Osteometrical Study of Genetic and Environmental Influences on the Shape of the Human Skeleton: I. Intra-familiar Resemblances in the Skeletal Morphology of the KANASEKI-Family and Other Familial Series

Abstract

It is well known that the osteometric traits are determined by both genetic and environmental factors. Therefore, in the analysis of anthropological characters, we must take into account the differences in the contributions of genetic and of environmental factors. However, the lack of suitable skeletal series of individuals with known family relationships makes the study of heritability very difficult.
The late Dr. Takeo KANASEKI (1897-1983), who proposed "hybridization theory" as to the origin of the Japanese by osteometrical analysis, realized the necessity of familial studies of skeletal morphology, and he willed that his dead body was offered as a material for these studies. According to his will, the skeletal remains of both Dr. Takeo KANASEKI and his father, Mr. Kisaburo KANASEKI, have been kept in the Department of Anatomy, Faculty of Medicine, Kyushu University.
At first, I performed the morphological investigation and the intra-familial comparison on the skeletal measurements of the KANASEKIfamily. Then, to detect the factors influencing the shape of the human skeleton, I examined osteometric data of the KANASEKI-family and some other skeletal series using multivariate statistical analysis by the following procedures:
1) In order to estimate the family resemblances in skeletal morphology, Q-mode correlation coefficients and standardized Euclidean distances were calculated for the skeletal measurements of the relatives from 4 pedigrees and of 230 pairs of unrelated individuals from the recent Japanese.
2) Heritabilities in the skeletal measurements of 4 pedigrees were estimated according to FALCONER (1989) and SJφVOLD (1984).
3) The measurements from 6 populations (cf. Table 2.) belonging to some different social ranks were analyzed by canonical discriminant analysis to detect the factors affecting the shape of human skeleton.
The results obtained were as follows:
1) There was a marvelous similarity between skeletal morphology of the KANASEKI-family in neurocranium, humerus, femur and tibia.
2) Morphological similarities in the relatives were significantly strong even in the extremity bones.
3) High heritabilities were estimated at the epiphyseal part of the extremity bones.
4) Environmental factors affecting the shape of the human skeletons consisted of social rank and the period that the population belonged to. The former seemed to be related with mechanical stresses on the bone and the latter with living conditions such as nutrition and medical care.
5) The influence by mechanical stress was remarkably recognized in such high mobility areas, as facial cranium, forearm and leg.
6) The influence on bones by living condition was more remarkable in the lower extremity than in the upper one.