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PubMed1986

Competition and body size.

If being larger than competing conspecifics is important for fitness, then an unstable escalation of body size may result. In asexual populations, a cycling of sizes can occur but for sexual diploids, an irreversible size increase is more likely. Several factors can produce a stable distribution of sizes, but a single body size or even a narrow range of sizes cannot be stable. For example, enough environmental variance can produce stability without any genetic variability in the population. Or, with no environmental variance, a high cost of fighting between similar sizes or, for diploids, an increasing mortality with size may lead to a stable distribution of sizes. A game theory model is used to investigate the existence and form of a stable distribution of body sizes in a population.

Animals↗
PubMed2001

Does body size account for gender differences in femur bone density and geometry?

The extent to which greater bone strength in men is caused by proportionately greater bone mass versus bigger bone size is not clear, primarily because the larger overall body size of men has made direct comparisons of skeletal measures difficult. We examined gender differences in femur neck (FN) areal bone mineral density (BMD) values collected from 5,623 non-Hispanic whites aged 20+ years in the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994) before and after correction for measured height and weight. We supplemented the conventional areal BMD data (Hologic QDR 1000) with measurements of areal BMD and geometric properties (subperiosteal width, section modulus, and cortical thickness) made at narrow "cross-sectional" regions traversing the FN and the proximal shaft using a structural analysis program. Before body size adjustment, men had significantly higher values than women for all variables at the three measurement sites (p < 0.0001). Adjustment for body size reduced the differences between the sexes for all variables but had a greater effect on BMD (1-8% higher in men) than on geometry (5-17% higher in men). When examined by age, the sex discrepancy was significantly greater in the older group for all variables except subperiosteal widths. We conclude that although body size difference may account for most of the areal BMD difference between men and women, male bones are still bigger in ways that suggest greater bone strength. These differences may contribute importantly to lower fracture risk in men.

Absorptiometry, Photon↗
PubMed2007

Do age- and sex-related variations reliably reflect body size in non-human primate vocalizations? A review.

In vocal communication, the mechanisms of sound production are well understood. The length of the vocal folds determines the minimum fundamental frequency, while the size and the shape of the vocal tract affect its filtering characteristics and hence, the resonant frequencies. Both measures-vocal fold length and vocal tract length-are related to body size and therefore, acoustic features are expected to vary with body size. Because direct measures of body size are difficult to obtain from free-ranging animals, age and sex have often been used as proxies. We surveyed studies which included direct measures of size or weight, and also studies in which only age and/or sex differences were examined. The main purpose was to examine whether age- and sex-related variations in acoustic features meet the predictions generated from our knowledge about sound production. Our survey revealed that compared to smaller animals, larger animals utter longer calls, with a lower fundamental frequency, with smaller formant dispersion, and with the energy concentrated in lower frequencies. Age and sex reliably reflect the influence of body size on acoustic features when gross size differences are examined. However, within age- and sex classes, this relationship may break down. In addition to body size, other factors such as internal state or social context may also influence the structure of vocal signals and highlight the richness of information in calls that is potentially available to listeners.

Aging↗
PubMed2000

Components of lifetime mating success and body size in males of a scrambling damselfly.

Sexual selection is hypothesized to favour small body size in males of scrambling species, that is, those in which males obtain matings by actively searching for females. I tested this hypothesis in a natural population of the scrambling emerald damselfly, Lestes sponsa. Mating efficiency (matings/visit to the pond) was the most important factor explaining variation in male lifetime mating success (LMS; 71%). This suggests a large potential for sexual selection. Path analysis of male LMS suggested a quality factor that positively affected both mating efficiency and life span. In contrast with the small-male mating advantage hypothesis, part of this potential for sexual selection was realized as stabilizing selection on male body size, indicating that there may also be a lower limit to body size for mating efficiency. This also illustrates that the constancy of body size may be explained by sexual selection alone. Survival explained about 20% of the variation in LMS and random processes were potentially important for determining LMS. My results show the problems of using mating efficiency as a measure for the intensity of sexual selection and the need to distinguish between potential and realized selection pressures, especially when comparing the importance of natural and sexual selection. I discuss mechanisms that may have caused the intermediate-male mating advantage in this scrambling species. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2001

Ability of young women to recall past body size and age at menarche.

