as well as two specific issues regarding syndrome X in children: the roles of ethnicity and visceral fat. The central feature to emerge from most studies is that basal and post-challenge insulin are significantly higher in African-American, Mexican-American, and Pima Indian children compared to Caucasian children. Although these ethnic differences are independent of adiposity, adiposity is associated with greater insulin in all ethnic groups examined. Mexican-Americans have a higher lipid risk factor level, which is related to greater obesity, and African-Americans have lesser lipid-associated risk, independent of obesity. African-American children may be more likely to develop type 2 diabetes due to obesity-independent hyperinsulinemia and insulin resistance, but appear less predisposed to the obesity-related clustering of risk factors associated with syndrome X. Mexican-American children may be more likely to develop syndrome X due to greater obesity-related hyperinsulinemia and dyslipidemia. Total body fat, rather than visceral fat, appears be the primary determinant of insulin resistance prior to puberty. However, visceral adipose tissue is uniquely related to both insulin and lipid risk factors in children and adolescents, and thus may contribute to the development of the early stages of syndrome X. Am. J. Hum. Biol. 11:249-257, 1999. Copyright 1999 Wiley-Liss, Inc.

Culture, skin color, and arterial blood pressure in Brazil.

Abstract: Populations of African descent in North and South America have higher mean blood pressures and higher rates of hypertension than populations of European descent or populations in Africa. Within populations of African descent, darker skinned persons have higher blood pressures than lighter skinned persons. Whether examined within or between populations, there is an interaction between skin color and socioeconomic status (SES) in relation to blood pressure, with persons with dark skin color and low SES having the highest blood pressures. This interaction was examined in Brazil using a measure of a cultural dimension of SES called "cultural consonance in lifestyle." This measure was derived using cultural consensus analysis linked with social survey data. It was found that darker skinned Brazilians with lower cultural consonance in lifestyle had adjusted systolic blood pressures 16.2 mm Hg higher than darker skinned Brazilians with higher cultural consonance (P <.01); the corresponding difference in adjusted diastolic blood pressure was 9.7 mm Hg (P <.04). The differences for lighter skinned Brazilians were 6.4 mm Hg (P <.02) and 1.0 mm Hg (not significant), respectively. These results could be due either to an interaction of genetic predisposition and SES, or the result of a socially and culturally-mediated process. Given that cultural consonance in lifestyle measures the ability of the person to live up to cultural norms, and given the existence of racial stratification in Brazil, it is argued that a social and cultural mediation of the relationship is more plausible. Am. J. Hum. Biol. 11:49-59, 1999. Copyright 1999 Wiley-Liss, Inc.

Relationship between abdominal visceral fat and metabolic risk factors in obese adolescents

Abstract: The distribution of body fat may play an important role in determining the risk of obesity-related morbidity in obese adults. In view of the alarming increase in adolescent obesity, this article addresses whether defects in insulin action and secretion and increased intra-abdominal fat that typify central obesity in adults are expressed early in the course of developing obesity. The euglycemic hyperinsulinemic clamp technique with stable isotopes was used to determine insulin effects on glucose and glycerol turnover in obese and lean adolescents. The hyperglycemic clamp was used to quantitate insulin secretion, while magnetic resonance imaging was used to directly assess abdominal subcutaneous and visceral fat. The results indicate that obese adolescent girls have the following characteristics: 1) insulin resistance with major defects in oxidative and nonoxidative glucose metabolism; 2) hyperinsulinemia in the fasting state and in response to intravenous glucose; and 3) impaired suppression of total body lipid oxidation and plasma FFA concentrations in response to insulin. Am. J. Hum. Biol. 11:259-266, 1999. Copyright 1999 Wiley-Liss, Inc.

An approach to estimating bone and joint loads and muscle strength in living subjects and skeletal remains.

