This kind of claim is very common, even among people who explicitly reject blank slatism. It is odd because there are such results around, and they have been around for a long time. Richard Lynn, as usual, deserves credit for going against the stream and arguing the evidence-based contrarian position while others make claims of no gaps citing nothing. A recent summary by
With regard to possible causes of the slight female decline in IQ illustrated in Table 5 above during their fertile early adulthood, see https://www.frontiersin.org/articles/10.3389/fnbeh.2021.658769/full -- and then https://sci-hub.ru/10.1016/0002-9378(72)90098-1. Seems possible that since the 1960s' introduction of the pill an appreciable part of the female population has been chemically hitting itself in the head in its efforts to avoid pregancy. This mechanism would especially impact European and European-derived populations with their relatively high proportion of COMT(Met,Met) carriers. Oops.
With regard to possible causes of the slight female decline in IQ illustrated in Table 5 above during their fertile early adulthood, see https://www.frontiersin.org/articles/10.3389/fnbeh.2021.658769/full -- and then https://sci-hub.ru/10.1016/0002-9378(72)90098-1. Seems possible that since the 1960s' introduction of the pill an appreciable part of the female population has been chemically hitting itself in the head in its efforts to avoid pregancy. This mechanism would especially impact European and European-derived populations with their relatively high proportion of COMT(Met,Met) carriers. Oops.
Reportedly, social status correlates with a skew in the sex ratio of offspring. If true, that would explain (some?) of the gap.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0004195
>human mothers in the highest economic bracket do give birth to more sons, suggesting similar sex ratio manipulation as seen in other mammals.