Somatic comparisons of South Korean children and youths born and reared in a rural area with the descendants of rural to urban migrants.

During April-May 2000 somatic data were collected on 236 males and 191 females ages 6, 9, 13, and 15 years residing in rural areas around the communities of Ankye, Euisung, and Kunwi in Kyungsang Puk Do province, South Korea, and 237 males and 219 female of the same ages born and reared at Taegu in families of "rural to urban migrants." Comparisons were made between urban and rural groups for measures of body size and form, skinfold thickness, the body mass index (BMI), and estimated arm muscle area (ARM). Age at menarche was obtained from school records for the 13- and 15-year-olds. The data were analyzed in separate 2 (urban-rural) x 4 (age) analyses of variance with an alpha level of P < 0.01. Age differences were significant for all dimensions. There was a significant main effect for urban-rural differences in arm girth, upper limb index, and ARM. Rural males were larger in these variables. Among females, only arm girth was significantly different. Age at menarche was significantly earlier in the urban sample (12.6 years) than in the rural sample (13.0 years). Compared with both recent and earlier data for South Korea, present-day 6-, 9-, 13-, and 15-year-old males and females are taller and heavier at every age, indicating secular gains.