Secular change in sitting height and lower limb height of children, youths, and young adults of Afro-black, European, and Japanese ancestry.

During a large part of the last 100 years many human populations in Asia, Australia, Europe, and North America have increased in standing height. The amount of increase has risen with age from infancy to mid-adolescence, and diminished with age from mid-adolescence to early adulthood. In the present paper standing height is broken into two components and-for American black, American white, and Japanese groups-each component is found to (1) show substantial secular increase, and (2) yield a trend of quantitative difference similar to that of standing height. Average sitting height of Japanese males increased during the 33 years between 1937 and 1970 by 2.5 cm at age 8 years, 4.1 cm at age 14 years, and 2.9 cm at age 16 years; corresponding values for lower limb height were 3.7 cm, 5.3 cm, and 3.9 cm. During the 80 years following 1881, American white females ages 9 years and 13 years living in the Midwest increased in average sitting height by 4.6 cm and 5.4 cm, and in average lower limb height by 4.9 cm and 5.2 cm. For both dimensions of each racial group, secular change is greater at mid-adolescence than in early adulthood.