“…Considering that they survived the North Korean regime and life-threatening emigration, this mean age at menarche was likely to be biased downward. Pak et al (2011) argued that the biological standards of living (measured by height) did not improve at all for the birth years 1940-1989, thus, this mean age at menarche may not much differ from those for earlier birth years, after adjusting for the downward bias. Furthermore, immediately after the colonization of Korea in 1910, a mean age at menarche of 16 years and 6 months was observed for women in northwestern Korea (cited from Lee, 1930, p. 33); the area was in the middle income range in Korea at the time.…”