Abstract: Skeletal physiology that clarified after 1990 shows that bone modeling normally makes a bone strong enough to keep its loads from causing strains above a "modeling threshold". That arrangement adapts bone strength to the largest loads on a bone, which are usually brief and infrequent. Accordingly, in bone adapted chiefly to uniaxial compression loads, the modeling threshold's value and the cross-sectional amount of that bone could suggest the size of those loads. Bone loaded in that way does support the articular surfaces of synovial joints as their "supporting bone", so its amount could suggest the size of the loads it had adapted to, and therefore the loads on the joint that it supports. During growth a joint's size is proportional, directly but not linearly, to the size of its total loads, so that its size at skeletal maturity could be an index of those loads at that time. Joints cannot decrease in size. Yet throughout life their supporting bone can decrease or increase in strength and "mass" to adapt to changes in a joint's loads. Thus, an adult joint's size could suggest the size of the loads it adapted to by skeletal maturity, while the cross-sectional amount of its supporting bone at any later age could reveal the size of those loads at that later age, and thus suggest any change in those loads that might have occurred after skeletal maturity. Since the bone modeling threshold, and the relationships between bone strain, stress, and unit loads are now known, it is possible with this procedure to estimate the total loads on joints, and how body weight and muscle strength contribute to those loads in both living subjects and skeletal remains. To make a reliable technology of the idea involves some problems which this paper identifies and suggests how to resolve. Am. J. Hum. Biol. 11:437-455, 1999. Copyright 1999 Wiley-Liss, Inc.

Genetics of abdominal visceral fat levels

Abstract: The purpose of this review is to explore the evidence accumulated thus far that suggests a genetic component to the observed variation in abdominal visceral fat (AVF) levels. The precise determination of AVF levels in humans is limited to methods such as computerized tomography and magnetic resonance imaging; thus, few studies have examined the role of genetic factors on this phenotype. Evidence from the Quebec Family Study (QFS) and the HERITAGE Family Study indicates that between 50-55% of the variance in AVF levels, adjusted for total fatness, is attributable to genetic factors. Additionally, a major gene hypothesis for AVF was supported in the both the QFS and HERITAGE Family Study. However, after adjustment for total fat mass the support for a major gene was reduced, suggesting that a major gene which affects fat mass may also affect AVF either directly (pleiotropy), or indirectly. The search for candidate genes that may impact AVF levels is in its infancy, and few candidate genes have been identified. However, the glucocorticoid receptor (GRL), ss3 adrenergic receptor (ADRB3), and fatty acid binding protein 2 (FABP2) genes have been significantly associated with AVF or intra-abdominal fat levels in humans. In addition, three quantitative trait loci obtained from crosses of mice, the Do2, Mob4, and Qbw1 loci have been linked with mesenteric or abdominal fat and are thus considered positional candidate genes for AVF levels. The search for candidate genes or random genetic markers associated with AVF levels is a challenging prospect. However, given the significant heritability of this phenotype, the quest remains promising. Am. J. Hum. Biol. 11:225-235, 1999. Copyright 1999 Wiley-Liss, Inc.

Porters of the eastern hills of Nepal: Body size and load weight

Abstract: This study documents the activities of 635 porters transporting goods along three traditional trade routes of eastern Nepal. Nearly 95% of the porters were male. They ranged in age from 10-65 years, and most of them had begun to perform long-distance portage at 12-15 years of age. Mean body mass and height of adult males in the combined sample (n = 438) was 49.7 +/- 5.0 kg and 155.5 +/- 6.5 cm, respectively. Adult males age 20-49 years carried loads of 73 +/- 15 kg, equivalent to 146% +/- 30% of body mass. Body size of adult males was not a strong predictor of load weight. The correlation between body mass and load was r = 0.24 (P < 0.0001), and between height and load was r = 0.16 (P < 0.001). Another significant determinant of load weight was whether the load was carried for profit or for domestic use. The most reasonable explanation for the ability of Nepali porters to carry such large loads in spite of their small body size is the ability to pace themselves by making frequent rest stops. Heart rate monitoring of 26 adult male commercial porters demonstrated how porters regulate heart rate and energy expenditure by resting the load every two to three minutes on the T-headed walking stick (tokma) and by setting the load periodically on load-resting platforms (chautaras) for longer recovery periods. Am. J. Hum. Biol. 11:1-11, 1999. Copyright 1999 Wiley-Liss, Inc.

