[Heritability of human skeletal morphology].
The shape of human skeleton is determined by both genetic and environmental factors. In this report, I discussed the relative contribution of these two components in the osteometric traits by investigating 6 skeletal series affiliated to different social ranks. They were composed of 4 pedigrees, the Kanaseki family, the Tokugawa family (Shogun), the Makino family (Daimyo) and the Kuse family (Karo), and two control samples of unrelated individuals from the Edo period and recent times. The three familial samples, except the Kanaseki family, were the Japanese aristocrats of the Edo period. To estimate the family resemblance in skeletal morphology, I calculated Q-mode correlation coefficients (Q) and standardized Euclidean distances (D) for skeletal measurements of the relatives from 4 pedigrees and control samples of recent Japanese. Comparing Q and D between related and unrelated pairs, strong resemblances were detected among the related one. Family resemblance tended to reveal remarkable similarities in neuro-cranium, humerus, femur and tibia. Then, to determine the genetic contribution to these family resemblances, I estimated heritabilities (h2) for each measurement according to Falconer and Sjøvold. High heritabilities were seen in skull measurements as mentioned by Sjøvold. However, high heritabilities were also demonstrated in the epiphyseal part of the extremity bones. Environmental factors affecting the shape of human skeleton were analyzed by using canonical discriminant analysis for the measurements of the 6 skeletal series. Two environmental factors, social rank and the period that populations belong to, were detected from these analyses. Social rank seemed to be related with mechanical stress on the bone and the period with living condition such as nutrition and medical care. The influence by mechanical stress was remarkably recognized in such high mobility areas as facial cranium, forearm and leg. On the other hand, the influence on bones by living condition was more remarkable in the lower extremity than in the upper one.
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Department of Anatomy, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan.
D000886:Anthropometry; D044466:Asian People; D001842:Bone and Bones / Q000033:anatomy & histology*; D004777:Environment; D005828:Genetics, Population; D006801:Humans; D007564:Japan; D010375:Pedigree; D012923:Social Class