Multiple regression analysis of anthropometric measurements influencing the cephalic index of male Japanese university students

I NTRO D U C TIO NHead form has been of major interest to human biologists and anthropologists since Anders Retzius (1796-1860), a Swedish professor of anatomy, developed the cephalic index (CI) as a method of describing head shape in 1842.(1) The CI, which is derived by dividing maximum head breadth (eu-eu) by maximum head length (g-op) and multiplying the result by 100, gives the ratio of head breadth to head length.It is widely used not only to categorise human populations, but also to describe an individual's appearance and estimate the age of fetuses for legal and obstetrical purposes.(2) CI is also used in the investigation of normal brain development in children.(3) A previous study by Asha et al reported that three variables -CI, index of head size and morphological upper facial index -could accurately classify patients with Down syndrome.(4) Head form presumably reflects an aspect of brain size, i.e. the longest head length defining the greatest anterior-posterior diameter of the brain case and the widest head breadth representing the greatest transverse diameter of the brain case.If the brain case is short but relatively broader, the head is considered brachycephalic (round-headed), and if the brain case is long but relatively narrower, the head is deemed to be dolichocephalic (long-headed).An increase in CI indicates a tendency toward round-headedness.In the last century, many researchers have used CI to describe the characteristics of head forms in different races all over the world.(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) In Japan, Suzuki reported the protohistoric Japanese population as long-headed and broad-faced with strong prognathism.(15) Subsequent researchers have also published studies on the CI of the Japanese.(16)(17)(18)(19)(20)(21)(22)(23) More recently, researchers, such as Hossain et al (23,24) and Kouchi, (25) have studied secular changes in CI over time, attributing the increase in CI in the Japanese to an increase in head breadth.(23)(24)(25) More recently, Hossain et al have reported that the best predictor dimensions for face form among adult female Japanese students were head length (g-op), head circumference (g-g), head breadth (eu-eu), minimum frontal breadth (ft-ft) and head height (v-po).(26) This suggests that factors that contribute to changes in the anthropometric measurements of a population can be expected to influence the size and shape of the head of individuals in that population.However, information on the association between changes in general physical form and head form is still lacking.The aim of the present study was to investigate the relationship between anthropometric characteristics and the CI of adult male Japanese students.