OBJECTIVE: The ability of young women (n = 132, average age 17 years) to recall body size and age at menarche was examined. The use of body silhouettes to assist women in recalling their body size at menarche and to represent their current body size was also evaluated. RESEARCH METHODS AND PROCEDURES: Subjects, who previously participated in a cohort study, were asked to recall height and weight at the time of menarche, to select body silhouettes that best reflected their body shape at the time of menarche and their current body shape, and to recall age at menarche. Two sets of body silhouettes were developed, one representative of an adult body shape and another representative of an adolescent body shape. RESULTS: Pearson correlation coefficients between the adult and adolescent body figures and actual body mass index (BMI; kg/m(2)) at the time of menarche were not significantly different (r = 0.82 for adult figures vs. r = 0.72 for adolescent figures, p > 0.05). The correlation between actual BMI at the time of menarche and body silhouette (r = 0.77, all subjects) was similar to the correlation between actual and recalled BMI at the time of menarche (r = 0.83) as well as the correlation between current BMI and current body silhouette (r = 0.75). Recalled and actual ages at menarche were highly correlated (r = 0.83). DISCUSSION: The recall of body shape was considered to be a less precise measure of body size than asking about height and weight, but use of body silhouettes may offer advantages in certain situations.

Adolescent↗
PubMed1998

Effects of Predator-prey Body Size Ratios on the Stability of Food Chains.

The effects of predator-prey body size ratios on the resilience and probability of stability in linear Lotka-Volterra food chains have been analysed. The prey per capita interaction strengths of the model is assumed to be negatively correlated to the relative size difference between a predator and its prey. The relationship between prey interaction strength and predator-prey body size ratios is motivated by energetical arguments. Analytical results show that, given this assumption (on prey interaction strengths) and if average (relative) size differences between predators and their prey decrease with the trophic position of the consumer (as found in a large number of "real food webs") the probability of local stability in model food chains is increased (when compared to model chains with a constant predator-prey body size ratio). Numerical simulations show that in most cases, the effect on the probability of stability is accompanied by an increase in resilience. For example, as model food chain length is increased from two to three trophic levels in one simulation, the return time increases by more than two orders of magnitude with a constant predator-prey body mass ratio while chains longer than four are not feasible. With a decreasing predator-prey body mass ratio on the other hand, the return time does not increase as rapidly and feasible equilibria exist for longer chains. The relationship between resilience and food chain length is, in this model, affected by the relationship between the predator-prey body mass ratio and the trophic position of the predator, that is, how fast this ratio decreases with increasing trophic height. The effect of body mass on consumer mortality rates, and subsequently on the probability of stability and resilience is also analysed. Decreasing mortality rates with increasing body size does not change the results qualitatively, it only increases the probability that an equilibrium is feasible.Copyright 1998 Academic Press

Journal Article↗
PubMed1999

Correlated responses to selection on body size in Drosophila melanogaster.

Correlated responses to artificial selection on body size in Drosophila melanogaster were investigated, to determine how the changes in size were produced during development. Selection for increased thorax length was associated with an increase in larval development time, an extended growth period, no change in growth rate, and an increased critical larval weight for pupariation. Selection for reduced thorax length was associated with reduced growth rate, no change in duration of larval development and a reduced critical larval weight for pupariation. In both lines selected for thorax length and lines selected for wing area, total body size changed in the same direction as the artificially selected trait. In large selection lines of both types, the increase in size was achieved almost entirely by an increase in cell number, while in the small lines the decrease in size was achieved predominantly by reduced cell size, and also by a reduction in cell number. The implications of the results for evolutionary-genetic change in body size in nature are discussed.

Animals↗
PubMed2003

Growth in bone strength, body size, and muscle size in a juvenile longitudinal sample.

A longitudinal sample of 20 subjects, measured an average of 34 to 35 times each at approximately 6-month intervals from near birth through late adolescence, was used to investigate relationships between body size, muscle size, and bone structural development. The section modulus, an index of bone strength, was calculated from humeral and femoral diaphyseal breadth measurements obtained from serial radiographs. Muscle breadths of the forearm and thigh, also measured radiographically, were used to estimate muscle cross-sectional areas. Body size was assessed as the product of body weight and bone length (humeral or femoral). Stature was also investigated as a surrogate body size measure. Growth velocity in femoral strength was strongly correlated with growth velocity in body weight. femoral length (r2=0.65-0.80), very poorly correlated with growth velocity in stature (r2<0.06), and weakly but significantly correlated with growth velocity in thigh muscle size (r2=0.10-.25). Growth velocity in humeral strength was moderately correlated with that for body weight x humeral length (r2=0.40-0.73), very poorly correlated with that for stature (r2<0.05), and showed a marked sex difference with forearm muscle area velocity, with males having a stronger correlation (r2 approximately 0.65) and females a much weaker correlation (r2 approximately 0.15). Ages at peak adolescent growth velocity were nonsignificantly different between bone strength, body weight x bone length, and muscle area, but significantly earlier for stature. Thus, while there was an early adolescent "lag" between stature and bone strength, there was no such "lag" between a more mechanically appropriate measure of body size and bone strength. "Infancy peaks" in bone strength velocities, earlier in the humerus than in the femur and not paralleled by similar changes in body size, may be the result of the initiation of walking, when mechanical loads relative to body size are changing in both the upper and lower limbs. These results argue strongly for the importance of mechanical factors in the development of the preadult skeleton. Body size is the most important element in the weight-bearing lower limb skeleton, while both body size and muscle strength are important in the upper limb, especially in males.