Enamel hypoplasia in a Canadian historic sample.

Abstract: Analyses of historical skeletal samples provide useful comparisons of the prevalence of skeletal indicators of stress to documentary information on health, diet, and socioeconomic status. A sample of the permanent dentitions of 253 adults from the St. Thomas' Anglican Church 19th-century skeletal sample in Belleville, Ontario, was examined macroscopically for the prevalence of enamel defects on the six anterior maxillary and mandibular teeth. The maximum frequency of hypoplasias on the left mandibular canine is 36.1%. The prevalence of enamel defects is low to moderate compared to almost all other reported frequencies in historical samples, which is consistent with historical descriptions of this developing community of middle to high socioeconomic status Canadians. Hypoplasias are significantly more frequent in males but there are no significant differences in the mean age at death between individuals with hypoplasia and those without. Calculations of the peak ages of occurrence of hypoplasias fall within the commonly observed 2-4-year range. This is not consistent with separate studies, demographic, isotopic and historical, of the introduction of complementary foods to 19th-century Belleville infants and of the weaning process. These results do not support the view that peak ages of occurrence of hypoplastic defects are associated with the cessation of breast-feeding or the weaning process in general. Am. J. Hum. Biol. 11:513-524, 1999. Copyright 1999 Wiley-Liss, Inc.

Weight, stature, and body mass index data for Mexican Americans from the third national health and nutrition examination survey (NHANES III, 1988-1994).

Abstract: Selected age- and sex-specific percentiles are presented for 4,054 Mexican American children ages 1-18 years who were included in the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994). These percentile values are compared with corresponding percentiles for Mexican Americans from the Hispanic Health and Nutrition Examination Survey (HHANES, 1982-1984). In each sex, the weight and weight/stature(2) percentiles from NHANES III were significantly larger than those from HHANES. For weight, the NHANES III values tended to be clearly larger after 11 years in males and females, and they were larger for weight/stature(2) at the 50th and 90th percentiles in each sex after 6 years. For stature, the NHANES III values were significantly larger at the 90th percentile among females, but the differences were not significant for any other percentiles among females or males. In comparison with non-Hispanic White children, Mexican American children tend to be shorter and heavier, especially after the preschool period. The similarity of the findings for stature from NHANES III and HHANES indicates that the shorter statures of Mexican Americans are not cohort-specific. The tendency to larger values for weight/stature(2) in Mexican Americans has important public heath implications since this ratio tends to track after early childhood, and high ratios in adulthood constitute an important risk factor for common diseases such as diabetes mellitus and coronary heart disease. Am. J. Hum. Biol. 11:673-686, 1999. Copyright 1999 Wiley-Liss, Inc.

Blood pressures of Sherpa men in modernizing Nepal.

Abstract: The relationship among potential risk factors (diet, adiposity, physical activity levels (PALs), and age) for elevated blood pressures (BP) was examined in 253 Sherpa men living in Kathmandu (low altitude sample: LAS) and in the Khumbu (high altitude sample: HAS) regions of Nepal. The study is based on data collected to assess nutritional status. Elevated BPs were highly prevalent among both samples of men (LAS: 21.7% and HAS: 24.8%). The highest percentage of elevated BP was found among the urban HAS (32.4%), while rural HAS had the lowest percentage (16.1%). Stepwise regression analyses showed that the BMI, age, and alcohol consumption were strong predictors of systolic blood pressure (SBP), and the BMI and age were strong predictors of diastolic blood pressure (DBP). No correlations were found among BP and intakes of sodium, calcium, potassium, or fat when all men (normotensive and elevated BP) were examined. Bivariate association between the BMI and BP showed that obese men were 8.6-9.1 times more likely to have elevated BP, and that alcohol consumers were 2.6 times more likely to have elevated BP. The results suggest that elevated BP is a problem for a large portion of male Sherpas and appears to be associated with an elevated BMI. A survey of the region only 30 years ago showed no cases of hypertension. Increasing adiposity, due primarily to decreasing PALS, places this population at risk of chronic illness in the future. Am. J. Hum. Biol. 11:469-479, 1999. Copyright 1999 Wiley-Liss, Inc.

