Sexual Differences, Fluctuating Asymmetry and Their Implications in the Growth Rate and Developmental Stability of the Permanent Dentition and the Primary Dermal Ridge of the Fingers and Palms

This study presents evidence that specific genetic material influences the growth rate and developmental stability of two genetic systems, dermal ridges and permanent dentition, having mutually exclusive developmental periods. Dermal ridges develop rapidly early in fetal life, while the permanent dentition develops slowly in a postnatal environment. Theories centering on the nature and effects of the specific genetic material (heterochromatin) are discussed and applied whenever possible.

The data for this investigation were collected from students in introductory anthropology classes at the University of Tennessee, Knoxville. The sample consists of fifty males and fifty females. Finger prints, palm prints and casts of the permanent dentition were obtained from each subject. In addition, each subject filled out a questionnaire eliciting genetic and dental information.

Statistical analysis of the data was carried out utilizing the Statistical Package for the Social Sciences (SPSS). Summary statistics, Pearson product-moment correlation coefficients and canonical correlations were calculated for all dental and dermal variables. Fluctuating asymmetry was used as a measure of developmental stability. The degree of fluctuating asymmetry was determined by taking the absolute right-left difference for each variable, and by calculating the correlation coefficient between sides. Canonical correlation analysis was used to evaluate the degree to which dermal and dental systems are integrated.

The results indicate that there are sexual differences in size and shape of the teeth, ridge counts, fluctuating asymmetry and the degree to which the two systems are integrated. The most significant finding is that the dental and dermal systems are integrated. This may be due to the nature of the genetic material responsible for them, or because they develop and grow under similar controlling factors. Although the findings suggest that there is some common control throughout prenatal and postnatal development, they do not supply evidence as to their specific nature.