Adolescent↗
PubMed2005

Modeling physiological and anthropometric variables known to vary with body size and other confounding variables.

This review explores the most appropriate methods of identifying population differences in physiological and anthropometric variables known to differ with body size and other confounding variables. We shall provide an overview of such problems from a historical point of view. We shall then give some guidelines as to the choice of body-size covariates as well as other confounding variables, and show how these might be incorporated into the model, depending on the physiological dependent variable and the nature of the population being studied. We shall also recommend appropriate goodness-of-fit statistics that will enable researchers to confirm the most appropriate choice of model, including, for example, how to compare proportional allometric models with the equivalent linear or additive polynomial models. We shall also discuss alternative body-size scaling variables (height, fat-free mass, body surface area, and projected area of skeletal bone), and whether empirical vs. theoretical scaling methodologies should be reported. We shall offer some cautionary advice (limitations) when interpreting the parameters obtained when fitting proportional power function or allometric models, due to the fact that human physiques are not geometrically similar to each other. In conclusion, a variety of different models will be identified to describe physiological and anthropometric variables known to vary with body size and other confounding variables. These include simple ratio standards (e.g., per body mass ratios), linear and additive polynomial models, and proportional allometric or power function models. Proportional allometric models are shown to be superior to either simple ratio standards or linear and additive polynomial models for a variety of different reasons. These include: 1) providing biologically interpretable models that yield sensible estimates within and beyond the range of data; and 2) providing a superior fit based on the Akaike information criterion (AIC), Bayes information criterion (BIC), or maximum log-likelihood criteria (resulting in a smaller error variance). As such, these models will also: 3) naturally lead to a more powerful analysis-of-covariance test of significance, which will 4) subsequently lead to more correct conclusions when investigating population (epidemiological) or experimental differences in physiological and anthropometric variables known to vary with body size.

Anthropometry↗
PubMed1984

The relation of adiposity and body size to chronological age in olive baboons.

Mixed-longitudinal data on adiposity and body size were taken on 250 male and 452 female olive baboons aged between birth and 8 years. Adiposity was measured as skinfold thickness at the neck, subscapular, suprailiac, and triceps sites; body size measures included weight, crown-rump length, and triceps circumference. Males and females were treated independently and compared for gender differences. Data were tabulated to examine the relation of the somatometric variables to age and the patterns of association among the variables. Females averaged larger skinfold values at all sites for most ages. Males were significantly heavier, longer, and exhibited greater triceps girth at all ages except birth and 1 year where no significant gender difference was found for crown-rump length. In general the three measures of body size were significantly correlated at all ages as were the four measures of adiposity. Significant associations between adiposity and body size measures were not consistent among various ages.

Aging↗
PubMed1989

The impact of maternal uterine genotype on postnatal growth and adult body size in mice.

Embryo transfers were used to demonstrate that the genotype of the mother providing the uterine developmental environment significantly influences postnatal growth and adult body size of her progeny. Irrespective of their own genotype, mouse embryos transferred into the uterus of an inbred strain with large body size (C3H) had greater body weights, longer tails and higher growth rates than those transferred into the uterus of a strain with small body size (SWR). Uterine heterosis on body size was smaller than progeny heterosis, and both progeny and uterine heterosis persisted in adult mice. Uterine litter size was significantly negatively associated with body weight, tail length, growth rate and the timing of developmental events. The inbred SWR strain was more sensitive to the embryo transfer procedure than the C3H strain, but effects due to embryo transfer were moderate. Prenatal uterine effects have ramifications for biotechnologies utilizing embryo transfer as well as predictions about evolutionary change by selection.

Analysis of Variance↗
PubMedDate not supplied

Blood pressure, electrolytes, and body size: their relationships in young relatives of men with essential hypertension.