History of the study of human body composition: A brief review.

Abstract: This review assembles a chronology of human body composition research with the goal of exposing historical roots and identifying future potential trends. Body composition research has emerged over the past several decades as a distinct field, and for many scientists body composition is their primary investigative focus. Technological advances will likely move the field forward and, ultimately, help to expand knowledge of human body composition variability in health and disease. Am. J. Hum. Biol. 11:157-165, 1999. Copyright 1999 Wiley-Liss, Inc.

Gastrointestinal parasitic infection, anthropometrics, nutritional status, and physical work capacity in Colombian boys

Abstract: This article tests the hypothesis that the presence of gastro- intestinal parasites in Colombian boys is negatively associated with anthro- pometric characteristics, physical work capacity, blood hemoglobin (Hb) lev- els, and nutritional status. Anthropometric, Hb, V. O2 max, and parasite load data were collected on 1,016 boys in Cali, Colombia. The boys were classified as lower socioeconomic class (SEC) from either urban or rural environments, and upper SEC from an urban environment. Sixty-three percent of the boys were infected with gastrointestinal parasites and, of the infected boys, 80- 95% had light parasite loads. Parasites found included Necator americanus, Ascaris lumbricoides, Entamoeba histolytica, Trichuris trichiura, Giardia spp., and Enterobius vermicularis. Infected boys had significantly lower weight, stature, weight-for-height (among 6-9-year-old boys), Hb levels, and V. O2 max (ANCOVA, controlling for age and SEC). In terms of nutritional status, infected boys were 1.47 times more likely to be classified as iron deficient than noninfected boys (chi-square, P < 0.001), and 1.61 times more likely to be classified as stunted (P < 0.001). Infection was not associated with wasting in any SEC group. In conclusion, light to moderate gastrointestinal parasite loads were associated with significantly lower weight, stature, weight-for-height (in 6-9-year-old boys), Hb levels, and V. O2 max, and a sig- nificantly higher frequency of IDA and stunting. These data suggest that comprehensive analyses of the nutritional status of populations in regions endemic for parasitic infection should include testing for the presence of infection. Am. J. Hum. Biol. 11:763-771, 1999. © 1999 Wiley-Liss, Inc.

Modeling the effects of nutritional and socioeconomic factors on the growth and morbidity of Kenyan school children.

Abstract: This paper estimates dynamic models for the height, head circumference, weight, and morbidity of approximately 110 Kenyan school children (6-9 years) in a multivariate longitudinal data framework Dynamic models allow anthropometric dimensions to depend on the respective measurements in the previous period The system of 4 equations specified for height, head circumference, weight, and morbidity incorporates the inter-relationships among these variables; explanatory variables in the model consist of nutritional, socioeconomic, demographic, and environmental factors The model parameters are estimated using the principle of maximum-likelihood, while controlling for the unobserved between-children differences The main findings are, first, that calcium intakes are positively associated with height while protein and energy intakes are associated with weight Vitamin A intakes are negatively associated with morbidity Second, socioeconomic status plus the cash income of the household is a significant predictor of height, head circumference, and morbidity Third, maternal height is positively associated with children's height and maternal body mass index (BMI) is positively associated with children's weight Fourth, parents' scores on psychological tests, mother's age, and children's hemoglobin concentration are negatively associated with morbidity while mothers' morbidity is positively associated with children's morbidity Implications of the modeling results are discussed Am J Hum Biol 11:317-326, 1999 Copyright 1999 Wiley-Liss, Inc