“…Selection against high intelligence has been observed throughout most of the 20th century in Europe and the United States (Cattell, 1936(Cattell, , 1937Lynn & van Court 2004;Retherford & Sewell, 1988;van Court & Bean, 1985), where it was probably present since the beginning of the fertility transition in the 19th century (Notestein, 1936;Stevenson, 1920). We can estimate that without this selection effect the average intelligence in these countries today would be up to 5 points higher than it is-about as high as the average IQ in China today (Lynn & Vanhanen, 2006), where reproductive differentials still favored wealth, literacy and presumably intelligence in the early part of the 20th century (Lamson, 1935;Notestein, 1938).…”