In 154 white chldren aged 8 to 18 years from four large kindreds, relationships among blood pressure (BP), age, sex, body size, and electrolyte excretion were studied. Each kindred was ascertained through one male aged 35-58 years with essential hypertension, namely, a diastolic blood pressure (DBP) over 95 mm Hg. Weight, relative weight (relative to NCHS median for age, sex, and stature), subcutaneous fatfolds, various indices of obesity, and other measures of body size were significantly correlated with systolic blood pressure (SBP) and DBP in each sex (r = 0.3 to 0.7). Sodium and potassium excretion in 24-hour urine was also positively correlated with some measures of body size, and tended to increase with body size at a slightly more rapid rate in boys than in girls. In addition, there was a strong correlation between electrolyte excretion and BP in boys (r = 0.2 to 0.6); however, when the effects of age, body size and fatness were statistically removed, the correlations between BP and electrolyte excretion were not significant, except for 4th phase diastolic pressure (DBP4). These data, therefore, while not strongly supporting a relationship between sodium excretion and BP in children, do not rule out such a relationship, especially in families with a history of hypertension. In addition, these data provide further evidence of a very strong association between BP and body size and fatness in boys and girls.

Adolescent↗
PubMed1997

The influence of methodological differences on the outcome of body size estimation studies in anorexia nervosa.

A major problem that has dogged research into body image disturbance in anorexia nervosa concerns the diversity of measurement procedures employed in studies of body size estimation. Many researchers believe that results obtained with different procedures cannot meaningfully be compared with each other, because the methods used measure different aspects of the body image. A meta-analysis of 33 body size estimation studies was conducted to investigate whether methodological differences do indeed influence outcome. This analysis revealed a general overestimation of body size among anorexia patients. Although a difference in mean effect size was found between studies using Body Part and Whole Body methods, this difference was absent when only the most commonly used Body Part method, the visual size estimation procedure, was considered. Among Whole Body methods, silhouette methods could not be distinguished from the rest in terms of effect size. It was concluded that Whole Body methods and the visual size estimation procedure assess correlated aspects of the body image.

Adolescent↗
PubMed1998

Hormone replacement therapy and body size: how much does lifestyle explain?

OBJECTIVE: Our purpose was to assess the association of hormone replacement therapy with body size. STUDY DESIGN: A total of 1658 randomly selected women aged 45 to 64 years in four regions (two provinces in eastern Finland, one southwestern province, and the capital area) were studied in a 1992 population survey. Linear regression analysis was used to assess the use of hormone replacement therapy as a determinant of body size, measured with the body mass index, the waist/hip ratio, and the body fat percentage and adjusted by sociodemographic (area and education) and lifestyle (diet, smoking, physical activity, and alcohol use) factors. The regression coefficients of hormone replacement therapy use obtained from the model when including sociodemographic and lifestyle variables (beta 1a[Hormone replacement therapy use] = -0.98) were compared with the coefficients obtained when these variables were excluded (beta 1b[Hormone replacement therapy use] = -1.36). The percentage of change (beta 1b-beta 1a/beta 1b%) in the regression coefficients denoted the variability explained by sociodemographic and lifestyle characteristics. RESULTS: Hormone replacement therapy users (28%, n = 463) had higher education, were more often from the capital area, had a significantly higher healthy diet factor score, and were leaner than nonusers. Use of hormone replacement therapy remained a significant determinant of body mass index, waist/hip ratio, and body fat percentage after adjusting for sociodemographic and lifestyle factors. Of the difference in body mass index between hormone replacement therapy users and non-users, 28% were explained by lifestyle and sociodemographic risk factors, respectively, 31% of the difference by use of the waist/hip ratio and 42% by use of the body fat percentage. CONCLUSIONS: The difference in body size between hormone replacement users and nonusers may not be the result of self-selection. The use of hormone replacement therapy was inversely associated with body size in menopause.

Body Composition↗
PubMed2003

Correlated evolution of colour pattern and body size in polymorphic pygmy grasshoppers, Tetrix undulata.

Theory posits that selection on functionally interrelated characters will promote physical and genetic integration resulting in evolution of favourable trait-value combinations. The pygmy grasshopper Tetrix undulata (Orthoptera: Tetrigidae) displays a genetically encoded polymorphism for colour pattern. Colour morphs differ in several traits, including behaviours, thermal biology and body size. To examine if these size differences may reflect phenotypic plasticity of growth and development in response to temperature we used a split brood-design and reared hatchlings from mothers belonging to different morphs in different thermal environments (warm or cold) until maturity. We found that time to maturity was longer in the cold compared with the warm treatment. In the warm (but not in the cold) treatment time to maturity also varied among individuals born to mothers belonging to different colour morphs. Although low temperature and long development time are normally accompanied by increased body size in ectotherms, our results revealed no difference in size at maturity between individuals reared in the two temperature treatments. There was also an increase (not a decrease) in adult body size with shortened time to maturity across families within each treatment. Taken together, this suggests that body size is canalized against environmental perturbations, and that early maturation does not necessarily trade off against a size-mediated decrease in fecundity. Heritability of body size was moderate in magnitude. Moreover, body size at maturity varied among individuals belonging to different morphs and was influenced also by maternal colour morph, suggesting that a genetic correlation exists between colour pattern and body size. These findings suggest that different characters have evolved in concert and that the various colour morphs represent different evolutionary strategies, i.e., alternative peaks in a multi-modal adaptive landscape.

