Correlations between the cross-sectional area of the jaw muscles and craniofacial size and shape

In adult human subjects, the correlations were determined between the cross-sectional areas of the jaw muscles (measured in CT scans) and a number of facial angles and dimensions (measured from lateral radiographs). Multivariate statistical analysis of the skeletal variables in a group of 50 subjects led to the recognition of six independent factors determining facial shape, i.e., cranial base length, lower facial height, cranial base flexure and prognathism, facial width, mandibular length, and upper facial height. In 29 of these subjects, the cross-sectional areas of the jaw muscles were determined, and correlations between these areas and the scores on the above-mentioned factors were calculated. It appeared that the cross-sectional areas of temporalis and masseter muscles correlated positively with facial width, whereas the areas of masseter and both pterygoid muscles did so with mandibular length. It has been shown experimentally that a decrease in jaw muscle size in various animals likewise has an effect on facial width and mandibular length. Our results therefore support the hypothesis that in man too the jaw muscles affect facial growth and partly determine the final facial dimensions. They also hint that the role of each muscle is different.     

Family resemblance for neuromuscular performance in a Kansas Mennonite community

Familial phenotypic resemblance for six quantitative neuromuscular performance traits is analyzed by path analysis using data from the Mennonite community of Goessel, Kansas. Of the six traits only one, dominant hand strength, shows no evidence of parent-offspring transmission (t2 = 0.001) and only one, trunk flexibility, shows evidence of a high degree of transmissibility (t2 = 0.662). The four remaining traits display low to moderate levels of transmissibility (t2 = 0.073 to t2 = 0.245). A substantial residual sibling resemblance due to shared environmental effects is seen for all six traits. It is suggested that the high heritabilities found for many of these traits by other methods result from the inability of these methods to account for the shared nongenetic effects.     

Family resemblance for serum uric acid in a Jerusalem sample of families

Summary Familial aggregation of serum uric acid was studied in a sample of families examined in the Jerusalem Lipid Research Clinic. We first examined homogeneity of familial correlations across the major origin groups in the Israeli population sample. In general correlations were homogeneous across origin groups, except for spouse pairs. Pooled correlations among biological relatives across the origin groups were all statistically significant. Spouse correlation upon adjustment for concomitant variables was moderately positive (r=0.115), yet significantly different from zero. Genetic and cultural determinants of uric acid were estimated utilizing a path model with 10 parameters to be estimated from a total of 16 correlations. Under a reduced model, genetic heritability (h²) was estimated to be 0.47±0.05 and cultural heritability (c²) was 0.11±0.03. However, our data gave suggestive evidence that cultural heritability was higher in parents (c²=0.28) than in children (c²=0.10). Commingling analysis and segregation analysis were also performed, and our findings imply that in the Israeli population there is no evidence for a major gene for high uric acid levels segregating in families.     

Family resemblance for anthropometric traits II. Assessment of maternal occupational and age effects

The present study was based on a cross-sectional sample of 1326 subjects (197 fathers, 466 mothers, 307 sons and 356 daughters) belonging to 488 nuclear families from the province of Biscay (Basque Country, Spain), with the purpose of estimating the degree of familial resemblance, for several anthropometric traits, by analysing the correlation coefficients between parent-offspring pairs. Height, weight, biacromial and bicrystal breadths, humerus and femur biepicondylar breadths, arm, waist and hip circumferences, biceps, triceps, subscapular, suprailiac, abdominal, thigh and calf skinfolds were taken from each individual. BMI, WHR and the sum of the seven skinfolds was computed. The mother's occupation and the age of offspring were taken into account, since the combination of all these factors might have an effect on familial resemblance. The mothers were classified into housewife (HM) and working mothers (WM). The offspring were divided into prepuberal, puberal and postpuberal subgroups. Standardised residuals were used to compute father-offspring (FO) and mother-offspring (MO) relations through correlation coefficients computed by maximum likelihood. The results confirm the influence of age on the correlations, since FO correlations revealed an increasing trend in HM's children for weight and another six variables as they grew older. On the other hand, the weight change tends to decrease with age in FO correlations within the WM group. Depending on mother's occupation and children's age, the global trend in the sample results in higher correlations in the second group (WM) than in the first one (HM) for the whole age range, but specially in FO correlations before puberty, where four variables (weight, bicrystal breadth, triceps and subscapular skinfolds) yield statistically significant differences.     

Family resemblance for glucose tolerance in a Melanesian population, the Tolai

Path analysis of family resemblance for plasma glucose concentration, 2 h after an oral glucose challenge, failed to detect significant genetic heritability. There were no intergenerational differences and marital resemblance was moderate. Over one-third of sibling environmental similarity was due to non-inherited factors. Cultural inheritance was very strong, tending to mimic genetic inheritance, and cultural heritability was considerable. Measures of obesity were included in the environmental index, an estimate of familial environment, in this analysis, for comparability with previous studies. Since obesity appears, in part, to be a heritable trait, in future studies a bivariate approach to family resemblance for both glucose tolerance and obesity could yield important additional insight.     

