Stephen M. Bailey

Effect of parental fatness levels on the fatness of biological and adoptive children

As shown in pairings involving 2,845 biological children and 147 adopted children, fatness of the children increases in stepwise fashion according to parental fatness combinations (Lean X Lean through Obese X Obese) for both biological and for social (i.e., adopted) children as well, thus indicating that fatness (while strongly familial) is not necessarily genetic.

Genetics of Maturational Processes

The genetics of human maturational events, like the conventional genetics of dimensional development, has long been inferred from two different, quasi-experimental procedures. The first of these is the population comparison. The second of these involves family-line analysis. Together, under optimal conditions, they provide a partial indication of the extent to which specific maturational events differ in timing, between natural populations, on a primarily genetic basis.

The Symmetrical Nature of Bilateral Asymmetry (δ) of Deciduous and Permanent Teeth

Although there have been numerous studies of crown-size asymmetry and its implications. effectively beginning with BALLARD (Anglo Ortho 14: 67-70, 1944) it is not known whether left-right crown-size asymmetry (8) is symmetrically or asymmetrically distributed and therefore whether means, standard deviations and such measures as S2 (SUAREZ, Am J Phys Anthrop 41:411-416, 1974) are appropriate for evolutionary or developmental comparisons. Accordingly we calculated individual buccolingual asymmetry values (8) for 24 pairs of teeth (14 permanent and 10 deciduous) from 201 subjects, using optical scanner measurements from serial casts of each subject (VAN DER LINDEN ET AL, J Dent Res 51:1100, 1972). Then, percentiles for left-right asymmetry were computed as well as the mean, the standard deviation, and the third moment about the mean (V3). As shown in the table, left-right asymmetry values (8) for both deciduous and permanent teeth are in general sufficiently symmetrical for

Genetic and Nutritional Interactions

Differences in size, proportions, and body composition during growth and into adulthood result from interactions between the genetic material and the nutritional milieu, during both prenatal and postnatal development. So closely are nutrition and genetics related that one of these variables is often confounded with the other, and for many population differences the resolution is not yet fully clear.

Correction for Foreshortening in Optical Odontometry

Increasing use of optical odontometric techniques (cf. Biggerstaff, Angle Orthod., 40:28-36, 1970; Amer. J. Phys. Anthrop., 31:163, 1969; Corruccini, J. Dent. Res., 56:699, 1977; Van der Linden et al., J. Dent. Res., 51:1100, 1972) raises the question of to what degree measurements oriented to an optically foreshortened plane are comparable to those taken manually at the crown surface. We have investigated this problem using University of Michigan School Growth Study dental cast data, collected with the OPTOCOM (Van der Linden et al., ibid.). Measurements of 2397 molar and premolar mesial buccolingual cusp tip to cusp tip diameters, from 204 persons, were used. Because the OPTOCOM gives triaxial (X, Y and Z) coordinates, it was possible geometrically to reconstruct the differences between the foreshortened OPTOCOM measurements and conventional crown surface measurements of the same casts. The corrected diameter represents the hypotenuse of a right triangle completed by the mesial buccolingual cusp height differences and the horizontal (optical) plane. To validate use of the geometrically reconstructed surface planes as equivalent to the actual surface plane, measured with calipers, one of us (S. B.) measured a subsample of casts using both methods. Agreement between geometrically and manually measured surface planes was within one percent. When the optical plane diameters were compared to those from the geometrically reconstructed surface planes, for 2397 teeth, differences