Adaptation, Physiological↗
PubMed2006

Perceived body size and desire for thinness of young Japanese women: a population-based survey.

The present study describes findings in relation to perceived body size and 'desire for thinness' by age and residential areas ('metropolitan areas', 'large cities', 'small cities' and 'towns') among young Japanese women. Data on 1731 non-pregnant, non-lactating women aged 15-39 years from the 1998 National Nutrition Survey of Japan were used. Current body size was evaluated by BMI percentiles (lean, <5th; underweight, 5th or = BMI <25th; normal, 25th< or = BMI< 75th; overweight, 75th < or =BMI <95th; obese, > or =95th), calculated for 5-year age groups. Perceived body size was obtained by self-report. We defined 'overestimation' as non-overweight, non-obese women who perceived themselves as being 'overweight' or 'obese'. Desired body size was evaluated by applying the desired BMI to these cut-off points. Of all the women, 48.4% perceived themselves as being 'overweight' or 'obese', and 43.7% desired a 'lean' or 'underweight' body size. Adjusted for the current BMI, the OR for 'overestimation' calculated by a logistic regression model was significantly elevated in the 15-19-year age group (OR 2.79; 95% CI 1.76, 4.43), compared with the 25-29-year age group. The OR for 'desire for thinness' was significantly high in the 35-39-year age group (OR 2.74; 95% CI 1.93, 3.89) and the 15-19-year age group (OR 2.26; 95% CI 1.57, 3.24). Women living in metropolitan areas had higher OR for 'desire for thinness' (but not for 'overestimation') than did women in towns (OR 1.47; 95% CI 1.05, 2.07). The findings suggest the nature of excessive weight concerns of young women in Japan; thus efforts to control such health-risk behaviours at a national level are urgent.

Adolescent↗
PubMedDate not supplied

Successive resetting of the set point for target body size.

Previous studies support the existence of a central set point for target body size. The set point is a hypothetical fixed reference for body size. The present experiments were carried out to determine whether target body size and, by implication, the putative set point can be consecutively reset or whether, once set by an extraneous factor, it is refractory to another extraneous factor. Male and female rats were given 6.0 Gy whole head X-irradiation at two days of age or were sham-irradiated as controls. Significant permanent reduction of body weight, tibia length, and pituitary weight resulted from head-irradiation in both males and females; gonad weight was reduced in males but not significantly in females. At 41 days of age the irradiated animals were injected sc with cortisone acetate, 1 mg/25 g body weight/day, or saline. During cortisone treatment the head-irradiated rats had a decrease in body weight velocity; the effect was greater in males than in females. Following treatment growth velocity approached normal in treated males, and slightly exceeded normal in treated females. Treated males had significantly reduced body weight, tail length, and tibia length at the end of the study. Treated females showed a similar pattern of body weight growth to the treated males, but there was not a significant long term reduction of body weight or change in tail length or tibia length. Final pituitary and gonad size was not affected by cortisone treatment in either sex. The results indicate that the reset of target size after head-irradiation does not result from damage to putative control.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1996

Age and sex differences in body size and composition during rhesus monkey adulthood.

Body size and composition were measured in forty-one adult Rhesus monkeys (Macaca mulatta) in order to characterize changes that occur during later life for both genders. Data were obtained by traditional somatometric techniques and by dual-energy X-ray absorptiometry. Representative monkeys were chosen within six categories defined by age (Young Adult, 6-9 year-old; Middle Aged, 15-19 year-old; Older Adult, 26-30 year-old), and sex. Body weight and most external measures of body size were greater during middle age and later life than in young adulthood, as were body fat content and lean body mass. Females tended to have a higher percentage body fat than males in all age categories. Lean tissue mass was markedly greater in the two younger groups for both sexes, compared to older adults. Bone mineral content and density were higher in the males than the females, but differences in bone mineralization among age groups did not achieve statistical significance. Such data derived from adult nonhuman primates are useful for defining fundamental biological changes with age in these species, and have value as a comparative model for studies of human aging and age-related morbidity.

Adipose Tissue↗