Family resemblance for cranio-facial measurements in Velanti Brahmins from Andhra Pradesh, India

Maximum likelihood estimates of familial correlations are presented for 12 cranio-facial measurements taken on 399 nuclear families from Southern India. Marital resemblance is significantly different from zero for head circumference, head breadth, minimum frontal breadth, bizygomatic breadth, total facial height, and nasal height, but not for bigonial breadth, nose breadth, nose depth, or ear dimensions. All other familial correlations are significantly greater than zero except for the father-daughter correlation for nasal depth. Path analysis with a TAU transmission model with sex effects reveals that family resemblance for head circumference, head length, bigonial breadth, total facial height, and nasal height, but not for bigonial breadth, nose breadth, nose depth, or ear dimensions. All other familial correlations are significantly greater than zero except for the father-daughter correlation for nasal depth. Path analysis with a TAU transmission model with sex effects breadth, and sex effects in transmission were found for head breadth and nose dimensions. Sex effects in this sample may be due to the fact that different anthropometrists were used for male and female subjects.     

Visualizing patterns of craniofacial shape variation in Homo sapiens

The geometric morphometric analysis of shape variation in complex biological structures such as the human skull poses a number of specific challenges: the registration of homologous morphologies, the treatment of bilateral symmetry, the graphical representation of form variability in three dimensions and the interpretation of the results in terms of differential growth processes. To visualize complex patterns of shape change, we propose an alternative to classical Cartesian deformation grids in the style of D'Arcy W. Thompson. Reference to the surface structures of the organism under investigation permits a comprehensive visual grasp of shape change and its tentative interpretation in terms of differential growth. The application of this method to the analysis of human craniofacial shape variation reveals distinct modes of growth and development of the neurocranial and viscerocranial regions of the skull. Our data further indicate that variations in the orientation of the viscerocranium relative to the neurocranium impinge on the shapes of the face and the cranial vault.     

Some remarks on the interpretation of Penrose's size and shape components. Craniometrical similarities of African groups

The present paper deals with cranial data of different African races and shows how far the components “size” and “shape” of the Penrose distance express biological distances as well as the kind of changes occurring when different groups of variables are used. The stability of the distances between the populations was further studied by exchanging the reference group on a racial and subracial level. The analyses supply a differentiated picture according to the affinities, especially between the reference populations of the major races. Europoid and Negroid populations can often be separated only by shape distance, while the size distance is more suitable for separating Bushmen and Hottentots.     

Family configuration and family size

Abstract

In a sample of 61,829 families, the probability of having an additional child is higher in those families with all children of the same sex as compared to those families with children of both sexes. In addition, families with only boys were more likely to have an additional child than families with all girls.     

Family configuration and family size

In a sample of 61,829 US families, the probability of having an additional child is higher in those families with all the children the same sex as compared to those families with children of both sexes. Data are from families of American high school students who took the National Merit Scholarship Qualifying test in 1965. All families with 3 or 4 children were selected. Families with only boys were more likely to have an additional child than families with all girls. Less than 1% of the variance in family size is explained by family configuration. Although the sample size makes these results unequivocal for the population involved, the population is clearly biased in favor of white middle class families.     

On the use of size functions for shape analysis

According to a recent mathematical theory a shape can be represented by size functions, which convey information on both the topological and metric properties of the viewed shape. In this paper the relevance of the theory of size functions to visual perception is investigated. An algorithm for the computation of the size functions is presented, and many theoretical properties of the theory are demonstrated on real images. It is shown that the representation of shape in terms of size functions (1) can be tailored to suit the invariance of the problem at hand and (2) is stable against small qualitative and quantitative changes of the viewed shape. A distance between size functions is used as a measure of similarity between the representations of two different shapes. The results obtained indicate that size functions are likely to be very useful for object recognition. In particular, they seem to be well suited for the recognition of natural and articulated objects.     

Environmental and sibling resemblance components of variance and covariance in traits of early child development

The multiple regression analyses were undertaken to elucidate the significance and relative importance of different potential determinants of several child development traits (i.e. age at which child 1. turns himself over; 2. sits up; 3. stands up; 4. walks, and 5. cuts his first tooth). Despite the fact that we used a relatively wide gamut of potential determinants (such as parental age, geographic origin, occupation, current residence, or family size) of trait variability, the results of multiple regression analysis (N = 300 families) indicate an almost complete absence of significant factors and studied variables of development. Sibling resemblance component of variance and covariance for five mentioned traits of development and some morphological characters (weight, length and head circumference at day of birth and at 16 months) were studied in 66 families. The transmissibility ("heritability") values for the development traits were small, ranging from 0 ("Turn") to 0.42 ("Walked"). The Findings suggest that there are significant inverse relationship between some of the developmental traits and inborn morphological characters.     

Family resemblance for anthropometric and blood pressure measurements in Black Caribs and Creoles from St. Vincent Island

This paper examines family resemblance for five anthropometric measurements (height, weight, triceps skinfold, upper arm circumference relaxed [UACR] and flexed [UACF] and for systolic and diastolic blood pressure in a group of adult Caribbean islanders of primarily African ancestry. Six hypotheses about family resemblance are tested by using path analysis and likelihood ratios. Significant intergenerational transmission is found only for height and UACR. For weight, UACF, and diastolic blood pressure, non-transmissible sibling resemblance is the primary component of family resemblance, although significant marital resemblance exists for diastolic blood pressure. Triceps skinfold and systolic blood pressure show no evidence of any family resemblance. Although results for highly heritable traits such as height are comparable to reports from other populations, measurements with a large contribution from common family environment or residual environmental effects, such as triceps skinfold or blood pressure, have much lower family resemblance in this population than in other populations. We hypothesize that this difference is due to the fact that adult children and their parents do not share a common household in this culture and to the presence of major nonfamilial environmental factors contributing to obesity and hypertension in this population.